Image processing device, recording device, image processing method and storage medium

Abstract

The present invention relates to an image processing device, a recording device, an image processing method and a storage medium for forming an image of a shape other than a two-dimensional plane. The image processing device is characterized in that it comprises: a distribution unit that distributes an error caused by quantization of a grayscale value corresponding to a pixel to a first pixel located in a first direction of the pixel at a first distribution rate, distributes it to a second pixel located in a second direction of the pixel at a second distribution rate, and distributes it to a third pixel located in a third direction of the pixel at a third distribution rate, wherein the second direction is a direction intersecting the first direction, and the third direction is a direction different from the extension direction of a plane defined by the first direction and the second direction.

Description

Technical Field

[0001] The present invention relates to an image processing device, a recording device, an image processing method and a program. Background Art

[0002] Conventionally, there is known a technique for forming an image on a two-dimensional plane by performing halftone processing using an error diffusion method as described in Patent Document 1.

[0003] However, the conventional technology has a problem that it is impossible to form an image in a shape other than a two-dimensional plane.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2020-065100 Summary of the invention

[0005] In order to solve the above problems, an image processing device involved in one embodiment of the present invention is characterized in that it comprises: an acquisition unit, which acquires image data representing the grayscale value of an image that should be displayed by each of a plurality of pixels in the three-dimensional space when the image is displayed in the three-dimensional space; a generation unit, which generates display data by quantizing the grayscale value represented by the image data, and the generation unit comprises: a selection unit, which selects a pixel from the plurality of pixels; and an allocation unit, which allocates an error caused by quantization of the grayscale value corresponding to the one pixel to a first pixel located in a first direction of the one pixel at a first allocation rate, to a second pixel located in a second direction of the one pixel at a second allocation rate, and to a third pixel located in a third direction of the one pixel at a third allocation rate, wherein the second direction is a direction intersecting the first direction, and the third direction is a direction different from the extension direction of the plane defined by the first direction and the second direction.

[0006] In addition, a recording device involved in another embodiment of the present invention is characterized in that it forms an image for an object object with a three-dimensional shape, and comprises: a head unit that ejects liquid; a control unit that controls the ejection of liquid from the head unit to form the image for the object by using a plurality of points whose configuration is determined by using an error diffusion method and formed by the liquid ejected from the head unit, the control unit controls the ejection of liquid from the head unit so that when the object object has a first surface, the distribution of the plurality of points on the first surface has a frequency characteristic in which high-frequency components higher than a predetermined frequency are more than low-frequency components lower than the predetermined frequency in a spatial frequency domain, and when the object object has a second surface that is not parallel to the first surface, the distribution of the plurality of points on the second surface has a frequency characteristic in which high-frequency components higher than a predetermined frequency are more than low-frequency components lower than the predetermined frequency in a spatial frequency domain.

[0007] In addition, an image processing method involved in one embodiment of the present invention is characterized in that it comprises: an acquisition step of acquiring image data representing the grayscale value of an image that should be displayed by each of a plurality of pixels in the three-dimensional space when the image is displayed in the three-dimensional space; a generation step of generating display data by quantizing the grayscale value represented by the image data, the generation step comprising: a selection step of selecting a pixel from the plurality of pixels; and an allocation step of allocating an error caused by quantization of the grayscale value corresponding to the pixel to a first pixel located in a first direction of the pixel at a first allocation rate, to a second pixel located in a second direction of the pixel at a second allocation rate, and to a third pixel located in a third direction of the pixel at a third allocation rate, the second direction being a direction intersecting the first direction, and the third direction being a direction different from the extension direction of the plane defined by the first direction and the second direction.

[0008] In addition, a program involved in one embodiment of the present invention is characterized in that it causes a computer to function as the following component, wherein the component includes: an acquisition unit, which acquires image data representing the grayscale value of an image that should be displayed by each of a plurality of pixels in the three-dimensional space when the image is displayed in the three-dimensional space; a generation unit, which generates display data by quantizing the grayscale value represented by the image data, and the generation unit functions as a selection unit and an allocation unit, the selection unit selects a pixel from the plurality of pixels, and the allocation unit allocates an error caused by quantization of the grayscale value corresponding to the one pixel to a first pixel located in a first direction of the one pixel at a first allocation rate, to a second pixel located in a second direction of the one pixel at a second allocation rate, and to a third pixel located in a third direction of the one pixel at a third allocation rate, wherein the second direction is a direction intersecting the first direction, and the third direction is a direction different from the extension direction of the plane defined by the first direction and the second direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is an explanatory diagram showing an example of a recording system Sys according to an embodiment of the present invention.

[0010] Figure 2 A functional block diagram showing an example of the structure of the terminal device 1.

[0011] Figure 3 It is a functional block diagram showing an example of the structure of the recording device 5.

[0012] Figure 4 It is an explanatory diagram showing an example of the image forming space SP.

[0013] Figure 5 1 is an explanatory diagram showing an example of the image data GD.

[0014] Figure 6 This is a flowchart showing an example of display data generation processing.

[0015] Figure 7 is an explanatory diagram showing an example of the error diffusion data GK.

[0016] Figure 8 It is an explanatory diagram showing an example of error diffusion data GK-Z1 according to the reference example.

[0017] Fig. 9 This is an explanatory diagram showing an example of display data generation processing according to the reference example.

[0018] Fig.10This is an explanatory diagram showing an example of display data generation processing according to the reference example.

[0019] Fig.11 It is an explanatory diagram showing an example of display data Img involved in the reference example.

[0020] Fig.12 It is an explanatory diagram showing an example of display data Img involved in the reference example.

[0021] Fig.13 It is an explanatory diagram showing an example of error diffusion data GK-Z2 involved in the reference example.

[0022] Fig.14 It is an explanatory diagram showing an example of error diffusion data GK-Z3 involved in the reference example.

[0023] Fig.15 This is an explanatory diagram showing an example of display data generation processing.

[0024] Fig.16 This is an explanatory diagram showing an example of display data generation processing.

[0025] Fig.17 It is an explanatory diagram showing an example of display data Img.

[0026] Fig.18 It is an explanatory diagram showing an example of display data Img.

[0027] Fig.19 It is an explanatory diagram showing an example of the curve FB.

[0028] Fig. 20 1 is an explanatory diagram showing an example of error diffusion data GK-A according to Modification 1.

[0029] Fig.21 1 is an explanatory diagram showing an example of error diffusion data GK-B according to Modification 1.

[0030] Fig. 22 1 is an explanatory diagram showing an example of error diffusion data GK-C according to Modification 1.

[0031] Fig.23 1 is an explanatory diagram showing an example of error diffusion data GK-D according to Modification 1.

[0032] Fig.24 1 is an explanatory diagram showing an example of error diffusion data GK-E according to Modification 1.

[0033] Fig.25This is a flowchart showing an example of display data generation processing according to Modification 2.

[0034] Fig.26 This is a flowchart showing an example of display data generation processing according to Modification 3.

[0035] Fig. 27 This is a flowchart showing an example of display data generation processing according to Modification 3. DETAILED DESCRIPTION

[0036] Hereinafter, the method for implementing the present invention will be described with reference to the accompanying drawings. However, in each of the accompanying drawings, the size and scale of each part are appropriately different from the actual situation. In addition, although the embodiments described below are preferred specific examples of the present invention and various technically preferred limitations are added, in the following description, as long as there is no record of particularly limiting the present invention, the scope of the present invention is not limited to these methods.

[0037] <<A. Implementation Method>>

[0038] The recording system Sys according to this embodiment will be described.

[0039] In the present embodiment, the recording system Sys is a system for forming an image G on the surface SF of the target object Obj having a three-dimensional shape. In addition, the recording system Sys can also form an image G for the target object Obj having a two-dimensional shape.

[0040] <<1. Overview of the Recording System Sys>>

[0041] In the following, first, in reference to Figures 1 to 3 At the same time, an example of an outline of the structure of the recording system Sys involved in this embodiment is described.

[0042] Figure 1 It is an explanatory diagram showing an example of the recording system Sys.

[0043] like Figure 1 As illustrated, the recording system Sys includes a terminal device 1 and a recording device 5 .

[0044] Here, the terminal device 1 generates display data Img representing the image G formed by the recording system Sys on the surface SF of the target object Obj.

[0045] Furthermore, the recording device 5 forms an image G represented by the display data Img for the surface SF of the target object Obj based on the display data Img generated by the terminal device 1 .

[0046] In addition, if Figure 1 As illustrated, the terminal device 1 sets a three-dimensional coordinate system having an X-axis, a Y-axis, and a Z-axis in an image forming space SP as a three-dimensional space in which the object Obj exists. In the following, a direction along the X-axis is referred to as the +X direction, a direction opposite to the +X direction is referred to as the -X direction, a direction along the Y-axis is referred to as the +Y direction, a direction opposite to the +Y direction is referred to as the -Y direction, a direction along the Z-axis is referred to as the +Z direction, and a direction opposite to the +Z direction is referred to as the -Z direction. In addition, in the following, the +X direction and the -X direction are sometimes collectively referred to as the X-axis direction, the +Y direction and the -Y direction are collectively referred to as the Y-axis direction, and the +Z direction and the -Z direction are collectively referred to as the Z-axis direction. In addition, although the present embodiment assumes that the terminal device 1 sets the X-axis, the Y-axis, and the Z-axis to be orthogonal to each other, the present invention is not limited to this method, as long as the X-axis, the Y-axis, and the Z-axis are defined to intersect with each other.

[0047] Figure 2 A functional block diagram showing an example of the structure of the terminal device 1.

[0048] like Figure 2 As illustrated, the terminal device 1 includes a terminal control unit 2 and a storage unit 3 .

[0049] The storage unit 3 stores the image data GD, the error diffusion data GK, and the control program Pgt of the terminal device 1 .

[0050] Here, the image data GD, for example, represents an image Gf that a user of the recording system Sys wants to form on the surface SF of the target object Obj using the recording system Sys. Specifically, the image data GD represents the grayscale value of the image Gf corresponding to each pixel of the plurality of pixels Px constituting the image forming space SP. In addition, although the details will be described below, the recording system Sys is sometimes unable to express the grayscale value of the image Gf represented by the image data GD. Therefore, the recording system Sys forms an image G that expresses the image Gf with a grayscale value that the recording system Sys can express. Specifically, the recording system Sys uses the error diffusion data GK stored in the storage unit 3 and generates display data Img based on the image data GD, and forms the image G represented by the generated display data Img on the surface SF of the target object Obj.

[0051] In addition, the error diffusion data GK will be described later.

[0052] like Figure 2As shown in the example, the terminal control unit 2 is configured to include one or more CPUs and controls various parts of the terminal device 1. Here, CPU is an abbreviation of Central Processing Unit. The one or more CPUs provided in the terminal control unit 2 can function as the image data acquisition unit 21 and the display data generation unit 22 by executing the control program Pgt stored in the storage unit 3 and working according to the control program Pgt.

[0053] The image data acquisition unit 21 acquires the image data GD stored in the storage unit 3. In addition, although the image data GD is stored in the storage unit 3 as an example in the present embodiment, the present invention is not limited to this method. The image data GD may be stored in an external device outside the terminal device 1, for example. In this case, the image data acquisition unit 21 only needs to acquire the image data GD from the external device.

[0054] Furthermore, the display data generating unit 22 generates the display data Img by executing a quantization process which is a process of quantizing the grayscale value of the pixel Px represented by the image data GD. Specifically, in the present embodiment, as the quantization process, the display data generating unit 22 implements a so-called error diffusion process which sequentially changes the grayscale value for each pixel Px while reflecting an error when the grayscale value of the image Gf corresponding to one pixel Px is changed to the grayscale value of the image Gf corresponding to other pixels Px.

[0055] In the present embodiment, the display data generation unit 22 includes a pixel selection unit 221, an operation processing unit 222, and an error allocation unit 223. The pixel selection unit 221 selects a pixel Px that is a target of error diffusion processing, that is, a target pixel PxT. In addition, the operation processing unit 222 determines the grayscale value of the image G corresponding to the target pixel PxT by applying error diffusion processing to the grayscale value of the image Gf corresponding to the target pixel PxT. In addition, the error allocation unit 223 allocates the error E between the grayscale value of the image Gf corresponding to the target pixel PxT and the grayscale value of the image G corresponding to the target pixel PxT to the grayscale value of the image Gf corresponding to the surrounding pixels PxS located around the target pixel PxT by using the error diffusion data GK.

[0056] Figure 3 It is a functional block diagram showing an example of the structure of the recording device 5.

[0057] like Figure 3 As illustrated, the recording device 5 includes a recording control unit 6 , a head unit 7 , an ink supply unit 8 , and a robot arm 9 .

[0058] The recording control unit 6 includes a processing circuit such as a CPU or FPGA and a storage circuit such as a semiconductor memory, and controls each element of the recording device 5. Here, FPGA is an abbreviation of Field Programmable Gate Array. The processing circuit provided in the recording control unit 6 can function as a head control unit 61 and an arm control unit 62.

[0059] The head control unit 61 generates a drive control signal SI for controlling the drive of the head unit 7 based on the display data Img. The head control unit 61 also generates a drive signal Com for driving the head unit 7 and a control signal Ctr-L for controlling the ink supply unit 8.

[0060] Furthermore, the arm control unit 62 generates a control signal Ctr-R for controlling the position and posture of the robot arm 9 in the image forming space SP based on the display data Img.

[0061] The head unit 7 includes a driving signal supply section 71 and a recording head 72 .

[0062] The recording head 72 includes a plurality of ejection units D. Each ejection unit D is driven by a drive signal Com to eject ink filled in the ejection unit D, thereby forming dots on the surface SF of the target object Obj.

[0063] Furthermore, the drive signal supply unit 71 switches whether to supply the drive signal Com to each of the plurality of discharge units D based on the drive control signal SI.

[0064] In addition, in the present embodiment, a case where the head unit 7 is attached to the tip of the robot arm 9 is assumed as an example.

[0065] The ink supply unit 8 supplies the ink stored in the ink supply unit 8 to the head unit 7 based on the control signal Ctr-L.

[0066] The robot arm 9 changes the position and posture of the tip of the robot arm 9 in the image forming space SP based on the control signal Ctr-R. As a result, the robot arm 9 changes the position and posture of the head unit 7 in the image forming space SP so that the head unit 7 mounted at the tip of the robot arm 9 is in a position and posture that is preferred for forming an image G on the surface SF of the object Obj.

[0067] As described above, when the display data Img is supplied, the recording control unit 6 controls the ejection of ink from the plurality of ejection portions D provided on the head unit 7 by means of the drive control signal SI generated based on the display data Img. In addition, the recording control unit 6 controls the position and posture in the image forming space SP of the head unit 7 mounted at the top end of the robot 9 by means of the control signal Ctr-R generated based on the display data Img. Therefore, the recording device 5 can form an image G corresponding to the display data Img for the surface SF of the object Obj arranged in the image forming space SP. Hereinafter, the process in which the recording device 5 forms the image G corresponding to the display data Img for the surface SF of the object Obj is sometimes referred to as a printing process.

[0068] 2. Image formation space and image data

[0069] In the following, in reference to Figure 4 as well as Figure 5 At the same time, the image forming space SP and the image data GD are described.

[0070] Figure 4 1 is an explanatory diagram showing an example of a plurality of pixels Px arranged in the image forming space SP.

[0071] like Figure 4 As illustrated, in the image forming space SP involved in the present embodiment, a total of Mx*My*Mz pixels Px are arranged in such a manner that Mx pixels Px extend in the X-axis direction, My pixels Px extend in the Y-axis direction, and Mz pixels Px extend in the Z-axis direction. Here, the value Mx, the value My, and the value Mz are natural numbers greater than 2. In addition, the value Mx, the value My, and the value Mz are preferably natural numbers greater than 128. In the present embodiment, as an example, a case where the value Mx, the value My, and the value Mz are natural numbers greater than 256 is assumed. In addition, hereinafter, a natural number M that becomes "M=Mx*My*Mz" is defined. That is, in the present embodiment, M pixels Px are arranged in the image forming space SP.

[0072] Furthermore, in the following, a variable mx of a natural number satisfying 1≤mx≤Mx is imported, a variable my of a natural number satisfying 1≤my≤My is imported, and a variable mz of a natural number satisfying 1≤mz≤Mz is imported. Figure 4As illustrated, among the M pixels Px existing in the image forming space SP, the pixel Px located at the mxth position from the -X side to the +X side in the X-axis direction, the myth position from the -Y side to the +Y side in the Y-axis direction, and the mzth position from the -Z side to the +Z side in the Z-axis direction is sometimes referred to as a pixel Px (mx, my, mz). In addition, hereinafter, the position of the pixel Px (mx, my, mz) in the image forming space SP in the X-axis direction is referred to as "X[mx]", the position of the pixel Px (mx, my, mz) in the image forming space SP in the Y-axis direction is referred to as "Y[my]", and the position of the pixel Px (mx, my, mz) in the image forming space SP in the Z-axis direction is referred to as "Z[mz]". That is, the position of the pixel Px (mx, my, mz) in the image forming space SP is expressed as (X, Y, Z) = (X[mx], Y[my], Z[mz]).

[0073] In addition, hereinafter, a plurality of pixels Px located at Y=Y[my] and at Z=Z[mz] are referred to as pixel columns PxL[my][mz]. The pixel column PxL[my][mz] is composed of Mx pixels Px extending in the X-axis direction. The M pixels Px present in the image forming space SP include (My*Mz) pixel columns PxL[my][mz].

[0074] In addition, hereinafter, a plurality of pixels Px located at Z=Z[mz] are referred to as pixel planes PxP[mz]. The pixel plane PxP[mz] is composed of (Mx*My) pixels Px existing on a plane parallel to the XY plane. The M pixels Px existing in the image forming space SP include Mz pixel planes PxP[mz].

[0075] Figure 5 is an explanatory diagram for explaining an example of image data GD. Figure 5 In the above description, it is assumed as an example that the surface SF of the target object Obj includes a plane SF1, a plane SF2, and a plane SF3.

[0076] As described above, the image data GD is data representing the image Gf. Specifically, the image data GD represents the grayscale value that should be displayed by each of the M pixels Px existing in the image forming space SP in order to display the image Gf in the image forming space SP. Figure 5 As illustrated, the grayscale value of the image Gf in the pixel Px (mx, my, mz) represented by the image data GD is referred to as the grayscale value Gg (mx, my, mz). In addition, hereinafter, the grayscale value of the image Gf in the pixel Px represented by the image data GD is sometimes referred to as simply the grayscale value Gg.

[0077] In the present embodiment, it is assumed that the grayscale value Gg(mx, my, mz) is a natural number between the minimum grayscale value Gg-min and the maximum grayscale value Gg-max. Specifically, in the present embodiment, for example, it is assumed that the grayscale value Gg-min is "0" and the grayscale value Gg-max is "255". Moreover, in the present embodiment, it is assumed that the grayscale value Gg(mx, my, mz) is any one of the 256 values ​​from "0" to "255".

[0078] In addition, in the present embodiment, for a pixel Px(mx, my, mz) on the surface SF where the target object Obj does not exist in the image forming space SP, the grayscale value Gg(mx, my, mz) is set to the grayscale value Gg-min. In addition, in the present embodiment, when the grayscale value Gg(mx, my, mz) is the grayscale value Gg-min, the pixel Px(mx, my, mz) is a pixel Px that does not display anything.

[0079] In addition, as described above, the terminal control unit 2 generates display data Img based on the image data GD. The display data Img represents the grayscale value that should be displayed by each of the M pixels Px existing in the image forming space SP in order to form the image G on the surface SF of the target object Obj existing in the image forming space SP.

[0080] Hereinafter, the grayscale value of the image G in the pixel Px (mx, my, mz) represented by the display data Img is referred to as the grayscale value GI (mx, my, mz). In the present embodiment, it is assumed that the grayscale value GI (mx, my, mz) represents the value of either the maximum grayscale value GI-1 or the minimum grayscale value GI-0. In addition, in the present embodiment, as an example, it is assumed that the maximum grayscale value GI-1 is the same value "255" as the grayscale value Gg-max, and the minimum grayscale value GI-0 is the same value "0" as the grayscale value Gg-min.

[0081] Furthermore, in the present embodiment, at the pixel Px (mx, my, mz) where the grayscale value GI (mx, my, mz) is the highest grayscale value GI-1, a dot is formed by the ink ejected from the recording device 5. On the other hand, in the present embodiment, no dot is formed at the pixel Px (mx, my, mz) where the grayscale value GI (mx, my, mz) is the lowest grayscale value GI-0. Hereinafter, the pixel Px where the highest grayscale value Gg-1 is displayed and a dot is formed is referred to as a dot-formed pixel Px-1. Furthermore, the pixel Px where the lowest grayscale value Gg-0 is displayed and a dot is not formed is referred to as a dot-non-formed pixel Px-0.

[0082] 3. Record the work of the system

[0083] In the following, in reference to Figure 6 as well as Figure 7 At the same time, an example of the operation of the recording system Sys involved in this embodiment is described. In addition, in this embodiment, Figure 6 The processing of steps S10 to S23 in is equivalent to the error diffusion processing (quantization processing) for the M pixels Px.

[0084] Figure 6 1 is a flowchart showing an example of the operation of the recording system Sys when the recording system Sys performs display data generation processing. Here, the display data generation processing refers to the processing of generating display data Img based on the image data GD. In other words, the display data generation processing refers to the error diffusion processing for M pixels Px.

[0085] like Figure 6 As illustrated, when the display data generation process starts, the pixel selection unit 221 sets the variable mx to “1”, sets the variable my to “1”, and sets the variable mz to “1” ( S10 ).

[0086] Next, the pixel selection unit 221 selects a pixel Px(mx, my, mz) as a target pixel PxT ( S11 ).

[0087] Thereafter, the calculation processing unit 222 determines whether the grayscale value of the image Gf in the target pixel PxT represented by the image data GD, that is, the grayscale value Gg(mx, my, mz) is greater than the threshold value Th(mx, my, mz) (S12). Here, the threshold value Th(mx, my, mz) refers to a value that satisfies the following formula (1).

[0088] (1-γ1)*Gg-min+γ1*Gg-max

[0089] ≤Th(mx,my,mz)

[0090] ≤(1-γ2)*Gg-min+γ2*Gg-max...Equation (1)

[0091] In the present embodiment, the value γ1 is, for example, a real number satisfying "0.3≤γ1≤0.5", and the value γ2 is, for example, a real number satisfying "0.5≤γ2≤0.7". Furthermore, it is preferred that the threshold Th(mx, my, mz) is the same value in all the M pixels Px. Therefore, in the present embodiment, it is assumed that the threshold Th(mx, my, mz) is "128" in all the M pixels Px.

[0092] Next, when the result of the determination in step S12 is affirmative, the calculation processing unit 222 sets the grayscale value GI (mx, my, mz) corresponding to the pixel Px (mx, my, mz) as the target pixel PxT to the maximum grayscale value GI-1 (S13).

[0093] Then, the error allocator 223 calculates the error E corresponding to the pixel Px(mx,my,mz) based on the grayscale value Gg(mx,my,mz) and the grayscale value GI(mx,my,mz) set in step S13 (S14). In the present embodiment, as an example, the error allocator 223 calculates in step S14 a value obtained by subtracting the grayscale value Gg(mx,my,mz) from the grayscale value GI(mx,my,mz) as the error E corresponding to the pixel Px(mx,my,mz). More specifically, in step S14, the error allocator 223 calculates a value obtained by adding "1" to the highest grayscale value GI-1 and further subtracting the grayscale value Gg(mx,my,mz) as the error E corresponding to the pixel Px(mx,my,mz). In addition, the error allocator 223 may also calculate, for example, in step S14, a value obtained by subtracting the grayscale value Gg(mx, my, mz) from the maximum grayscale value GI-1 as the error E corresponding to the pixel Px(mx, my, mz). Hereinafter, the error E corresponding to the pixel Px(mx, my, mz) is sometimes referred to as the error E(mx, my, mz).

[0094] In addition, although in the present embodiment, the error allocation unit 223 calculates the error E(mx, my, mz) as a value obtained by subtracting the grayscale value Gg(mx, my, mz) from the grayscale value GI(mx, my, mz) in step S14, this method is an example and the present invention is not limited to this method. For example, the error allocation unit 223 may also calculate the error E(mx, my, mz) as a value obtained by subtracting the grayscale value Gg(mx, my, mz) from a constant such as the grayscale value Gg-max. In this case, the highest grayscale value GI-1 may be set to "1" and the lowest grayscale value GI-0 may be set to "0". In the present embodiment, the error E(mx, my, mz) calculated in step S14 satisfies "E(mx, my, mz) ≥ 0".

[0095] On the other hand, when the result of the judgment in step S12 is negative, the operation processing unit 222 sets the grayscale value GI (mx, my, mz) corresponding to the pixel Px (mx, my, mz) as the object pixel PxT to the minimum grayscale value GI-0 (S15).

[0096] Then, the error allocator 223 calculates the error E(mx, my, mz) based on the grayscale value Gg(mx, my, mz) and the grayscale value GI(mx, my, mz) set in step S15 (S16). Specifically, the error allocator 223 calculates the value obtained by subtracting the grayscale value Gg(mx, my, mz) from the grayscale value GI(mx, my, mz) in step S16 as the error E(mx, my, mz). More specifically, the error allocator 223 calculates the value obtained by subtracting the grayscale value Gg(mx, my, mz) from the minimum grayscale value GI-0 in step S16 as the error E(mx, my, mz).

[0097] In addition, although the error allocator 223 calculates the error E(mx, my, mz) as a value obtained by subtracting the grayscale value Gg(mx, my, mz) from the grayscale value GI(mx, my, mz) in step S16 in the present embodiment, this method is an example and the present invention is not limited to this method. For example, the error allocator 223 may calculate the error E(mx, my, mz) as a value obtained by subtracting the grayscale value Gg(mx, my, mz) from a constant such as the grayscale value Gg-min. In this case, the highest grayscale value GI-1 may be set to "1" and the lowest grayscale value GI-0 may be set to "0".

[0098] In the present embodiment, the error E(mx, my, mz) calculated in step S16 satisfies “E(mx, my, mz)≤0”.

[0099] In addition, in this embodiment, if Figure 6 As illustrated as step S100 in FIG. 2 , the processing of steps S12 , S13 , and S15 executed by the arithmetic processing unit 222 corresponds to the error diffusion processing for one pixel Px (the quantization processing for one pixel Px).

[0100] Thereafter, the error allocator 223 performs an error allocation process of allocating the error E(mx, my, mz) to one or more grayscale values ​​Gg corresponding to one or more surrounding pixels PxS located around the target pixel PxT using the error diffusion data GK (S17). In addition, hereinafter, when the target pixel PxT is a pixel Px(mx, my, mz), the surrounding pixel PxS is sometimes expressed as a pixel Px(mx+dx, my+dy, mz+dz). Here, the value dx, the value dy, and the value dz are integers.

[0101] Specifically, in the error allocation processing of step S17, the error allocation unit 223 changes the grayscale value Gg(mx+dx, my+dy, mz+dz) corresponding to the pixel Px(mx+dx, my+dy, mz+dz) based on the following equations (2) and (3) when there is a pixel Px(mx+dx, my+dy, mz+dz) as a surrounding pixel PxS.

[0102] Gg(mx+dx,my+dy,mz+dz)

[0103] =Gg(mx+dx,my+dy,mz+dz)

[0104] -EB(dx, dy, dz)……Formula (2)

[0105] EB(dx,dy,dz)

[0106] ={E(mx, my, mz)*B(dx, dy, dz)}... Formula (3)

[0107] That is, in the error allocation process of step S17, the error allocation unit 223 changes the grayscale value Gg(mx+dx,my+dy,mz+dz) represented by the image data GD by subtracting the allocation value EB(dx,dy,dz) obtained by multiplying the error E(mx,my,mz) by the allocation ratio B(dx,dy,dz) from the grayscale value Gg(mx+dx,my+dy,mz+dz). In addition, in the present embodiment, as an example, when the right side of the equation (3) contains a value after the decimal point, the right side of the equation (3) is subjected to rounding, rounding up, or truncation so that the allocation value EB(dx,dy,dz) becomes an integer value.

[0108] Here, the distribution ratio B(dx, dy, dz) is a real number satisfying “0<B(dx, dy, dz)<1”. In addition, in the present embodiment, one or more surrounding pixels PxS corresponding to the target pixel PxT and the distribution ratio B corresponding to each surrounding pixel PxS are determined by the error diffusion data GK.

[0109] Figure 7 It is an explanatory diagram for explaining the error diffusion data GK according to the present embodiment.

[0110] like Figure 7As shown in FIG. 1 , the error diffusion data GK is data for determining the surrounding pixels PxS and the distribution rate B corresponding to the surrounding pixels PxS. Specifically, when the pixel Px(mx, my, mz) is the target pixel PxT, the error diffusion data GK is data for associating the value dx, the value dy, and the value dz for determining the surrounding pixels PxS, that is, the pixel Px(mx+dx, my+dy, mz+dz), with the distribution rate B(dx, dy, dz) corresponding to the pixel Px(mx+dx, my+dy, mz+dz).

[0111] In addition, in this embodiment, as an example, it is envisioned that when the object pixel PxT is the pixel Px(mx, my, mz), the pixel Px(mx+1, my, mz), the pixel Px(mx, my+1, mz) and the pixel Px(mx, my, mz+1) are equivalent to the surrounding pixels PxS.

[0112] In addition, in this embodiment, it is envisioned that the following relationships represented by equations (4) to (6) hold true between the distribution rate B(1, 0, 0) corresponding to the pixel Px(mx+1, my, mz), the distribution rate B(0, 1, 0) corresponding to the pixel Px(mx, my+1, mz), and the distribution rate B(0, 0, 1) corresponding to the pixel Px(mx, my, mz+1).

[0113] B(1,0,0)>B(0,1,0)……Formula (4)

[0114] B(0,1,0)>B(0,0,1)……Formula (5)

[0115] B(1,0,0)+B(0,1,0)+B(0,0,1)=1

[0116] ……Formula (6)

[0117] That is, in this embodiment, it is assumed that the allocation rate B(1,0,0) is larger than the allocation rate B(0,1,0), and the allocation rate B(0,1,0) is larger than the allocation rate B(0,0,1). In addition, in this embodiment, it is assumed that the sum of the allocation rates B(1,0,0), B(0,1,0), and B(0,0,1) is "1".

[0118] More specifically, in the present embodiment, as an example, a case where the distribution ratio B(1,0,0) is "8 / 16", the distribution ratio B(0,1,0) is "5 / 16", and the distribution ratio B(0,0,1) is "3 / 16" is assumed. That is, in the present embodiment, in the error distribution processing of step S17, the error distribution unit 223 updates the grayscale value Gg(mx+1,my,mz) by subtracting the distribution value EB(1,0,0) obtained by multiplying the error E(mx,my,mz) by "8 / 16" from the grayscale value Gg(mx+1,my,mz), and by subtracting the distribution value EB(1,0,0) obtained by multiplying the error E(mx,my,mz) by "8 / 16" from the grayscale value Gg(mx+1,my,mz). The grayscale value Gg(mx, my+1, mz) is updated by multiplying the error E(mx, my, mz) by "5 / 16", that is, the assigned value EB(0, 1, 0), and the grayscale value Gg(mx, my, mz+1) is updated by subtracting the value obtained by multiplying the error E(mx, my, mz) by "3 / 16", that is, the assigned value EB(0, 0, 1) from the grayscale value Gg(mx, my, mz+1).

[0119] Back to Figure 6 Provide explanation.

[0120] like Figure 6 As shown, the pixel selection unit 221 determines whether the value mx corresponding to the pixel Px(mx, my, mz) satisfies "mx=Mx" (S18). In other words, in step S18, the pixel selection unit 221 determines whether the pixel Px(mx+1, my, mz) does not exist among the M pixels Px constituting the image forming space SP.

[0121] Then, when the result of the determination in step S18 is negative, that is, when the value mx satisfies “mx<Mx”, the pixel selection unit 221 adds “1” to the value mx ( S19 ), and proceeds with the process to step S11 .

[0122] On the other hand, when the result of the judgment in step S18 is affirmative, that is, when the value mx satisfies "mx=Mx" and the pixel Px(mx+1, my, mz) does not exist among the M pixels Px constituting the image forming space SP, the pixel selection unit 221 judges whether the value my corresponding to the pixel Px(mx, my, mz) satisfies "my=My" (S20). In other words, in step S20, the pixel selection unit 221 judges whether the pixel Px(mx, my+1, mz) does not exist among the M pixels Px constituting the image forming space SP.

[0123] Then, when the result of the judgment in step S20 is negative, that is, when the value my satisfies "my<My", the pixel selection unit 221 sets the value mx to "1" and adds "1" to the value my (S21), and advances the processing to step S11.

[0124] On the other hand, when the result of the judgment in step S20 is affirmative, that is, when the value my satisfies "my=My" and the pixel Px(mx, my+1, mz) does not exist among the M pixels Px constituting the image forming space SP, the pixel selection unit 221 judges whether the value mz corresponding to the pixel Px(mx, my, mz) satisfies "mz=Mz" (S22). In other words, in step S22, the pixel selection unit 221 judges whether the pixel Px(mx, my, mz+1) does not exist among the M pixels Px constituting the image forming space SP.

[0125] Then, when the result of the judgment in step S22 is negative, that is, when the value mz satisfies "mz<Mz", the pixel selection unit 221 sets the value mx and the value my to "1", adds "1" to the value mz (S23), and enters the processing into step S11.

[0126] On the other hand, if the result of the determination in step S22 is positive, that is, if the value mz satisfies "mz=Mz" and there is no pixel Px(mx, my, mz+1) among the M pixels Px constituting the image forming space SP, the pixel selection unit 221 selects Figure 6 The display data generation process shown ends.

[0127] 4. Display Data Generation Processing in Reference Example

[0128] In the following, in order to make the effect of this embodiment clear, Figures 8 to 12 At the same time, the display data generation processing performed in the recording system involved in the reference example is explained.

[0129] The recording system according to the reference example is configured in the same manner as the recording system Sys according to the embodiment, except that error diffusion data GK-Z1 is stored instead of the error diffusion data GK.

[0130] Figure 8 It is an explanatory diagram for explaining the error diffusion data GK-Z1.

[0131] like Figure 8As shown, the error diffusion data GK-Z1 is data for designating the pixels Px(mx+1,my,mz) and the pixels Px(mx,my+1,mz) as the surrounding pixels PxS when the pixel Px(mx,my,mz) is the target pixel PxT. That is, the error diffusion data GK-Z1 is different from the error diffusion data GK involved in the embodiment in that the pixel Px(mx,my,mz+1) is not designated as the surrounding pixel PxS when the pixel Px(mx,my,mz) is the target pixel PxT.

[0132] In addition, the error diffusion data GK-Z1 is data that determines the distribution rate B(1,0,0) and the distribution rate B(0,1,0) so that the distribution rate B(1,0,0) corresponding to the pixel Px(mx+1,my,mz) is larger than the distribution rate B(0,1,0) corresponding to the pixel Px(mx,my+1,mz). More specifically, in the reference example, as an example, it is assumed that the error diffusion data GK-Z1 determines the distribution rate B(1,0,0) as "10 / 16" and the distribution rate B(0,1,0) as "6 / 16". That is, in the reference example, in the error allocation process, the error allocation unit 223 updates the grayscale value Gg(mx+1,my,mz) by subtracting the value obtained by multiplying the error E(mx,my,mz) by "10 / 16", that is, the allocation value EB(1,0,0), from the grayscale value Gg(mx+1,my,mz), and updates the grayscale value Gg(mx,my+1,mz) by subtracting the value obtained by multiplying the error E(mx,my,mz) by "6 / 16", that is, the allocation value EB(0,1,0). In other words, the reference example is different from the embodiment in that the error allocation unit 223 does not allocate the error E to the pixel Px in the Z-axis direction of the target pixel PxT in the error allocation process.

[0133] Fig. 9 as well as Fig.10 It is an explanatory diagram for explaining the display data generation process involved in the reference example.

[0134] In addition, Fig. 9 as well as Fig.10 In the example shown, it is assumed that "Mx=3", "My=3", "Mz=3", "M=3*3*3=27", and thus there are 27 pixels Px in the image forming space SP. Fig. 9 as well as Fig.10In the example shown, similarly to the embodiment, the grayscale value Gg-min is assumed to be "0", the grayscale value Gg-max is assumed to be "255", and the threshold value Th(mx, my, mz) is assumed to be "128". Fig. 9 as well as Fig.10 In the illustrated example, a case is assumed where all the M grayscale values ​​Gg(mx, my, mz) corresponding to the M pixels Px(mx, my, mz) constituting the image forming space SP are "128".

[0135] like Fig. 9 As shown, the image data acquisition unit 21 acquires image data GD in which all M grayscale values ​​Gg (mx, my, mz) are "128" during period t0. In the following, the image data GD during period t may be expressed as image data GD[t].

[0136] Next, the display data generating section 22 selects the pixel Px(1, 1, 1) as the target pixel PxT in the period t1 and performs the error diffusion process.

[0137] Specifically, first, the calculation processing unit 222 determines whether the grayscale value Gg(1, 1, 1) represented by the image data GD[t0] is greater than or equal to the threshold value Th(1, 1, 1) during the period t1. Fig. 9 as well as Fig.10 In the example shown, since the grayscale value Gg(1,1,1) represented by the image data GD[t0] is "128" and the threshold value Th(1,1,1) is "128", "Gg(1,1,1)≥Th(1,1,1)" holds. Therefore, the processing unit 222 sets the grayscale value GI(1,1,1) to the maximum grayscale value GI-1, that is, "255".

[0138] Then, the error allocator 223 calculates the error E(1, 1, 1) by subtracting the grayscale value Gg(1, 1, 1) represented by the image data GD[t0] from the value obtained by adding "1" to the grayscale value GI(1, 1, 1) during period t1. Fig. 9 as well as Fig.10 In the example shown, since the grayscale value GI (1, 1, 1) is "255" and the grayscale value Gg (1, 1, 1) represented by the image data GD [t0] is "128", the error E (1, 1, 1) becomes the value obtained by adding "1" to the highest grayscale value GI-1 and further subtracting the grayscale value Gg (1, 1, 1), that is, "128".

[0139] Next, the error allocator 223 calculates the distribution value EB(1,0,0) by multiplying the error E(1,1,1) and the distribution rate B(1,0,0) during the period t1, and changes the grayscale value Gg(2,1,1) by subtracting the distribution value EB(1,0,0) from the grayscale value Gg(2,1,1) represented by the image data GD[t0]. In addition, the error allocator 223 calculates the distribution value EB(0,1,0) by multiplying the error E(1,1,1) and the distribution rate B(0,1,0) during the period t1, and changes the grayscale value Gg(1,2,1) by subtracting the distribution value EB(0,1,0) from the grayscale value Gg(1,2,1) represented by the image data GD[t0].

[0140] exist Fig. 9 as well as Fig.10 In the example shown, since the error E(1, 1, 1) is "128", the grayscale value Gg(2, 1, 1) represented by the image data GD[t0] is "128", and the distribution rate B(1, 0, 0) is "10 / 16", the error distribution unit 223 calculates the distribution value EB(1, 0, 0) as "128*(10 / 16)", i.e., "80" based on formula (3), and further calculates the grayscale value Gg(2, 1, 1) represented by the image data GD[t1] as "128-80", i.e., "48" based on formula (2), thereby setting the grayscale value Gg(2, 1, 1) represented by the image data GD[t1] to "48".

[0141] Similarly, since the error E(1, 1, 1) is "128", the grayscale value Gg(1, 2, 1) represented by the image data GD[t0] is "128", and the distribution rate B(0, 1, 0) is "6 / 16", the error distribution unit 223 calculates the distribution value EB(0, 1, 0) as "128*(6 / 16)", i.e., "48", based on formula (3), and further calculates the grayscale value Gg(1, 2, 1) represented by the image data GD[t1] as "128-48", i.e., "80", based on formula (2), thereby setting the grayscale value Gg(1, 2, 1) represented by the image data GD[t1] to "80".

[0142] exist Fig. 9 as well as Fig.10 In the example shown, there is a pixel Px(2,1,1) in the +X direction of the pixel Px(1,1,1) selected as the target pixel PxT in the period t1. Therefore, the pixel selection unit 221 selects the pixel Px(2,1,1) as the target pixel PxT in the period t2. Then, the display data generation unit 22 performs the error diffusion process of setting the pixel Px(2,1,1) as the target pixel PxT in the period t2.

[0143] Specifically, first, the calculation processing unit 222 determines whether the grayscale value Gg(2, 1, 1) represented by the image data GD[t1] is greater than or equal to the threshold value Th(2, 1, 1) during the period t2. Fig. 9 as well as Fig.10 In the example shown, since the grayscale value Gg(2,1,1) represented by the image data GD[t1] is "48" and the threshold value Th(2,1,1) is "128", "Gg(2,1,1)<Th(2,1,1)" holds. Therefore, the processing unit 222 sets the grayscale value GI(2,1,1) to the minimum grayscale value GI-0, that is, "0".

[0144] Then, the error allocator 223 calculates the error E(2, 1, 1) by subtracting the grayscale value Gg(2, 1, 1) represented by the image data GD[t1] from the grayscale value GI(2, 1, 1) during the period t2. Fig. 9 as well as Fig.10 In the example shown, since the grayscale value GI(2, 1, 1) is "0" and the grayscale value Gg(2, 1, 1) represented by the image data GD[t1] is "48", the error E(2, 1, 1) becomes the value obtained by subtracting the grayscale value Gg(2, 1, 1) from the minimum grayscale value GI-0, that is, "-48".

[0145] Next, the error allocator 223 calculates the distribution value EB(1,0,0) by multiplying the error E(2,1,1) and the distribution rate B(1,0,0) during the period t2, and changes the grayscale value Gg(3,1,1) by subtracting the distribution value EB(1,0,0) from the grayscale value Gg(3,1,1) represented by the image data GD[t1]. In addition, the error allocator 223 calculates the distribution value EB(0,1,0) by multiplying the error E(2,1,1) and the distribution rate B(0,1,0) during the period t2, and changes the grayscale value Gg(2,2,1) by subtracting the distribution value EB(0,1,0) from the grayscale value Gg(2,2,1) represented by the image data GD[t1].

[0146] exist Fig. 9 as well as Fig.10In the example shown, since the error E(2, 1, 1) is "-48", the grayscale value Gg(3, 1, 1) represented by the image data GD[t1] is "128", and the distribution rate B(1, 0, 0) is "10 / 16", the error distribution unit 223 calculates the distribution value EB(1, 0, 0) as "(-48)*(10 / 16)", i.e., "-30", based on formula (3), and further calculates the grayscale value Gg(3, 1, 1) represented by the image data GD[t2] as "128-(-30)", i.e., "158", based on formula (2), thereby setting the grayscale value Gg(3, 1, 1) represented by the image data GD[t2] to "158".

[0147] Similarly, since the error E(2, 1, 1) is "-48", the grayscale value Gg(2, 2, 1) represented by the image data GD[t1] is "128", and the distribution rate B(0, 1, 0) is "6 / 16", the error distribution unit 223 calculates the distribution value EB(0, 1, 0) as "(-48)*(6 / 16)", or "-18", based on formula (3), and further calculates the grayscale value Gg(2, 2, 1) represented by the image data GD[t2] as "128-(-18)", or "146", based on formula (2), thereby setting the grayscale value Gg(2, 2, 1) represented by the image data GD[t2] to "146".

[0148] exist Fig. 9 as well as Fig.10 In the example shown, there is a pixel Px(3,1,1) in the +X direction of the pixel Px(2,1,1) selected as the target pixel PxT in the period t2. Therefore, the pixel selection unit 221 selects the pixel Px(3,1,1) as the target pixel PxT in the period t3. Then, the display data generation unit 22 performs the error diffusion process of setting the pixel Px(3,1,1) as the target pixel PxT in the period t3.

[0149] Specifically, first, the calculation processing unit 222 determines whether the grayscale value Gg(3, 1, 1) represented by the image data GD[t2] is greater than or equal to the threshold value Th(3, 1, 1) during the period t3. Fig. 9 as well as Fig.10 In the example shown, since the grayscale value Gg(3,1,1) represented by the image data GD[t2] is "158" and the threshold value Th(3,1,1) is "128", "Gg(3,1,1)≥Th(3,1,1)" holds. Therefore, the processing unit 222 sets the grayscale value GI(3,1,1) to the maximum grayscale value GI-1, that is, "255".

[0150] Then, the error allocator 223 calculates the error E(3, 1, 1) by subtracting the grayscale value Gg(3, 1, 1) represented by the image data GD[t2] from the value obtained by adding "1" to the grayscale value GI(3, 1, 1) during period t3. Fig. 9 as well as Fig.10 In the example shown, since the grayscale value GI (3, 1, 1) is "255" and the grayscale value Gg (3, 1, 1) represented by the image data GD [t2] is "158", the error E (3, 1, 1) becomes "98".

[0151] Next, the error allocator 223 calculates the distribution value EB(0,1,0) by multiplying the error E(3,1,1) and the distribution rate B(0,1,0) during period t3, and subtracts the distribution value EB(0,1,0) from the grayscale value Gg(3,2,1) represented by the image data GD[t2], thereby changing the grayscale value Gg(3,2,1). In addition, since there is no pixel Px in the +X direction of the pixel Px(3,1,1), the error allocator 223 does not calculate the distribution value EB(1,0,0) during period t3. Fig. 9 as well as Fig.10 In the example shown, since the error E(3, 1, 1) is "98" and the grayscale value Gg(3, 2, 1) represented by the image data GD[t2] is "128", the error distribution unit 223 sets the grayscale value Gg(3, 2, 1) represented by the image data GD[t3] to "91".

[0152] exist Fig. 9 as well as Fig.10 In the example shown, there is no pixel Px in the +X direction of the pixel Px (3, 1, 1) selected as the target pixel PxT in the period t3. On the other hand, there is a pixel Px in the +Y direction of the pixel Px (3, 1, 1) selected as the target pixel PxT in the period t3. Therefore, the pixel selection unit 221 selects the pixel Px (1, 2, 1) as the target pixel PxT in the period t4. Then, the display data generation unit 22 performs the error diffusion process of setting the pixel Px (1, 2, 1) as the target pixel PxT in the period t4.

[0153] Specifically, first, the calculation processing unit 222 determines whether the grayscale value Gg(1, 2, 1) represented by the image data GD[t3] is greater than or equal to the threshold value Th(1, 2, 1) during the period t4. Fig. 9 as well as Fig.10In the example shown, since the grayscale value Gg(1,2,1) represented by the image data GD[t3] is "80" and the threshold value Th(1,2,1) is "128", "Gg(1,2,1)<Th(1,2,1)" holds. Therefore, the processing unit 222 sets the grayscale value GI(1,2,1) to the minimum grayscale value GI-0, that is, "0".

[0154] Then, the error allocator 223 calculates the error E(1, 2, 1) by subtracting the grayscale value Gg(1, 2, 1) represented by the image data GD[t3] from the grayscale value GI(1, 2, 1) during the period t4. Fig. 9 as well as Fig.10 In the example shown, since the grayscale value GI (1, 2, 1) is "0" and the grayscale value Gg (1, 2, 1) represented by the image data GD [t3] is "80", the error E (1, 2, 1) becomes "-80".

[0155] Next, the error distribution unit 223 calculates the distribution value EB(1,0,0) by multiplying the error E(1,2,1) and the distribution rate B(1,0,0) during the period t4, and changes the grayscale value Gg(2,2,1) by subtracting the distribution value EB(1,0,0) from the grayscale value Gg(2,2,1) represented by the image data GD[t3]. In addition, the error distribution unit 223 calculates the distribution value EB(0,1,0) by multiplying the error E(1,2,1) and the distribution rate B(0,1,0) during the period t4, and changes the grayscale value Gg(1,3,1) by subtracting the distribution value EB(0,1,0) from the grayscale value Gg(1,3,1) represented by the image data GD[t3]. Fig. 9 as well as Fig.10 In the example shown, since the error E(1, 2, 1) is "-80", the grayscale value Gg(2, 2, 1) represented by the image data GD[t3] is "146", and the grayscale value Gg(1, 3, 1) represented by the image data GD[t3] is "128", the error allocation unit 223 sets the grayscale value Gg(2, 2, 1) represented by the image data GD[t4] to "189" and sets the grayscale value Gg(1, 3, 1) represented by the image data GD[t4] to "165".

[0156] Thereafter, the display data generating unit 22 performs error diffusion processing in which the pixels Px(2,2,1), Px(3,2,1), Px(1,3,1), Px(2,3,1), and Px(3,3,1) are set as the target pixels PxT during the period t5 to the period t9.

[0157] exist Fig. 9 as well as Fig.10 In the example shown, there is no pixel Px in the +X direction of the pixel Px (3, 3, 1) selected as the target pixel PxT in the period t9. In addition, there is no pixel Px in the +Y direction of the pixel Px (3, 3, 1) selected as the target pixel PxT in the period t9. On the other hand, there is a pixel Px in the +Z direction of the pixel Px (3, 3, 1) selected as the target pixel PxT in the period t9. Therefore, the pixel selection unit 221 selects the pixel Px (1, 1, 2) as the target pixel PxT in the period t10. Then, the display data generation unit 22 performs the error diffusion process of setting the pixel Px (1, 1, 2) as the target pixel PxT in the period t10.

[0158] Specifically, first, the calculation processing unit 222 determines whether the grayscale value Gg(1, 1, 2) represented by the image data GD[t9] is greater than or equal to the threshold value Th(1, 1, 2) during the period t10. Fig. 9 as well as Fig.10 In the example shown, since the grayscale value Gg(1,1,2) represented by the image data GD[t9] is "128" and the threshold value Th(1,1,2) is "128", "Gg(1,1,2)≥Th(1,1,2)" holds. Therefore, the processing unit 222 sets the grayscale value GI(1,1,2) to the maximum grayscale value GI-1, that is, "255".

[0159] Then, the error allocator 223 calculates the error E(1, 1, 2) by subtracting the grayscale value Gg(1, 1, 2) represented by the image data GD[t9] from the value obtained by adding "1" to the grayscale value GI(1, 1, 2) during period t10. Fig. 9 as well as Fig.10 In the example shown, since the grayscale value GI (1, 1, 2) is "255" and the grayscale value Gg (1, 1, 2) represented by the image data GD [t9] is "128", the error E (1, 1, 2) becomes "128".

[0160] Next, the error distribution unit 223 calculates the distribution value EB(1,0,0) by multiplying the error E(1,1,2) and the distribution rate B(1,0,0) during the period t10, and changes the grayscale value Gg(2,1,2) by subtracting the distribution value EB(1,0,0) from the grayscale value Gg(2,1,2) represented by the image data GD[t9]. In addition, the error distribution unit 223 calculates the distribution value EB(0,1,0) by multiplying the error E(1,1,2) and the distribution rate B(0,1,0) during the period t10, and changes the grayscale value Gg(1,2,2) by subtracting the distribution value EB(0,1,0) from the grayscale value Gg(1,2,2) represented by the image data GD[t9]. Fig. 9 as well as Fig.10 In the example shown, since the error E(1, 1, 2) is "128", the grayscale value Gg(2, 1, 2) represented by the image data GD[t9] is "128", and the grayscale value Gg(1, 2, 2) represented by the image data GD[t9] is "128", the error distribution unit 223 sets the grayscale value Gg(2, 1, 2) represented by the image data GD[t10] to "48" and sets the grayscale value Gg(1, 2, 2) represented by the image data GD[t10] to "80".

[0161] Thereafter, the display data generating section 22 performs the error diffusion process of setting the pixel Px(2, 1, 2) to the pixel Px(3, 3, 3) as the target pixel PxT during the period t11 to the period t27.

[0162] The result is, if Fig.10 As shown, in the reference example, in period t27, display data Img is generated such that grayscale value GI(1,1,1), grayscale value GI(3,1,1), grayscale value GI(2,2,1), grayscale value GI(1,3,1), grayscale value GI(3,3,1), grayscale value GI(1,1,2), grayscale value GI(3,1,2), grayscale value GI(2,2,2), grayscale value GI(1,3,2), grayscale value GI(3,3,2), grayscale value GI(1,1,3), grayscale value GI(3,1,3), grayscale value GI(2,2,3), grayscale value GI(1,3,3), and grayscale value GI(3,3,3) become the highest grayscale value GI-1, and grayscale values ​​GI(mx,my,mz) other than these become the lowest grayscale value GI-0. That is, in the reference example, it is possible to Fig.10 As shown, the display data Img is generated so that the dispersion of the dot-forming pixel Px-1 having the grayscale value GI (mx, my, mz) as the maximum grayscale value GI-1 on the plane parallel to the XY plane is high.

[0163] Fig.11 as well as Fig.12 2 is an explanatory diagram for explaining display data Img involved in a reference example generated in period t27. Fig.11 : is a diagram showing display data Img according to the reference example on a plane parallel to the XZ plane. Fig.12 It is a figure which shows the display data Img involved in a reference example on the plane parallel to the YZ plane.

[0164] like Fig.11 as well as Fig.12 As shown, in the reference example, at the positions X=X[1] and Y=Y[1], X=X[1] and Y=Y[3], X=X[2] and Y=Y[2], X=X[3] and Y=Y[1], and X=X[3] and Y=Y[3], a pixel Px-1 is formed with a grayscale value GI(mx, my, mz) being the highest grayscale value GI-1 in a continuous manner in the Z-axis direction. In other words, in the reference example, since only the error E in the XY plane is distributed in the error distribution process, and the error E in the Z-axis direction is not distributed, the configuration of the value of the display data Img in Z=Z[1], the configuration of the value of the display data Img in Z=Z[2], and the configuration of the value of the display data Img in Z=Z[3] are the same. Therefore, in the reference example, when the surface SF of the object Obj has a plane parallel to the XZ plane or a plane parallel to the YZ plane, a stripe-shaped pattern extending in the Z-axis direction is formed on the plane. In other words, in the reference example, it is not possible to improve the dispersion of the point-forming pixel Px-1 on the plane parallel to the XZ plane and the plane parallel to the YZ plane. Therefore, in the reference example, there is a problem that when an image G of intermediate grayscale is formed on the plane parallel to the XZ plane and the plane parallel to the YZ plane in the surface SF of the object Obj, the image quality of the image G is poor.

[0165] In addition, although the reference example uses Figure 8 The display data generation process is performed using the error diffusion data GK-Z1 as shown, but it is also possible to use Fig.13 The error diffusion data GK-Z2 shown in the figure can be used to perform display data generation processing, and the display data generation processing can also be performed using Fig.14 The display data generation process is performed based on the error diffusion data GK-Z3 as shown.

[0166] Fig.13 It is an explanatory diagram for explaining the error diffusion data GK-Z2.

[0167] like Fig.13As shown, the error diffusion data GK-Z2 is, when the pixel Px(mx, my, mz) is the object pixel PxT, the pixel Px(mx+1, my, mz), the pixel Px(mx, my+1, mz), the pixel Px(mx+1, my+1, mz) and the pixel Px(mx-1, my+1, mz) are designated as the data of the surrounding pixels PxS.

[0168] In addition, the error diffusion data GK-Z2 is data for determining each distribution rate B in such a manner that the distribution rate B(1, 0, 0) is larger than the distribution rate B(0, 1, 0), the distribution rate B(0, 1, 0) is larger than the distribution rate B(1, 1, 0), the distribution rate B(-1, 1, 0) is larger than the distribution rate B(1, 1, 0), and the distribution rate B(0, 1, 0) is larger than the distribution rate B(-1, 1, 0).

[0169] Fig.14 It is an explanatory diagram for explaining the error diffusion data GK-Z3.

[0170] like Fig.14 As shown, the error diffusion data GK-Z3 is, when the pixel Px(mx, my, mz) is the object pixel PxT, the pixels Px(mx+1, my, mz), pixel Px(mx+2, my, mz), pixel Px(mx-2, my+1, mz), pixel Px(mx-1, my+1, mz), pixel Px(mx, my+1, mz), pixel Px(mx+1, my+1, mz), pixel Px(mx+2, my+1, mz), pixel Px(mx-2, my+2, mz), pixel Px(mx-1, my+2, mz), pixel Px(mx, my+2, mz), pixel Px(mx+1, my+2, mz) and pixel Px(mx+2, my+2, mz) are designated as data of the surrounding pixels PxS.

[0171] In addition, the error diffusion data GK-Z3 is such that the distribution rate B(1,0,0) and the distribution rate B(0,1,0) are larger than the distribution rate B(2,0,0), the distribution rate B(-1,1,0), the distribution rate B(1,1,0) and the distribution rate B(0,2,0), and the distribution rate B(2,0,0), the distribution rate B(-1,1,0), the distribution rate B(1,1,0) and the distribution rate B(0,2,0) are larger than the distribution rate B(2,0,0), the distribution rate B(-1,1,0), the distribution rate B(1,1,0) and the distribution rate B(0,2,0). Data for determining each allocation rate B in a manner that makes allocation rate B(-2, 1, 0), allocation rate B(2, 1, 0), allocation rate B(-1, 2, 0), and allocation rate B(1, 2, 0) larger than allocation rate B(-2, 1, 0), allocation rate B(2, 1, 0), allocation rate B(-1, 2, 0), and allocation rate B(1, 2, 0) and larger than allocation rate B(-2, 2, 0) and allocation rate B(2, 2, 0).

[0172] As described above, the error diffusion data GK-Z2 and the error diffusion data GK-Z3 are data for determining that the distribution of the error E is performed only in the XY plane, but not in the Z-axis direction. Therefore, in the reference example, even when the error diffusion data GK-Z2 or the error diffusion data GK-Z3 is used instead of the error diffusion data GK-Z1 to perform the display data generation process, only the distribution of the error E in the XY plane is performed in the error distribution process, but not in the Z-axis direction. Therefore, in the reference example, even when the error diffusion data GK-Z2 or the error diffusion data GK-Z3 is used instead of the error diffusion data GK-Z1 to perform the display data generation process, the dispersion of the point formation pixel Px-1 cannot be improved on the plane parallel to the XZ plane and the plane parallel to the YZ plane, and the problem that the image quality of the image G formed on the surface SF of the object Obj is poor still exists.

[0173] 5. Display Data Generation Processing According to the Embodiment

[0174] In the following, in reference to Figures 15 to 18 At the same time, the display data generation processing performed in the recording system Sys is explained.

[0175] In addition, as mentioned above, the recording system Sys uses Figure 7 The error diffusion processing is performed using the error diffusion data GK shown in the figure. As described above, the error diffusion data GK is data that specifies the pixels Px(mx+1,my,mz), the pixels Px(mx,my+1,mz) and the pixels Px(mx,my,mz+1) as the surrounding pixels PxS when the pixel Px(mx,my,mz) is the target pixel PxT.

[0176] Furthermore, as described above, the error diffusion data GK is data that determines the distribution rate B(1,0,0), the distribution rate B(0,1,0), and the distribution rate B(0,0,1) in such a manner that the distribution rate B(1,0,0) is larger than the distribution rate B(0,1,0), and the distribution rate B(0,1,0) is larger than the distribution rate B(0,0,1). In other words, the present embodiment is different from the reference example in that the error allocator 223 allocates the error E to the pixel Px in the Z-axis direction of the target pixel PxT in the error allocation process. In addition, Figures 15 to 18 In the example shown, it is also assumed that the allocation ratio B(1, 0, 0) is "8 / 16", the allocation ratio B(0, 1, 0) is "5 / 16", and the allocation ratio B(0, 0, 1) is "3 / 16".

[0177] Fig.15 as well as Fig.16 It is an explanatory diagram for explaining the display data generation process involved in this embodiment.

[0178] In addition, Fig.15 as well as Fig.16 In the example shown, Fig. 9 as well as Fig.10 The example shown also assumes a case where "Mx=3", "My=3", "Mz=3", "M=3*3*3=27", and thus there are 27 pixels Px in the image forming space SP. Fig.15 as well as Fig.16 In the example shown, Fig. 9 as well as Fig.10 The example shown also assumes that the grayscale value Gg-min is "0", the grayscale value Gg-max is "255", and the threshold value Th(mx, my, mz) is "128". Fig.15 as well as Fig.16 In the illustrated example, a case is assumed where all the M grayscale values ​​Gg(mx, my, mz) corresponding to the M pixels Px(mx, my, mz) constituting the image forming space SP are "128".

[0179] like Fig.15 As shown, the image data acquisition unit 21 acquires image data GD[t0] in which all M grayscale values ​​Gg(mx, my, mz) are "128" during the period t0.

[0180] Next, the display data generating section 22 selects the pixel Px(1, 1, 1) as the target pixel PxT in the period t1 and performs the error diffusion process.

[0181] Specifically, first, the calculation processing unit 222 determines whether the grayscale value Gg(1, 1, 1) represented by the image data GD[t0] is greater than or equal to the threshold value Th(1, 1, 1) during the period t1. Fig.15 as well as Fig.16 In the example shown, since the grayscale value Gg(1,1,1) represented by the image data GD[t0] is "128" and the threshold value Th(1,1,1) is "128", "Gg(1,1,1)≥Th(1,1,1)" holds. Therefore, the processing unit 222 sets the grayscale value GI(1,1,1) to the maximum grayscale value GI-1, that is, "255".

[0182] Then, the error allocator 223 calculates the error E(1, 1, 1) by subtracting the grayscale value Gg(1, 1, 1) represented by the image data GD[t0] from the value obtained by adding "1" to the grayscale value GI(1, 1, 1) during period t1. Fig.15 as well as Fig.16 In the example shown, since the grayscale value GI (1, 1, 1) is "255" and the grayscale value Gg (1, 1, 1) represented by the image data GD [t0] is "128", the error E (1, 1, 1) becomes the value obtained by adding "1" to the highest grayscale value GI-1 and further subtracting the grayscale value Gg (1, 1, 1), that is, "128".

[0183] Next, the error allocator 223 calculates the distribution value EB(1,0,0) by multiplying the error E(1,1,1) and the distribution rate B(1,0,0) during the period t1, and changes the grayscale value Gg(2,1,1) by subtracting the distribution value EB(1,0,0) from the grayscale value Gg(2,1,1) represented by the image data GD[t0]. In addition, the error allocator 223 calculates the distribution value EB(0,1,0) by multiplying the error E(1,1,1) and the distribution rate B(0,1,0) during the period t1, and changes the grayscale value Gg(1,2,1) by subtracting the distribution value EB(0,1,0) from the grayscale value Gg(1,2,1) represented by the image data GD[t0]. In addition, the error distribution unit 223 calculates the distribution value EB(0, 0, 1) by multiplying the error E(1, 1, 1) and the distribution rate B(0, 0, 1) during period t1, and changes the grayscale value Gg(1, 1, 2) by subtracting the distribution value EB(0, 0, 1) from the grayscale value Gg(1, 1, 2) represented by the image data GD[t0].

[0184] exist Fig.15 as well as Fig.16In the example shown, since the error E(1, 1, 1) is "128", the grayscale value Gg(2, 1, 1) represented by the image data GD[t0] is "128", and the distribution rate B(1, 0, 0) is "8 / 16", the error distribution unit 223 calculates the distribution value EB(1, 0, 0) as "128*(8 / 16)", i.e., "64", based on formula (3), and further calculates the grayscale value Gg(2, 1, 1) represented by the image data GD[t1] as "128-64", i.e., "64", based on formula (2), thereby setting the grayscale value Gg(2, 1, 1) represented by the image data GD[t1] to "64".

[0185] Similarly, since the error E(1, 1, 1) is "128", the grayscale value Gg(1, 2, 1) represented by the image data GD[t0] is "128", and the distribution rate B(0, 1, 0) is "5 / 16", the error distribution unit 223 calculates the distribution value EB(0, 1, 0) as "128*(5 / 16)", i.e., "40", based on formula (3), and further calculates the grayscale value Gg(1, 2, 1) represented by the image data GD[t1] as "128-40", i.e., "88", based on formula (2), thereby setting the grayscale value Gg(1, 2, 1) represented by the image data GD[t1] to "88". Similarly, since the error E(1, 1, 1) is "128", the grayscale value Gg(1, 1, 2) represented by the image data GD[t0] is "128", and the distribution rate B(0, 0, 1) is "3 / 16", the error distribution unit 223 calculates the distribution value EB(0, 0, 1) as "128*(3 / 16)", i.e., "24", based on formula (3), and further calculates the grayscale value Gg(1, 1, 2) represented by the image data GD[t1] as "128-24", i.e., "104", based on formula (2), thereby setting the grayscale value Gg(1, 1, 2) represented by the image data GD[t1] to "104".

[0186] exist Fig.15 as well as Fig.16 In the example shown, there is a pixel Px(2,1,1) in the +X direction of the pixel Px(1,1,1) selected as the target pixel PxT in the period t1. Therefore, the pixel selection unit 221 selects the pixel Px(2,1,1) as the target pixel PxT in the period t2. Then, the display data generation unit 22 performs the error diffusion process of setting the pixel Px(2,1,1) as the target pixel PxT in the period t2.

[0187] Specifically, first, the calculation processing unit 222 determines whether the grayscale value Gg(2, 1, 1) represented by the image data GD[t1] is greater than or equal to the threshold value Th(2, 1, 1) during the period t2. Fig.15 as well as Fig.16 In the example shown, since the grayscale value Gg(2,1,1) represented by the image data GD[t1] is "64" and the threshold value Th(2,1,1) is "128", "Gg(2,1,1)<Th(2,1,1)" holds. Therefore, the processing unit 222 sets the grayscale value GI(2,1,1) to the minimum grayscale value GI-0, that is, "0".

[0188] Then, the error allocator 223 calculates the error E(2, 1, 1) by subtracting the grayscale value Gg(2, 1, 1) represented by the image data GD[t1] from the grayscale value GI(2, 1, 1) during the period t2. Fig.15 as well as Fig.16 In the example shown, since the grayscale value GI(2, 1, 1) is "0" and the grayscale value Gg(2, 1, 1) represented by the image data GD[t1] is "64", the error E(2, 1, 1) becomes the value obtained by subtracting the grayscale value Gg(2, 1, 1) from the minimum grayscale value GI-0, that is, "-64".

[0189] Next, the error allocator 223 calculates the distribution value EB(1,0,0) by multiplying the error E(2,1,1) and the distribution rate B(1,0,0) during the period t2, and changes the grayscale value Gg(3,1,1) by subtracting the distribution value EB(1,0,0) from the grayscale value Gg(3,1,1) represented by the image data GD[t1]. In addition, the error allocator 223 calculates the distribution value EB(0,1,0) by multiplying the error E(2,1,1) and the distribution rate B(0,1,0) during the period t2, and changes the grayscale value Gg(2,2,1) by subtracting the distribution value EB(0,1,0) from the grayscale value Gg(2,2,1) represented by the image data GD[t1]. In addition, the error distribution unit 223 calculates the distribution value EB(0, 0, 1) by multiplying the error E(2, 1, 1) and the distribution rate B(0, 0, 1) during period t2, and changes the grayscale value Gg(2, 1, 2) by subtracting the distribution value EB(0, 1, 0) from the grayscale value Gg(2, 1, 2) represented by the image data GD[t1].

[0190] exist Fig.15 as well as Fig.16In the example shown, since the error E(2, 1, 1) is "-64", the grayscale value Gg(3, 1, 1) represented by the image data GD[t1] is "128", and the distribution rate B(1, 0, 0) is "8 / 16", the error distribution unit 223 calculates the distribution value EB(1, 0, 0) as "(-64)*(8 / 16)", i.e., "-32", based on formula (3), and further calculates the grayscale value Gg(3, 1, 1) represented by the image data GD[t2] as "128-(-32)", i.e., "160", based on formula (2), thereby setting the grayscale value Gg(3, 1, 1) represented by the image data GD[t2] to "160".

[0191] Similarly, since the error E(2, 1, 1) is "-64", the grayscale value Gg(2, 2, 1) represented by the image data GD[t1] is "128", and the distribution rate B(0, 1, 0) is "5 / 16", the error distribution unit 223 calculates the distribution value EB(0, 1, 0) as "(-64)*(5 / 16)", i.e., "-20", based on formula (3), and further calculates the grayscale value Gg(2, 2, 1) represented by the image data GD[t2] as "128-(-20)", i.e., "148", based on formula (2), thereby setting the grayscale value Gg(2, 2, 1) represented by the image data GD[t2] to "148".

[0192] Similarly, since the error E(2, 1, 1) is "-64", the grayscale value Gg(2, 1, 2) represented by the image data GD[t1] is "128", and the distribution rate B(0, 0, 1) is "3 / 16", the error distribution unit 223 calculates the distribution value EB(0, 0, 1) as "(-64)*(3 / 16)", or "-12", based on formula (3), and further calculates the grayscale value Gg(2, 1, 2) represented by the image data GD[t2] as "128-(-12)", or "140", based on formula (2), thereby setting the grayscale value Gg(2, 1, 2) represented by the image data GD[t2] to "140".

[0193] exist Fig.15 as well as Fig.16 In the example shown, there is a pixel Px(3,1,1) in the +X direction of the pixel Px(2,1,1) selected as the target pixel PxT in the period t2. Therefore, the pixel selection unit 221 selects the pixel Px(3,1,1) as the target pixel PxT in the period t3. Then, the display data generation unit 22 performs the error diffusion process of setting the pixel Px(3,1,1) as the target pixel PxT in the period t3.

[0194] Specifically, first, the calculation processing unit 222 determines whether the grayscale value Gg(3, 1, 1) represented by the image data GD[t2] is greater than or equal to the threshold value Th(3, 1, 1) during the period t3. Fig.15 as well as Fig.16 In the example shown, since the grayscale value Gg(3,1,1) represented by the image data GD[t2] is "160" and the threshold value Th(3,1,1) is "128", "Gg(3,1,1)≥Th(3,1,1)" holds. Therefore, the processing unit 222 sets the grayscale value GI(3,1,1) to the maximum grayscale value GI-1, that is, "255".

[0195] Then, the error allocator 223 calculates the error E(3, 1, 1) by subtracting the grayscale value Gg(3, 1, 1) represented by the image data GD[t2] from the value obtained by adding "1" to the grayscale value GI(3, 1, 1) during period t3. Fig. 9 as well as Fig.10 In the example shown, since the grayscale value GI (3, 1, 1) is "255" and the grayscale value Gg (3, 1, 1) represented by the image data GD [t2] is "160", the error E (3, 1, 1) becomes "96".

[0196] Next, the error allocator 223 calculates the distribution value EB(0,1,0) by multiplying the error E(3,1,1) and the distribution rate B(0,1,0) during the period t3, and changes the grayscale value Gg(3,2,1) by subtracting the distribution value EB(0,1,0) from the grayscale value Gg(3,2,1) represented by the image data GD[t2]. In addition, the error allocator 223 calculates the distribution value EB(0,0,1) by multiplying the error E(3,1,1) and the distribution rate B(0,0,1) during the period t3, and changes the grayscale value Gg(3,1,2) by subtracting the distribution value EB(0,0,1) from the grayscale value Gg(3,1,2) represented by the image data GD[t2]. In addition, since there is no pixel Px in the +X direction of the pixel Px (3, 1, 1), the error allocator 223 does not calculate the distribution value EB (1, 0, 0) during the period t3. Fig.15 as well as Fig.16 In the example shown, since the error E(3, 1, 1) is "96", the grayscale value Gg(3, 2, 1) represented by the image data GD[t2] is "128", and the grayscale value Gg(3, 1, 2) represented by the image data GD[t2] is "128", the error allocation unit 223 sets the grayscale value Gg(3, 2, 1) represented by the image data GD[t3] to "98" and sets the grayscale value Gg(3, 1, 2) represented by the image data GD[t3] to "110".

[0197] exist Fig.15 as well as Fig.16 In the example shown, there is no pixel Px in the +X direction of the pixel Px (3, 1, 1) selected as the target pixel PxT in the period t3. On the other hand, there is a pixel Px in the +Y direction of the pixel Px (3, 1, 1) selected as the target pixel PxT in the period t3. Therefore, the pixel selection unit 221 selects the pixel Px (1, 2, 1) as the target pixel PxT in the period t4. Then, the display data generation unit 22 performs the error diffusion process of setting the pixel Px (1, 2, 1) as the target pixel PxT in the period t4.

[0198] Specifically, first, the calculation processing unit 222 determines whether the grayscale value Gg(1, 2, 1) represented by the image data GD[t3] is greater than or equal to the threshold value Th(1, 2, 1) during the period t4. Fig.15 as well as Fig.16 In the example shown, since the grayscale value Gg(1,2,1) represented by the image data GD[t3] is "88" and the threshold value Th(1,2,1) is "128", "Gg(1,2,1)<Th(1,2,1)" holds. Therefore, the processing unit 222 sets the grayscale value GI(1,2,1) to the minimum grayscale value GI-0, that is, "0".

[0199] Then, the error allocator 223 calculates the error E(1, 2, 1) by subtracting the grayscale value Gg(1, 2, 1) represented by the image data GD[t3] from the grayscale value GI(1, 2, 1) during the period t4. Fig. 9 as well as Fig.10 In the example shown, since the grayscale value GI (1, 2, 1) is "0" and the grayscale value Gg (1, 2, 1) represented by the image data GD [t3] is "88", the error E (1, 2, 1) becomes "-88".

[0200] Next, the error allocator 223 calculates the distribution value EB(1,0,0) by multiplying the error E(1,2,1) and the distribution rate B(1,0,0) during the period t4, and changes the grayscale value Gg(2,2,1) by subtracting the distribution value EB(1,0,0) from the grayscale value Gg(2,2,1) represented by the image data GD[t3]. In addition, the error allocator 223 calculates the distribution value EB(0,1,0) by multiplying the error E(1,2,1) and the distribution rate B(0,1,0) during the period t4, and changes the grayscale value Gg(1,3,1) by subtracting the distribution value EB(0,1,0) from the grayscale value Gg(1,3,1) represented by the image data GD[t3]. Furthermore, the error allocator 223 calculates the distribution value EB(0,0,1) by multiplying the error E(1,2,1) and the distribution rate B(0,0,1) during the period t4, and subtracts the distribution value EB(0,0,1) from the grayscale value Gg(1,2,2) represented by the image data GD[t3], thereby changing the grayscale value Gg(1,2,2). Fig.15 as well as Fig.16 In the example shown, since the error E(1, 2, 1) is "-88", the grayscale value Gg(2, 2, 1) represented by the image data GD[t3] is "148", the grayscale value Gg(1, 3, 1) represented by the image data GD[t3] is "128", and the grayscale value Gg(1, 2, 2) represented by the image data GD[t3] is "128", the error distribution unit 223 sets the grayscale value Gg(2, 2, 1) represented by the image data GD[t4] to "192", sets the grayscale value Gg(1, 3, 1) represented by the image data GD[t4] to "156", and sets the grayscale value Gg(1, 2, 2) represented by the image data GD[t4] to "145".

[0201] Thereafter, the display data generating unit 22 performs error diffusion processing in which the pixels Px(2,2,1), Px(3,2,1), Px(1,3,1), Px(2,3,1), and Px(3,3,1) are set as the target pixels PxT during the period t5 to the period t9.

[0202] exist Fig.15 as well as Fig.16In the example shown, there is no pixel Px in the +X direction of the pixel Px (3, 3, 1) selected as the target pixel PxT in the period t9. In addition, there is no pixel Px in the +Y direction of the pixel Px (3, 3, 1) selected as the target pixel PxT in the period t9. On the other hand, there is a pixel Px in the +Z direction of the pixel Px (3, 3, 1) selected as the target pixel PxT in the period t9. Therefore, the pixel selection unit 221 selects the pixel Px (1, 1, 2) as the target pixel PxT in the period t10. Then, the display data generation unit 22 performs the error diffusion process of setting the pixel Px (1, 1, 2) as the target pixel PxT in the period t10.

[0203] Specifically, first, the calculation processing unit 222 determines whether the grayscale value Gg(1, 1, 2) represented by the image data GD[t9] is greater than or equal to the threshold value Th(1, 1, 2) during the period t10. Fig.15 as well as Fig.16 In the example shown, since the grayscale value Gg(1,1,2) represented by the image data GD[t9] is "104" and the threshold value Th(1,1,2) is "128", "Gg(1,1,2)<Th(1,1,2)" holds. Therefore, the processing unit 222 sets the grayscale value GI(1,1,2) to the minimum grayscale value GI-0, that is, "0".

[0204] Then, the error allocator 223 calculates the error E(1, 1, 2) by subtracting the grayscale value Gg(1, 1, 2) represented by the image data GD[t9] from the grayscale value GI(1, 1, 2) during the period t10. Fig.15 as well as Fig.16 In the example shown, since the grayscale value GI (1, 1, 2) is "0" and the grayscale value Gg (1, 1, 2) represented by the image data GD [t9] is "104", the error E (1, 1, 2) becomes "-104".

[0205] Next, the error allocator 223 calculates the distribution value EB(1,0,0) by multiplying the error E(1,1,2) and the distribution rate B(1,0,0) during the period t10, and changes the grayscale value Gg(2,1,2) by subtracting the distribution value EB(1,0,0) from the grayscale value Gg(2,1,2) represented by the image data GD[t9]. In addition, the error allocator 223 calculates the distribution value EB(0,1,0) by multiplying the error E(1,1,2) and the distribution rate B(0,1,0) during the period t10, and changes the grayscale value Gg(1,2,2) by subtracting the distribution value EB(0,1,0) from the grayscale value Gg(1,2,2) represented by the image data GD[t9]. Furthermore, the error allocator 223 calculates the distribution value EB(0,0,1) by multiplying the error E(1,1,2) and the distribution rate B(0,0,1) during the period t10, and subtracts the distribution value EB(0,0,1) from the grayscale value Gg(1,1,3) represented by the image data GD[t9], thereby changing the grayscale value Gg(1,1,3). Fig.15 as well as Fig.16 In the example shown, since the error E(1, 1, 2) is "-104", the grayscale value Gg(2, 1, 2) represented by the image data GD[t9] is "140", the grayscale value Gg(1, 2, 2) represented by the image data GD[t9] is "145", and the grayscale value Gg(1, 1, 3) represented by the image data GD[t9] is "128", the error distribution unit 223 sets the grayscale value Gg(2, 1, 2) represented by the image data GD[t10] to "192", sets the grayscale value Gg(1, 2, 2) represented by the image data GD[t10] to "178", and sets the grayscale value Gg(1, 1, 3) represented by the image data GD[t10] to "148".

[0206] Thereafter, the display data generating section 22 performs the error diffusion process of setting the pixel Px(2, 1, 2) to the pixel Px(3, 3, 3) as the target pixel PxT during the period t11 to the period t27.

[0207] The result is, if Fig.16As shown, in the present embodiment, in the period t27, display data Img is generated such that grayscale value GI(1,1,1), grayscale value GI(3,1,1), grayscale value GI(2,2,1), grayscale value GI(1,3,1), grayscale value GI(3,3,1), grayscale value GI(2,1,2), grayscale value GI(1,2,2), grayscale value GI(3,2,2), grayscale value GI(2,3,2), grayscale value GI(1,1,3), grayscale value GI(3,1,3), grayscale value GI(2,2,3), grayscale value GI(1,3,3), and grayscale value GI(3,3,3) become the highest grayscale value GI-1, and the grayscale values ​​GI(mx,my,mz) other than these become the lowest grayscale value GI-0. That is, in the present embodiment, as Fig.10 As shown, it is possible to generate display data Img such that the dispersion of the dot-forming pixel Px-1 having the grayscale value GI (mx, my, mz) as the maximum grayscale value GI-1 on a plane parallel to the XY plane is high.

[0208] Fig.17 as well as Fig.18 2 is an explanatory diagram for explaining the display data Img involved in this embodiment generated in the period t27. Fig.17 2 is a diagram showing display data Img according to the present embodiment on a plane parallel to the XZ plane. Fig.18 It is a diagram showing the display data Img involved in this embodiment on a plane parallel to the YZ plane.

[0209] like Fig.17 as well as Fig.18 As shown, in the present embodiment, in the error distribution process, in addition to the distribution of the error E in the XY plane, the distribution of the error E in the Z-axis direction is also implemented. Therefore, in the present embodiment, in addition to the plane parallel to the XY plane, the dispersion of the point-forming pixel Px-1 can be improved on the plane parallel to the XZ plane and the plane parallel to the YZ plane. That is, in the present embodiment, when the intermediate grayscale image G is formed on the plane parallel to the XZ plane and the plane parallel to the YZ plane in addition to the plane parallel to the XY plane on the surface SF of the object Obj, the image quality of the image G can be improved compared with the reference example.

[0210] 6. Effects of this embodiment

[0211] Fig.19: is an explanatory diagram for explaining the spatial frequency characteristics of a plurality of dots forming a pixel Px-1 corresponding to the highest grayscale value GI-1 among a plurality of grayscale values ​​GI (mx, my, mz) represented by display data Img generated based on the image data GD when the grayscale value Gg (mx, my, mz) represented by the image data GD is the middle grayscale value Gg-mid. Specifically, Fig.19 A curve FB is shown, which represents the relationship between the spatial frequency of the distribution of the pixel Px-1 formed by the multiple points on the predetermined plane and the amount of each frequency component of the distribution of the pixel Px-1 formed by the multiple points on the predetermined plane, when the grayscale value Gg (mx, my, mz) represented by the image data GD is the intermediate grayscale value Gg-mid and the display data Img is generated based on the image data GD, and the image forming space SP is cut off by a predetermined plane and the distribution of the pixel Px-1 formed by the multiple points on the predetermined plane is converted from the spatial domain to the spatial frequency domain.

[0212] Here, the intermediate grayscale value Gg-mid refers to a grayscale value between the grayscale value Gg-min and the grayscale value Gg-max. More specifically, the intermediate grayscale value Gg-mid may be a grayscale value represented by the following equation (7), for example.

[0213] (1-γ3)*Gg-min+γ3*Gg-max≤Gg-mid

[0214] ≤(1-γ4)*Gg-min+γ4*Gg-max...Equation (7)

[0215] In the formula (7), the value γ3 is a real number satisfying, for example, “0.2≤γ3≤0.5”, and the value γ4 is a real number satisfying, for example, “0.5≤γ4≤0.7”.

[0216] like Fig.19 As shown, the curve FB has the following characteristics, that is, among the spatial frequencies that form the distribution of the pixel Px-1 at a plurality of points on a predetermined plane, the frequency component between the highest frequency fmax and the intermediate frequency fmid, which is the highest frequency, is greater than the frequency component between the lowest frequency fmin and the intermediate frequency fmid, which is the lowest frequency. Here, the intermediate frequency fmid refers to a frequency between the intermediate frequency fmid and the highest frequency fmax. More specifically, the intermediate frequency fmid may also be a frequency represented by "fmid = {fmin + fmax} ÷ 2", for example.

[0217] Hereinafter, such a characteristic that the frequency components between the highest frequency fmax and the intermediate frequency fmid in the spatial frequency domain are more than the frequency components between the lowest frequency fmin and the intermediate frequency fmid is referred to as a “predetermined spatial frequency characteristic”.

[0218] In addition, if Fig.19 As shown, the curve FB has a peak at the maximum frequency fmax side compared to the intermediate frequency fmid. Therefore, in this embodiment, the situation where the curve FB has a peak at the maximum frequency fmax side compared to the intermediate frequency fmid can also be called a "predetermined spatial frequency characteristic".

[0219] More specifically, in this embodiment, the predetermined spatial frequency characteristic refers to a blue noise characteristic. However, in this embodiment, it is not limited to the case where the predetermined spatial frequency characteristic is a blue noise characteristic. In this embodiment, the predetermined spatial frequency characteristic only needs to be a frequency characteristic having more frequency components on the high frequency side in the spatial frequency domain compared to the white noise characteristic. For example, in this embodiment, the predetermined spatial frequency characteristic may also be a purple noise characteristic.

[0220] In addition, in the present embodiment, two planes, namely, plane PL1 and plane PL2, can be used as predetermined planes. Specifically, in the present embodiment, when the grayscale value Gg (mx, my, mz) represented by the image data GD is the intermediate grayscale value Gg-mid and display data Img is generated based on the image data GD, the distribution of the plurality of points forming pixels Px-1 on the plane PL1 that cuts the image forming space SP has a predetermined spatial frequency characteristic, and the distribution of the plurality of points forming pixels Px-1 on the plane PL2 that cuts the image forming space SP has a predetermined spatial frequency characteristic.

[0221] Here, plane PL1 and plane PL2 are planes that are not parallel to each other. In other words, the normal vector of plane PL1 intersects the normal vector of plane PL2. For example, the normal vector of plane PL1 and the normal vector of plane PL2 may be orthogonal. Specifically, plane PL1 may be a plane having a normal vector extending in the Z-axis direction. More specifically, plane PL1 may be a plane parallel to the XY plane. In addition, plane PL2 may be a plane having a normal vector extending in the X-axis direction. More specifically, plane PL2 may be a plane parallel to the YZ plane.

[0222] As described above, according to the present embodiment, points can be arranged on the surface SF of the object Obj in such a manner that the distribution of the pixels Px-1 formed by the plurality of points on the plane PL1 has a frequency characteristic in which the high-frequency components higher than the intermediate frequency fmid are more than the low-frequency components lower than the intermediate frequency fmid in the spatial frequency domain, and further, the distribution of the pixels Px-1 formed by the plurality of points on the plane PL2 which is not parallel to the plane PL1 has a frequency characteristic in which the high-frequency components higher than the intermediate frequency fmid are more than the low-frequency components lower than the intermediate frequency fmid in the spatial frequency domain. Therefore, according to the present embodiment, even in the case where the shape of the object Obj has a shape other than a two-dimensional plane, the dispersion of the arrangement of the points on the surface of the object Obj can be improved.

[0223] Furthermore, in the present embodiment, the error allocating unit 223 allocates the error E in the target pixel PxT not only to the X-axis direction and the Y-axis direction but also to the Z-axis direction. Therefore, according to the present embodiment, in the surface SF of the target object Obj, in addition to the plane parallel to the XY plane, the plane parallel to the XZ plane and the plane parallel to the YZ plane can also improve the dispersion of the arrangement of the points.

[0224] In addition, in the present embodiment, the target pixel of the error diffusion process is first shifted in the +X direction, and then when it becomes the largest in the +X direction (there is no other pixel closer to the +X direction than the pixel), one pixel is adjacent in the +Y direction and the pixel is shifted to the smallest pixel in the +X direction again. And, when it becomes the largest in the +X direction and the +Y direction (there is no other pixel closer to the +X direction than the pixel, and there is no other pixel closer to the +Y direction than the pixel), one pixel is adjacent in the +Z direction and the pixel is shifted to the smallest pixel in the +X direction and the +Y direction again. That is, although the target pixel of the error diffusion process is shifted in the +X direction, the +Y direction, and the +Z direction, the priority at this time is made to be the highest in the +X direction, the second highest in the +Y direction, and the lowest in the +Z direction.

[0225] Furthermore, at this time, the allocation rate B(1, 0, 0) corresponding to the allocation rate in the +X direction is made the largest, the allocation rate B(0, 1, 0) corresponding to the allocation rate in the +Y direction is made the second largest, and the allocation rate B(0, 0, 1) corresponding to the allocation rate in the +Z direction is made the smallest. In other words, the higher the priority of the direction when shifting the target pixel, the larger the allocation rate.

[0226] The reason is as follows. When error diffusion processing is performed on a certain target pixel Px (mx, my, mz), the error diffusion processing performed so far will allocate the error of the three pixels Px (mx-1, my, mz), Px (mx, my-1, mz), and Px (mx, my, mz-1) to the target pixel Px (mx, my, mz). In this case, when the priority is decreased in the order of +X direction, +Y direction, and +Z direction as described above, among the three pixels, error diffusion processing is first performed on pixel Px (mx, my, mz-1), then error diffusion processing is performed on pixel Px (mx, my-1, mz), and finally error diffusion processing is performed on pixel Px (mx-1, my, mz). Since the error diffusion processing is more accurate as the number of processed pixels increases, the error diffusion processing for the pixel Px(mx, my-1, mz) is more reliable than the error diffusion processing for the pixel Px(mx, my, mz-1), and the error diffusion processing for the pixel Px(mx-1, my, mz) is more reliable than the error diffusion processing for the pixel Px(mx, my-1, mz). Therefore, the error assigned to the object pixel Px(mx, my, mz) is preferably the largest ratio assigned to the pixel Px(mx-1, my, mz) with the highest reliability, and the smallest ratio assigned to the pixel Px(mx, my, mz-1) with the lowest reliability.

[0227] In addition, in the present embodiment, the number of times the error E is distributed from other pixels Px to the pixel Px (mx, my+1, mz) is sometimes greater than the number of times the error E is distributed from other pixels Px to the pixel Px (mx+1, my, mz). Moreover, in the present embodiment, the distribution rate B (1, 0, 0) is determined to be larger than the distribution rate B (0, 1, 0). Therefore, in the present embodiment, the uniformity of the distribution of the errors E to the M pixels Px in the image forming space SP can be improved compared to the mode in which the distribution rate B (1, 0, 0) is less than the distribution rate B (0, 1, 0).

[0228] In addition, in the present embodiment, the number of times the error E is distributed from other pixels Px to the pixel Px (mx, my, mz+1) is sometimes greater than the number of times the error E is distributed from other pixels Px to the pixel Px (mx, my+1, mz). In contrast, in the present embodiment, the distribution rate B (0, 1, 0) is determined to be larger than the distribution rate B (0, 0, 1). Therefore, in the present embodiment, the uniformity of the distribution of the errors E to the M pixels Px in the image forming space SP can be improved compared to a method in which the distribution rate B (0, 1, 0) is less than the distribution rate B (0, 0, 1).

[0229] 7. Summary of implementation methods

[0230] As described above, the terminal device 1 involved in the present embodiment is characterized in that it comprises: an image data acquisition unit 21, which acquires image data GD representing the grayscale value Gg (mx, my, mz) of the image Gf that should be displayed by each pixel in the M pixels Px in the image forming space SP when the image Gf is displayed in the three-dimensional image forming space SP; a display data generation unit 22, which generates display data Img by quantizing the grayscale value Gg (mx, my, mz) represented by the image data GD, and the display data generation unit 22 comprises: a pixel selection unit 221, which selects a pixel Px (mx, my, mz) from the M pixels Px; and an error allocation unit 223, which allocates the grayscale value Gg (mx, my, mz) based on the grayscale value Gg (mx, my, mz) corresponding to the pixel Px (mx, my, mz). The error E(mx, my, mz) caused by the quantization of the corresponding grayscale value Gg(mx, my, mz) is distributed to the pixel Px(mx+1, my, mz) located in the +X direction of the pixel Px(mx, my, mz) at a distribution rate B(1, 0, 0), and is distributed to the pixel Px(mx, my+1, mz) located in the +Y direction of the pixel Px(mx, my, mz) at a distribution rate B(0, 1, 0), and is distributed to the pixel Px(mx, my+1, mz) located in the +Z direction of the pixel Px(mx, my, mz) at a distribution rate B(0, 0, 1), where the +Y direction is a direction intersecting the +X direction, and the +Z direction is a direction different from the extension direction of the XY plane defined by the +X direction and the +Y direction.

[0231] That is, in this embodiment, the error allocator 223 allocates the error E(mx, my, mz) in the +Z direction in addition to the error E(mx, my, mz) in the XY plane. Therefore, according to this embodiment, even when the image G is formed for the surface SF of the object Obj having a three-dimensional shape, the occurrence of graininess in the image G can be suppressed.

[0232] In addition, in the present embodiment, the terminal device 1 is an example of an “image processing device”, the image data acquisition unit 21 is an example of an “acquisition unit”, the display data generation unit 22 is an example of a “generation unit”, the pixel selection unit 221 is an example of a “selection unit”, the error allocation unit 223 is an example of an “allocation unit”, the image formation space SP is an example of a “three-dimensional space”, the pixel Px(mx, my, mz) is an example of “one pixel”, and the pixel Px(mx+1, my, mz) is an example of a “first pixel”. Example, pixel Px(mx, my+1, mz) is an example of a “second pixel”, pixel Px(mx, my, mz+1) is an example of a “third pixel”, +X direction is an example of a “first direction”, +Y direction is an example of a “second direction”, +Z direction is an example of a “third direction”, distribution rate B(1, 0, 0) is an example of a “first distribution rate”, distribution rate B(0, 1, 0) is an example of a “second distribution rate”, and distribution rate B(0, 0, 1) is an example of a “third distribution rate”.

[0233] In addition, in the terminal device 1 involved in the present embodiment, the feature can also be set that when any one of the M pixels Px in the image forming space SP exists in the +X direction of the pixel Px (mx, my, mz), the pixel selection unit 221 selects other pixels Px located in the +X direction of the pixel Px (mx, my, mz) after selecting the pixel Px (mx, my, mz).

[0234] In addition, in the terminal device 1 involved in the present embodiment, the feature can also be set as that the M pixels Px in the image forming space SP include (My*Mz) pixel columns PxL extending in the +X direction, and when there is no pixel Px in the M pixels Px in the image forming space SP in the +X direction of the pixel Px(mx, my, mz), the pixel selection unit 221 selects other pixels Px from the pixel column PxL[my+1][mz] in the +Y direction of the pixel column PxL[my][mz] including the pixel Px(mx, my, mz) after selecting the pixel Px(mx, my, mz).

[0235] In the present embodiment, the pixel column PxL[my][mz] is an example of “one pixel column”, and the pixel column PxL[my+1][mz] is an example of “another pixel column”.

[0236] In addition, in the terminal device 1 involved in the present embodiment, the feature can also be set as that the M pixels Px in the image forming space SP include Mz pixel planes PxP parallel to the XY plane, and when there is no pixel Px in the M pixels Px in the image forming space SP in the +X direction of the pixel Px(mx, my, mz), and there is no pixel column PxL in the (My*Mz) pixel columns PxL in the image forming space SP in the +Y direction of the pixel column PxL[my][mz] including the pixel Px(mx, my, mz), the pixel selection unit 221 selects other pixels Px from the pixel plane PxP[mz+1] located in the +Z direction of the pixel plane PxP[mz] including the pixel Px(mx, my, mz) after selecting the pixel Px(mx, my, mz).

[0237] That is, in the present embodiment, after the pixel selection unit 221 completes the selection of the pixel Px in the pixel plane PxP[mz], it selects the pixel Px from the pixel plane PxP[mz+1]. Therefore, according to the present embodiment, the error diffusion process can be performed on the M pixels Px in the three-dimensional image forming space SP as the object, so that even when the image G is formed for the surface SF of the object Obj having a three-dimensional shape, the occurrence of graininess in the image G can be suppressed.

[0238] In addition, in the present embodiment, the pixel plane PxP[mz] is an example of “one pixel plane”, and the pixel plane PxP[mz+1] is an example of “another pixel plane”.

[0239] In the terminal device 1 according to the present embodiment, the distribution rate B(1, 0, 0) may be characterized as being larger than the distribution rate B(0, 1, 0) and the distribution rate B(0, 0, 1).

[0240] Therefore, according to this embodiment, compared with a method in which the distribution rate B(1,0,0) is the distribution rate B(0,1,0) or less than the distribution rate B(0,0,1), the uniformity of the distribution of the errors E for the M pixels Px in the image forming space SP can be improved.

[0241] Furthermore, in the terminal device 1 according to the present embodiment, the allocation rate B(0, 1, 0) may be characterized as being larger than the allocation rate B(0, 0, 1).

[0242] Therefore, according to the present embodiment, the uniformity of the distribution of the errors E for the M pixels Px in the image forming space SP can be improved compared to a configuration in which the distribution rate B(0, 1, 0) is equal to or lower than the distribution rate B(0, 0, 1).

[0243] In addition, in the terminal device 1 involved in the present embodiment, the characteristics can also be set as follows: pixel Px(mx+1, my, mz) is a pixel Px adjacent to pixel Px(mx, my, mz) in the +X direction of pixel Px(mx, my, mz), pixel Px(mx, my+1, mz) is a pixel Px adjacent to pixel Px(mx, my, mz) in the +Y direction of pixel Px(mx, my, mz), and pixel Px(mx, my, mz+1) is a pixel Px adjacent to pixel Px(mx, my, mz) in the +Z direction of pixel Px(mx, my, mz).

[0244] Furthermore, in the terminal device 1 according to the present embodiment, the +X direction may be characterized as being a direction orthogonal to the +Y direction and the +Z direction, and the +Y direction may be a direction orthogonal to the +Z direction.

[0245] In addition, the recording device 5 involved in the present embodiment is characterized in that it forms an image G for an object Obj of a three-dimensional shape, and includes: a head unit 7 that ejects ink; and a recording control unit 6 that controls the ejection of ink from the head unit 7 to form an image G for the object Obj by using a plurality of points whose configuration is determined by using an error diffusion process using an error diffusion method and a plurality of points formed by the ink ejected from the head unit 7, and the recording control unit 6 controls the ejection of ink from the head unit 7 so that when the object Obj has a plane PL1, the distribution of the plurality of points on the plane PL1 has a frequency characteristic in which high-frequency components higher than the intermediate frequency fmid are more than low-frequency components lower than the intermediate frequency fmid in the spatial frequency domain, and when the object Obj has a plane PL2 that is not parallel to the plane PL1, the distribution of the plurality of points on the plane PL2 has a frequency characteristic in which high-frequency components higher than the intermediate frequency fmid are more than low-frequency components lower than the intermediate frequency fmid in the spatial frequency domain.

[0246] Therefore, according to the present embodiment, even when the shape of the target object Obj has a shape other than a two-dimensional plane, it is possible to improve the dispersion of the arrangement of points on the surface of the target object Obj.

[0247] In addition, in the present embodiment, the object object Obj is an example of an “object object”, the ink is an example of a “liquid”, the recording control unit 6 is an example of a “control unit”, the plane PL1 is an example of a “first surface”, the plane PL2 is an example of a “second surface”, and the intermediate frequency fmid is an example of a “predetermined frequency”.

[0248] In addition, in the recording device 5 involved in this embodiment, the characteristics can also be set as that the distribution of multiple points on the plane PL1 has a frequency characteristic different from the white noise characteristic in the spatial frequency domain, and the distribution of multiple points on the plane PL2 has a frequency characteristic different from the white noise characteristic in the spatial frequency domain.

[0249] In the recording device 5 according to the present embodiment, the distribution of the plurality of points on the plane PL1 may be characterized as having a blue noise characteristic in the spatial frequency domain, and the distribution of the plurality of points on the plane PL2 may be characterized as having a blue noise characteristic in the spatial frequency domain.

[0250] B. Modification

[0251] The above-described embodiments can be modified in various ways. Specific modified embodiments are exemplified below. Two or more embodiments arbitrarily selected from the following examples can be appropriately combined within a range that does not contradict each other.

[0252] Modification 1

[0253] In the above-mentioned embodiment, the error distribution unit 223 uses the error diffusion process. Figure 7 The error diffusion data GK shown in FIG. 1 is used, but the present invention is not limited to this method. The error distribution unit 223 only needs to use error diffusion data that can distribute the error E in the Z-axis direction in addition to the error E in the XY plane in the error diffusion process. For example, the error distribution unit 223 can use Fig. 20 The error diffusion data GK-A shown can be used Fig.21 The error diffusion data shown in GK-B can also be used Fig. 22 The error diffusion data GK-C shown can also be used Fig.23 The error diffusion data GK-D shown, or you can also use Fig.24 The error diffusion data GK-E is shown.

[0254] Fig. 20 It is an explanatory diagram for explaining the error diffusion data GK-A.

[0255] like Fig. 20 As shown, the error diffusion data GK-A is, when the pixel Px(mx, my, mz) is the object pixel PxT, the pixels Px(mx+1, my, mz), pixel Px(mx, my+1, mz), pixel Px(mx, my, mz+1), pixel Px(mx+2, my, mz), pixel Px(mx, my+2, mz) and pixel Px(mx, my, mz+2) are designated as the data of the surrounding pixels PxS.

[0256] In addition, the error diffusion data GK-A is data for determining each distribution rate B in such a manner that the distribution rate B(1, 0, 0) is larger than the distribution rate B(0, 1, 0), the distribution rate B(0, 1, 0) is larger than the distribution rate B(1, 1, 0), the distribution rate B(2, 0, 0) is larger than the distribution rate B(0, 2, 0), and the distribution rate B(0, 2, 0) is larger than the distribution rate B(0, 0, 2).

[0257] Fig.21 It is an explanatory diagram for explaining the error diffusion data GK-B.

[0258] like Fig.21 As shown, the error diffusion data GK-B is, when the pixel Px(mx, my, mz) is the object pixel PxT, the pixels Px(mx+1, my, mz), pixel Px(mx, my+1, mz), pixel Px(mx, my, mz+1), pixel Px(mx+2, my, mz), pixel Px(mx, my+2, mz), pixel Px(mx, my, mz+2), pixel Px(mx+1, my+1, mz), pixel Px(mx, my+1, mz+1) and pixel Px(mx+1, my, mz+1) are designated as the data of the surrounding pixels PxS.

[0259] In addition, the error diffusion data GK-B is data for determining each distribution rate B in such a manner that the distribution rate B(1, 0, 0) is larger than the distribution rate B(0, 1, 0), the distribution rate B(0, 1, 0) is larger than the distribution rate B(1, 1, 0), the distribution rate B(2, 0, 0) is larger than the distribution rate B(0, 2, 0), the distribution rate B(0, 2, 0) is larger than the distribution rate B(1, 2, 0), the distribution rate B(1, 1, 0) is larger than the distribution rate B(1, 0, 1), and the distribution rate B(1, 0, 1) is larger than the distribution rate B(0, 1, 1).

[0260] Fig. 22 It is an explanatory diagram for explaining the error diffusion data GK-C.

[0261] like Fig. 22As shown, the error diffusion data GK-C is, when the pixel Px(mx, my, mz) is the object pixel PxT, the pixels Px(mx+1, my, mz), pixel Px(mx+1, my, mz+1), pixel Px(mx-1, my+1, mz), pixel Px(mx-1, my+1, mz+1), pixel Px(mx, my, mz+1), pixel Px(mx, my+1, mz), pixel Px(mx, my+1, mz+1), pixel Px(mx+1, my+1, mz) and pixel Px(mx+1, my+1, mz+1) are designated as the data of the surrounding pixels PxS.

[0262] In addition, the error diffusion data GK-C is data for determining each distribution rate B in such a manner that the distribution rate B(1,0,0) is larger than the distribution rate B(0,1,0), the distribution rate B(0,1,0) is larger than the distribution rate B(0,0,1), the distribution rate B(0,0,1) is larger than the distribution rate B(1,1,0), the distribution rate B(1,1,0) is larger than the distribution rate B(0,1,1), the distribution rate B(0,1,1) is larger than the distribution rate B(1,0,1), the distribution rate B(-1,1,0) and the distribution rate B(1,1,1), and the distribution rate B(1,0,1), the distribution rate B(-1,1,0) and the distribution rate B(1,1,1) are larger than the distribution rate B(-1,1,1).

[0263] Fig.23 It is an explanatory diagram for explaining the error diffusion data GK-D.

[0264] like Fig.23 As shown, the error diffusion data GK-D is, when the pixel Px(mx,my,mz) is the object pixel PxT, the pixels Px(mx,my,mz+1), pixel Px(mx,my,mz+2), pixel Px(mx+1,my,mz), pixel Px(mx+1,my,mz+1), pixel Px(mx+2,my,mz), pixel Px(mx-1,my+1,mz), pixel Px(mx-1,my+1,mz+1), pixel Px(mx,my+1,mz), pixel Px(mx,my+1,mz+1), pixel Px(mx+1,my+1,mz), pixel Px(mx+1,my+1,mz+1) and pixel Px(mx,my+2,mz) are designated as data of the surrounding pixels PxS.

[0265] The error diffusion data GK-D is such that the distribution rate B(1,0,0) is larger than the distribution rate B(0,1,0), the distribution rate B(0,1,0) is larger than the distribution rate B(0,0,1), the distribution rate B(0,0,1) is larger than the distribution rate B(2,0,0), the distribution rate B(2,0,0) is larger than the distribution rate B(0,2,0), and the distribution rate B(0,2,0) is larger than the distribution rate B(0,0,2). Data for determining each distribution rate B is obtained in such a way that the distribution rate B(0,0,2) is larger in comparison with the distribution rate B(1,0,1), the distribution rate B(0,1,1), and the distribution rate B(1,1,0), and the distribution rate B(1,0,1), the distribution rate B(0,1,1), and the distribution rate B(1,1,0) are larger in comparison with the distribution rate B(-1,1,0), the distribution rate B(-1,1,1), and the distribution rate B(1,1,1).

[0266] Fig.24 It is an explanatory diagram for explaining the error diffusion data GK-E.

[0267] like Fig.24 As shown, the error diffusion data GK-E is, when the pixel Px(mx, my, mz) is the object pixel PxT, the pixel Px(mx+1, my, mz), the pixel Px(mx+1, my+1, mz), the pixel Px(mx, my+1, mz), the pixel Px(mx-1, my+1, mz), the pixel Px(mx-1, my-1, mz+1), the pixel Px(mx, my-1, mz+ 1), pixel Px(mx+1, my-1, mz+1), pixel Px(mx-1, my, mz+1), pixel Px(mx, my, mz+1), pixel Px(mx+1, my, mz+1), pixel Px(mx-1, my+1, mz+1), pixel Px(mx, my+1, mz+1) and pixel Px(mx+1, my+1, mz+1) are designated as data of surrounding pixels PxS.

[0268] In addition, the error diffusion data GK-E is such that the distribution rate B(1,0,0) is larger than the distribution rate B(0,1,0), the distribution rate B(0,1,0) is larger than the distribution rate B(0,0,1), the distribution rate B(0,0,1) is larger than the distribution rate B(1,1,0), the distribution rate B(1,1,0) is larger than the distribution rate B(-1,1,0), the distribution rate B(-1,1,0) is larger than the distribution rate B(-1,0,1), and the distribution rate B(1 Data for determining each allocation rate B is made in a manner that makes allocation rate B(-1, 0, 1) larger than allocation rate B(0, -1, 1) and allocation rate B(0, 1, 1); and allocation rate B(0, -1, 1) and allocation rate B(0, 1, 1) larger than allocation rate B(-1, -1, 1), allocation rate B(1, -1, 1), allocation rate B(-1, 1, 1) and allocation rate B(1, 1, 1) larger than allocation rate B(1, 1, 1).

[0269] As described above, according to this modification, the error diffusion data GK-A, the error diffusion data GK-B, the error diffusion data GK-C, the error diffusion data GK-D, or the error diffusion data GK-E is used in the error diffusion process. The error diffusion data GK-A, the error diffusion data GK-B, the error diffusion data GK-C, the error diffusion data GK-D, and the error diffusion data GK-E are all error diffusion data for implementing the distribution of the error E in the Z-axis direction in addition to the distribution of the error E in the XY plane in the error diffusion process. Therefore, according to this modification, in the surface SF of the object Obj, in addition to the plane parallel to the XY plane, the dispersion of the arrangement of the points can be improved on the plane parallel to the XZ plane and the plane parallel to the YZ plane.

[0270] As described above, the terminal device 1 involved in the present variant example is characterized in that the error distribution unit 223 distributes the error E(mx, my, mz) caused by quantization of the grayscale value Gg(mx, my, mz) corresponding to the pixel Px(mx, my, mz) at a distribution rate B(2, 0, 0) to the pixel Px(mx+2, my, mz) located in the +X direction of the pixel Px(mx+1, my, mz) at a distribution rate B(0, 2, 0) to the pixel Px(mx, my+2, mz) located in the +Y direction of the pixel Px(mx, my+1, mz) at a distribution rate B(0, 0, 2) and to the pixel Px(mx, my, mz+2) located in the +Z direction of the pixel Px(mx, my, mz+1) at a distribution rate B(0, 0, 2).

[0271] Therefore, according to the present modification, even when the image G is formed on the surface SF of the target object Obj having a three-dimensional shape, the occurrence of graininess in the image G can be suppressed.

[0272] In addition, in this variant example, pixel Px(mx+2, my, mz) is an example of a “fourth pixel”, pixel Px(mx, my+2, mz) is an example of a “fifth pixel”, pixel Px(mx, my, mz+2) is an example of a “sixth pixel”, distribution rate B(2, 0, 0) is an example of a “fourth distribution rate”, distribution rate B(0, 2, 0) is an example of a “fifth distribution rate”, and distribution rate B(0, 0, 2) is an example of a “sixth distribution rate”.

[0273] In the terminal device 1 according to the present variation, the characteristics may be such that the allocation rate B(2,0,0) is larger than the allocation rate B(0,2,0) and the allocation rate B(0,0,2), and the allocation rate B(0,2,0) is larger than the allocation rate B(0,0,2).

[0274] Therefore, according to this modification, the uniformity of the distribution of the errors E for each of the M pixels Px in the image forming space SP can be improved compared to a method in which the distribution rate B(2,0,0) is equal to or lower than the distribution rate B(0,2,0). In addition, according to this modification, the uniformity of the distribution of the errors E for each of the M pixels Px in the image forming space SP can be improved compared to a method in which the distribution rate B(0,2,0) is equal to or lower than the distribution rate B(0,0,2).

[0275] In addition, in the terminal device 1 involved in the present variant example, the feature can also be set that the error distribution unit 223 distributes the error E(mx, my, mz) caused by quantization of the grayscale value Gg(mx, my, mz) corresponding to the pixel Px(mx, my, mz) at a distribution rate B(1, 1, 0) to the pixel Px(mx+1, my+1, mz) located in the +Y direction of the pixel Px(mx+1, my, mz) at a distribution rate B(1, 0, 1) to the pixel Px(mx+1, my, mz+1) located in the +Z direction of the pixel Px(mx+1, my, mz) at a distribution rate B(0, 1, 1) to the pixel Px(mx, my+1, mz+1) located in the +Z direction of the pixel Px(mx, my+1, mz+1).

[0276] Therefore, according to the present modification, even when the image G is formed on the surface SF of the target object Obj having a three-dimensional shape, the occurrence of graininess in the image G can be suppressed.

[0277] In addition, in this variant example, pixel Px(mx+1, my+1, mz) is an example of the “seventh pixel”, pixel Px(mx+1, my, mz+1) is an example of the “eighth pixel”, pixel Px(mx, my+1, mz+1) is an example of the “ninth pixel”, distribution rate B(1, 1, 0) is an example of the “seventh distribution rate”, distribution rate B(1, 0, 1) is an example of the “eighth distribution rate”, and distribution rate B(0, 1, 1) is an example of the “ninth distribution rate”.

[0278] In addition, in the terminal device 1 involved in this variation, the characteristics may be set such that the allocation rate B(1, 1, 0) is larger than the allocation rate B(1, 0, 1) and the allocation rate B(0, 1, 1), and the allocation rate B(1, 0, 1) is larger than the allocation rate B(0, 1, 1).

[0279] Modification 2

[0280] In the above-mentioned embodiment and modification 1, the error allocator 223 allocates the error E(mx, my, mz) corresponding to the pixel Px(mx, my, mz) as the target pixel PxT to the grayscale value Gg(mx+dx, my+dy, mz+dz) corresponding to the pixel Px(mx+dx, my+dy, mz+dz) as the surrounding pixel PxS in the error allocation process, but the present invention is not limited to this manner. The error allocator 223 may allocate the error E(mx, my, mz) corresponding to the pixel Px(mx, my, mz) as the target pixel PxT to the threshold value Th(mx+dx, my+dy, mz+dz) corresponding to the pixel Px(mx+dx, my+dy, mz+dz) as the surrounding pixel PxS in the error allocation process.

[0281] Fig.25 FIG. 1 is a flowchart showing an example of the operation of the recording system Sys when the recording system Sys according to the present modification performs display data generation processing. Fig.25 The flowchart shown is the same as that of FIG. 1 except that the process of step S30 described later is performed as the error allocation process instead of the process of step S17. Figure 6 The flowchart shown is the same.

[0282] like Fig.25 As shown, the display data generating unit 22 included in the recording system Sys according to the present modification example executes the above-described processes of steps S10 to S16 in the display data generating process.

[0283] Thereafter, as an error allocation process, the error allocation unit 223 according to the present modification uses the error diffusion data GK to allocate the error E(mx, my, mz) to one or more threshold values ​​Th corresponding to one or more surrounding pixels PxS located around the target pixel PxT (S30). Specifically, in the error allocation process of step S30, when there is a pixel Px(mx+dx, my+dy, mz+dz) as the surrounding pixel PxS, the error allocation unit 223 according to the present modification changes the threshold value Th(mx+dx, my+dy, mz+dz) corresponding to the pixel Px(mx+dx, my+dy, mz+dz) based on the following equation (8).

[0284] Th(mx+dx,my+dy,mz+dz)

[0285] =Th(mx+dx,my+dy,mz+dz)

[0286] +EB(dx,dy,dz)……Formula (8)

[0287] That is, in the error allocation processing of step S30, the error allocation unit 223 involved in this variant example changes the threshold value Th(mx+dx, my+dy, mz+dz) by adding the value obtained by multiplying the error E(mx, my, mz) by the allocation rate B(dx, dy, dz) to the threshold value Th(mx+dx, my+dy, mz+dz).

[0288] Thereafter, the display data generating unit 22 according to the present modification example executes the processes of steps S18 to S23 described above.

[0289] As described above, according to this modification, in the error distribution process, in addition to the distribution of the error E in the XY plane, the distribution of the error E in the Z-axis direction is also performed. Therefore, according to this modification, in the surface SF of the object Obj, in addition to the plane parallel to the XY plane, the dispersion of the point arrangement can be improved on the plane parallel to the XZ plane and the plane parallel to the YZ plane.

[0290] Modification 3

[0291] Although the grayscale value GI (mx, my, mz) set by the calculation processing unit 222 in the error diffusion process is exemplified as two values, namely, the maximum grayscale value GI-1 and the minimum grayscale value GI-0 in the above-mentioned embodiment and modified examples 1 and 2, the present invention is not limited to this embodiment. The grayscale value GI (mx, my, mz) set by the calculation processing unit 222 in the error diffusion process may be three or more values.

[0292] Fig.26 as well as Fig. 27 FIG. 1 is a flowchart showing an example of the operation of the recording system Sys when the recording system Sys according to the present modification performs display data generation processing. Fig.26 as well as Fig. 27 The flowchart shown is the same as that of FIG. 1 except that the process of step S400 including steps S40, S41, S42 and S44 is performed as the error diffusion process for one pixel instead of the process of step S100, the process of step S43 is performed instead of the process of step S14, and the process of step S45 is performed instead of the process of step S16. Figure 6 The flowchart shown is the same.

[0293] like Fig.26 As shown, the display data generating unit 22 according to the present modification example executes the above-described processes of steps S10 to S11 in the display data generating process.

[0294] Thereafter, the arithmetic processing unit 222 of the present modification example calculates the quotient GgA(mx, my, mz) and the remainder GgB(mx, my, mz) (S40) by dividing the grayscale value of the image Gf in the target pixel PxT represented by the image data GD, that is, the grayscale value Gg(mx, my, mz) by the reference value KK. In the present modification example, the reference value KK refers to an integer satisfying the following formula (9).

[0295] 0<KK≤{Gg-max-Gg-min}÷2...Equation (9)

[0296] In this modification, as an example, a case where the grayscale value Gg-min is “0” and the grayscale value Gg-max is “256” is assumed. In this modification, as an example, a case where the reference value KK is “64” is assumed.

[0297] Thereafter, the arithmetic processing unit 222 of this modification example determines whether the remainder GgB(mx, my, mz) is greater than or equal to the threshold value Th(mx, my, mz) (S41). In addition, in this modification example, it is assumed that the threshold value Th(mx, my, mz) satisfies the value of the following formula (10).

[0298] γ5*KK≤Th(mx,my,mz)≤γ6*KK...Equation (10)

[0299] Here, the value γ5 is, for example, a real number satisfying "0.3≤γ5≤0.5", and the value γ6 is, for example, a real number satisfying "0.5≤γ6≤0.7". More specifically, in this embodiment, as an example, a case where the threshold Th(mx, my, mz) is "32" is assumed. However, when the value obtained by subtracting the grayscale value Gg-min from the grayscale value Gg-max is not an integer multiple of the reference value KK, the threshold Th(mx, my, mz) may be an integer satisfying the following formula (11).

[0300] (1-γ7)*{KK*GgA(mx, my, mz)}

[0301] +γ7*{KK*(1+GgA(mx,my,mz))}

[0302] ≤Th(mx,my,mz)

[0303] ≤(1-γ8)*{KK*GgA(mx, my, mz)}

[0304] +γ8*{KK*(1+GgA(mx,my,mz))}......Formula (11)

[0305] Here, the value γ7 is a real number satisfying, for example, “0.3≤γ7≤0.5”, and the value γ8 is a real number satisfying, for example, “0.5≤γ8≤0.7”.

[0306] Then, when the result of the judgment in step S41 is affirmative, the operation processing unit 222 involved in this variant example sets the grayscale value GI(mx, my, mz) corresponding to the pixel Px(mx, my, mz) as the object pixel PxT to "1+GgA(mx, my, mz)" (S42).

[0307] Thereafter, the error allocator 223 of this modification example calculates the error E(mx, my, mz) based on the remainder GgB(mx, my, mz) and the reference value KK (S43). Specifically, in step S43, the error allocator 223 calculates the error E(mx, my, mz) based on the following formula (12).

[0308] E(mx,my,mz)=KK-GgB(mx,my,mz)

[0309] ……Formula (12)

[0310] On the other hand, when the result of the judgment in step S41 is negative, the operation processing unit 222 involved in this variant example sets the grayscale value GI(mx, my, mz) corresponding to the pixel Px(mx, my, mz) as the object pixel PxT to "GgA(mx, my, mz)" (S44).

[0311] Thereafter, the error allocator 223 according to the present modification sets a value obtained by multiplying the remainder GgB(mx, my, mz) by “−1” as the error E(mx, my, mz) ( S45 ).

[0312] Then, the display data generating unit 22 according to the present modification example executes the processes of steps S17 to S23 described above.

[0313] As described above, according to this variation, since the grayscale value GI (mx, my, mz) is greater than 3 values, compared with the case where the grayscale value GI (mx, my, mz) is 2 values, the image G formed on the surface SF of the object Obj can be made to be close to the image Gf.

[0314] Modification 4

[0315] In the above-described embodiment and modifications 1 to 3, the image Gf represented by the image data GD and the image G represented by the display data Img may include a plurality of colors.

[0316] In the present modification, it is assumed that the image Gf represented by the image data GD and the image G represented by the display data Img are represented by four colors: cyan, magenta, yellow, and black.

[0317] Moreover, in this modified example, it is assumed that the image data GD includes image data GD-Cy, image data GD-Mg, image data GD-Yl, and image data GD-Bk, wherein the image data GD-Cy represents the blue-green grayscale value that should be displayed by each pixel in the M pixels Px included in the image forming space SP in order to form the image Gf on the surface SF of the object Obj, and the image data GD-Mg represents the blue-green grayscale value that should be displayed by each pixel in the M pixels Px included in the image forming space SP in order to form the image Gf on the surface SF of the object Obj. The image data GD-Yl represents the magenta grayscale value displayed by each of the M pixels Px included in the image forming space SP in order to form the image Gf on the surface SF of the object Obj, and the image data GD-Bk represents the black grayscale value displayed by each of the M pixels Px included in the image forming space SP in order to form the image Gf on the surface SF of the object Obj.

[0318] In addition, in the present variant example, it is envisaged that the display data Img includes display data Img-Cy, display data Img-Mg, display data Img-Yl and display data Img-Bk, wherein the display data Img-Cy represents the cyan grayscale value that should be displayed by each of the M pixels Px included in the image forming space SP in order to form the image G on the surface SF of the object object Obj, the display data Img-Mg represents the magenta grayscale value that should be displayed by each of the M pixels Px included in the image forming space SP in order to form the image G on the surface SF of the object object Obj, the display data Img-Yl represents the yellow grayscale value that should be displayed by each of the M pixels Px included in the image forming space SP in order to form the image G on the surface SF of the object object Obj, and the display data Img-Bk represents the black grayscale value that should be displayed by each of the M pixels Px included in the image forming space SP in order to form the image G on the surface SF of the object object Obj.

[0319] In addition, in the present modification, the error diffusion data GK-Cy for performing error diffusion processing on the image data GD-Cy, the error diffusion data GK-Mg for performing error diffusion processing on the image data GD-Mg, the error diffusion data GK-Y1 for performing error diffusion processing on the image data GD-Y1, and the error diffusion data GK-Bk for performing error diffusion processing on the image data GD-Bk are stored in the storage unit 3 included in the recording system Sys according to the present modification. Here, the error diffusion data GK-Cy, the error diffusion data GK-Mg, the error diffusion data GK-Y1, and the error diffusion data GK-Bk may be the same data as any one of the error diffusion data GK, the error diffusion data GK-A, the error diffusion data GK-B, the error diffusion data GK-C, and the error diffusion data GK-D. The error diffusion data GK-Cy, the error diffusion data GK-Mg, the error diffusion data GK-Y1, and the error diffusion data GK-Bk may be data indicating distribution rates B that are equal to each other or may be data indicating distribution rates B that are different from each other.

[0320] In addition, in this modification, the operation processing unit 222 of this modification applies error diffusion processing to the image data GD-Cy, applies error diffusion processing to the image data GD-Mg, applies error diffusion processing to the image data GD-Y1, and applies error diffusion processing to the image data GD-Bk. In addition, the error distribution unit 223 of this modification applies error diffusion processing to the image data GD-Cy using the error diffusion data GK-Cy, applies error diffusion processing to the image data GD-Mg using the error diffusion data GK-Mg, applies error diffusion processing to the image data GD-Y1 using the error diffusion data GK-Y1, and applies error diffusion processing to the image data GD-Bk using the error diffusion data GK-Bk. Therefore, the display data generating unit 22 involved in this variant example generates display data Img-Cy based on the image data GD-Cy, generates display data Img-Mg based on the image data GD-Mg, generates display data Img-Yl based on the image data GD-Yl, and generates display data Img-Bk based on the image data GD-Bk.

[0321] As described above, according to this variation, since a plurality of error diffusion data are provided in such a manner that the plurality of colors of the image Gf represented by the image data GD and the image G represented by the display data Img correspond one to one, it is possible to suppress the occurrence of graininess in the image G when the image Gf represented by the image data GD and the image G represented by the display data Img are color images.

[0322] As described above, the terminal device 1 involved in the present variant is characterized in that the image data GD includes: image data GD-Cy, which represents the cyan gradation value that should be displayed by each of the M pixels Px in the image forming space SP when a cyan image is displayed in the image forming space SP; image data GD-Mg, which represents the magenta grayscale value that should be displayed by each of the M pixels Px in the image forming space SP when a magenta image is displayed in the image forming space SP, the display data generating unit 22 generates the display data Img-Cy by quantizing the cyan grayscale value represented by the image data GD-Cy, and generates the display data Img-Mg by quantizing the magenta grayscale value represented by the image data GD-Mg, and the error distribution unit 223 distributes the error E caused by the quantization of the cyan grayscale value corresponding to the pixel Px (mx, my, mz) at a distribution rate B (1, 0, 0). The pixel Px(mx+1, my, mz) located in the +X direction of the pixel Px(mx, my, mz) is allocated with an allocation rate B(0, 1, 0) to the pixel Px(mx, my+1, mz) located in the +Y direction of the pixel Px(mx, my, mz), and the pixel Px(mx, my, mz+1) located in the +Z direction of the pixel Px(mx, my, mz) is allocated with an allocation rate B(0, 0, 1), and the quantization of the grayscale value of magenta corresponding to the pixel Px(mx, my, mz) is performed. The error E brought about is distributed to the pixel Px(mx+1, my, mz) located in the +X direction of the pixel Px(mx, my, mz) at a distribution rate B(1, 0, 0), and to the pixel Px(mx, my+1, mz) located in the +Y direction of the pixel Px(mx, my, mz) at a distribution rate B(0, 1, 0), and to the pixel Px(mx, my, mz+1) located in the +Z direction of the pixel Px(mx, my, mz) at a distribution rate B(0, 0, 1).

[0323] Therefore, according to the present modification, when the color image G is printed on the surface SF of the target object Obj having a three-dimensional shape, the occurrence of graininess in the image G can be suppressed.

[0324] In addition, in the present variation, cyan is an example of the “first color”, magenta is an example of the “second color”, a cyan image is an example of the “first image”, a magenta image is an example of the “second image”, a cyan grayscale value is an example of the “first grayscale value”, a magenta grayscale value is an example of the “second grayscale value”, image data GD-Cy is an example of the “first image data”, image data GD-Mg is an example of the “second image data”, display data Img-Cy is an example of the “first display data”, and display data Img-Mg is an example of the “second display data”.

[0325] Modification 5

[0326] In the above-mentioned embodiment and variations 1 to 4, the value Mx, the value My, and the value Mz may be values ​​satisfying the following formula (13), or values ​​satisfying the following formula (14). In the following formulas (13) and (14), α is a natural number greater than or equal to 2.

[0327] Mx=My=Mz=α2...Equation (13)

[0328] Mx=My=Mz=2α……Equation (14)

[0329] Modification 6

[0330] In the above-described embodiment and modifications 1 to 5, the terminal control unit 2 and the storage unit 3 may be mounted on the recording device 5 .

[0331] Furthermore, in the above-described embodiment and Modifications 1 to 5, the terminal device 1 may include the recording control unit 6 , the head unit 7 , the ink supply unit 8 , and the robot arm 9 .

[0332] Modification 7

[0333] Although the robot arm 9 changes the position and posture of the head unit 7 in the image forming space SP in the above-mentioned embodiment and modified examples 1 to 6, the present invention is not limited to this method. It is also possible to set the robot arm 9 to be able to change the position and posture of the target object Obj in the image forming space SP. In this case, it is also possible to set the position and posture of the head unit 7 to be fixed in the image forming space SP.

[0334] <Variant 8>

[0335] In the above-mentioned embodiment and modified examples 1 to 7, when the pixel selection unit 221 determines that "mx=Mx" is satisfied in step S18 and the pixel selection unit 221 determines that "my=My" is not satisfied in step S20, the value mx is set to "1" and "1" is added to the value my in step S21, but the present invention is not limited to this manner. The pixel selection unit 221 may also set the value mx to "Mx" as it is in step S21 and add "1" to the value my. That is, the pixel to be subjected to the error diffusion process next to the pixel Px(Mx, my, mz) may be set to the pixel Px(Mx, my+1, mz) instead of the pixel Px(1, my+1, mz). However, in this case, in step S18 of the error diffusion process for the pixel Px(Mx, my+1, mz), the determination of whether "mx=Mx" is satisfied in the above-mentioned embodiment and modified examples 1 to 7 is changed to the determination of whether "mx=1" is satisfied. Furthermore, in step S19 of the error diffusion process for the pixel Px(Mx, my+1, mz), the addition of "1" to the value mx in the above-mentioned embodiment and variants 1 to 7 is changed to the addition of "-1" to the value mx. Furthermore, in the error diffusion process for the pixel Px(1, my+1, mz), the conditions of steps S18, S19, and S21 are restored to the original conditions. That is, the pixel to be subjected to error diffusion process next to the pixel Px(1, my+1, mz) is made to be the pixel Px(1, my+2, mz), and the next pixel is made to be the pixel Px(2, my+2, mz). Thereafter, the conditions of steps S18, S19, and S21 are switched alternately in the same manner.

[0336] According to the error diffusion process, when the error diffusion process is sequentially performed on the pixel column extending in the X-axis direction including the pixel Px (Mx, my, mz), the target pixels to be subjected to the error diffusion process are sequentially shifted in the +X direction, whereas, when the error diffusion process is sequentially performed on the pixel column extending in the X-axis direction including the pixel Px (Mx, my+1, mz), the target pixels to be subjected to the error diffusion process are sequentially shifted in the -X direction. Thereafter, the shift in the +X direction and the shift in the -X direction are alternately repeated.

[0337] In addition, although the conditions of step S18, step S19, and step S21 are alternately switched when "mx = Mx" or "mx = 1" is satisfied in step S18 in the above description, the conditions of step S18, step S19, and step S23 may be switched in the same manner. That is, when the pixel selection unit 221 determines that "mx = Mx" is satisfied in step S18, the pixel selection unit 221 determines that "my = My" is satisfied in step S20, and the pixel selection unit 221 determines that "mz = Mz" is not satisfied in step S22, in step S23, the value mx is set to the value (that is, either "Mx" or "1"), the value my is set to the value (that is, either "My" or "1"), and "1" is added to the value mz. In this case, the conditions of step S18 and step S19 may be switched in the same manner as described above. That is, if the condition of step S18 at this time is whether "mx = Mx" is satisfied, it is switched to whether "mx = 1" is satisfied, and conversely, if it is whether "mx = 1" is satisfied, it is switched to whether "mx = Mx" is satisfied. Similarly, if the condition of step S19 at this time is to add "1" to the value mx, it is switched to add "-1" to the value mx, and conversely, if it is to add "-1" to the value mx, it is switched to add "1" to the value mx.

[0338] In addition, it is preferable that when the condition of step S19 is switched, Figures 7 and 8 , Figure 20 to Figure 23 , Fig. 27 For example, in the error diffusion data, if dx=1, it is preferably switched to dx=-1, if dx=-2, it is preferably switched to dx=2, and if dx=0, it is preferably maintained as it is.

[0339] Explanation of symbols

[0340] 1…terminal device; 2…terminal control unit; 3…storage unit; 5…recording device; 6…recording control unit; 7…head unit; 8…ink supply unit; 9…robot arm; 21…image data acquisition unit; 22…display data generation unit; 61…head control unit; 62…arm control unit; 71…drive signal supply unit; 72…recording head; 221…pixel selection unit; 222…arithmetic processing unit; 223…error distribution unit; D…ejection unit; Sys…recording system.

Claims

1. An image processing device, characterized in that: have: an acquisition unit that acquires image data representing a grayscale value of an image that should be displayed by each of a plurality of pixels in the three-dimensional space when the image is displayed in the three-dimensional space; a generating unit that generates display data by quantizing the grayscale value represented by the image data, The generating unit comprises: a selection unit that selects one pixel from the plurality of pixels; a distribution unit that distributes an error caused by quantization of a grayscale value corresponding to the one pixel to a first pixel located in a first direction of the one pixel at a first distribution rate, distributes an error to a second pixel located in a second direction of the one pixel at a second distribution rate, and distributes an error to a third pixel located in a third direction of the one pixel at a third distribution rate, The second direction is a direction intersecting the first direction, The third direction is a direction different from the extending direction of the plane defined by the first direction and the second direction, When any one of the plurality of pixels in the three-dimensional space exists in the first direction of the one pixel, the selection unit selects other pixels located in the first direction of the one pixel after selecting the one pixel, The first distribution ratio is larger than the second distribution ratio and the third distribution ratio.

2. The image processing device according to claim 1, wherein: The plurality of pixels in the three-dimensional space include a plurality of pixel columns extending in the first direction, In the case where there is no pixel in the plurality of pixels in the three-dimensional space in the first direction of the one pixel, After selecting the one pixel, the selection unit selects other pixels from other pixel columns located in the second direction of a pixel column including the one pixel.

3. The image processing device according to claim 2, wherein: The plurality of pixels in the three-dimensional space include a plurality of pixel planes parallel to a plane defined by the first direction and the second direction. In the case where there is no pixel in the plurality of pixels in the three-dimensional space in the first direction of the one pixel and there is no pixel column in the plurality of pixel columns in the three-dimensional space in the second direction of a pixel column including the one pixel, After selecting the one pixel, the selection unit selects other pixels from other pixel planes located in the third direction on a pixel plane including the one pixel.

4. The image processing device according to claim 1, wherein: The second distribution ratio is larger than the third distribution ratio.

5. The image processing device according to claim 1, wherein: The first pixel is a pixel adjacent to the one pixel in a first direction of the one pixel, The second pixel is a pixel adjacent to the one pixel in a second direction of the one pixel, The third pixel is a pixel adjacent to the one pixel in the third direction of the one pixel.

6. The image processing device according to claim 5, characterized in that: The distribution unit distributes the error caused by quantization of the grayscale value corresponding to the one pixel to the fourth pixel adjacent to the first pixel in the first direction of the first pixel at a fourth distribution rate, and to the fifth pixel adjacent to the second pixel in the second direction of the second pixel at a fifth distribution rate, and to the sixth pixel adjacent to the third pixel in the third direction of the third pixel at a sixth distribution rate.

7. The image processing device according to claim 6, wherein: The fourth distribution ratio is larger than the fifth distribution ratio and the sixth distribution ratio. The fifth distribution ratio is larger than the sixth distribution ratio.

8. The image processing device according to any one of claims 5 to 7, characterized in that: The distribution unit distributes the error caused by quantization of the grayscale value corresponding to the one pixel to the seventh pixel adjacent to the first pixel in the second direction of the first pixel at a seventh distribution rate, to the eighth pixel adjacent to the first pixel in the third direction of the first pixel at an eighth distribution rate, and to the ninth pixel adjacent to the second pixel in the third direction of the second pixel at a ninth distribution rate.

9. The image processing device according to claim 8, wherein: The seventh distribution rate is larger than the eighth distribution rate and the ninth distribution rate. The eighth distribution ratio is larger than the ninth distribution ratio.

10. The image processing device according to claim 1, wherein: The first pixel is located at the same position as the one pixel in the second direction and the third direction, The second pixel is located at the same position as the one pixel in the first direction and the third direction, The third pixel is located at the same position as the one pixel in the first direction and the second direction.

11. The image processing device according to claim 1, wherein: The first direction is a direction orthogonal to the second direction and the third direction, The second direction is a direction orthogonal to the third direction.

12. The image processing device according to claim 1, wherein: A head unit is provided for ejecting liquid based on the display data.

13. The image processing device according to claim 1, wherein: The generating unit supplies the display data to a recording device, and the recording device includes a head unit that discharges liquid based on the display data.

14. The image processing device according to claim 1, wherein: The image data includes: first image data indicating a first grayscale value, the first grayscale value being a grayscale value of a first image that should be displayed by each of a plurality of pixels in the three-dimensional space when a first image of a first color is displayed in the three-dimensional space; second image data, which represents a second grayscale value, the second grayscale value being a grayscale value of a second image that should be displayed by each of a plurality of pixels in the three-dimensional space when a second image of a second color is displayed in the three-dimensional space, The generating unit generates first display data by quantizing a first grayscale value represented by the first image data, and generates second display data by quantizing a second grayscale value represented by the second image data, The distribution unit distributes the error caused by quantization of the first grayscale value corresponding to the one pixel to a first pixel located in a first direction of the one pixel at a first distribution rate, distributes the error to a second pixel located in a second direction of the one pixel at a second distribution rate, and distributes the error to a third pixel located in a third direction of the one pixel at a third distribution rate. The error caused by quantization of the second grayscale value corresponding to the one pixel is distributed to the first pixel at a tenth distribution rate, to the second pixel at an eleventh distribution rate, and to the third pixel at a twelfth distribution rate.

15. A recording device, characterized in that: It forms an image of a three-dimensional object and has: a head unit, which ejects liquid; a control unit that controls the ejection of liquid from the head unit so as to form the image on the target object by using a plurality of points whose arrangement is determined by an error diffusion method and formed by the liquid ejected from the head unit, The control unit controls the ejection of liquid from the head unit so that, when the target object has a first surface, distribution of multiple points on the first surface has a frequency characteristic in a spatial frequency domain in which high-frequency components higher than a predetermined frequency are more than low-frequency components lower than the predetermined frequency, and so that, when the target object has a second surface which is not parallel to the first surface, distribution of multiple points on the second surface has a frequency characteristic in a spatial frequency domain in which high-frequency components higher than a predetermined frequency are more than low-frequency components lower than the predetermined frequency.

16. The recording device according to claim 15, characterized in that The distribution of the plurality of points on the first surface has a frequency characteristic different from a white noise characteristic in the spatial frequency domain, The distribution of the plurality of points on the second plane has a frequency characteristic different from a white noise characteristic in a spatial frequency domain.

17. The recording device according to claim 15 or 16, characterized in that The distribution of the plurality of points on the first surface has a blue noise characteristic in the spatial frequency domain, The distribution of the plurality of points on the second surface has a blue noise characteristic in the spatial frequency domain.

18. An image processing method, characterized in that: have: an acquisition step of acquiring image data representing a grayscale value of an image that should be displayed by each of a plurality of pixels in the three-dimensional space when the image is displayed in the three-dimensional space; a generating step of quantizing the grayscale value represented by the image data to generate display data, The generation process comprises: A selecting step of selecting a pixel from the plurality of pixels; a distribution step of distributing an error caused by quantization of a grayscale value corresponding to the one pixel to a first pixel located in a first direction of the one pixel at a first distribution rate, distributing an error to a second pixel located in a second direction of the one pixel at a second distribution rate, and distributing an error to a third pixel located in a third direction of the one pixel at a third distribution rate, The second direction is a direction intersecting the first direction, The third direction is a direction different from the extending direction of the plane defined by the first direction and the second direction, In the selection process, when any one of the plurality of pixels in the three-dimensional space exists in the first direction of the one pixel, after the one pixel is selected, other pixels located in the first direction of the one pixel are selected. The first distribution ratio is larger than the second distribution ratio and the third distribution ratio.

19. A storage medium, characterized in that: The computer stores a program for causing the computer to function as the following components: an acquisition unit that acquires image data representing a grayscale value of an image that should be displayed by each of a plurality of pixels in the three-dimensional space when the image is displayed in the three-dimensional space; a generating unit that generates display data by quantizing the grayscale value represented by the image data, The generating unit functions as a selecting unit and an allocating unit, the selecting unit selecting one pixel from the plurality of pixels, the allocating unit allocating an error caused by quantization of a grayscale value corresponding to the one pixel to a first pixel located in a first direction of the one pixel at a first allocation rate, and to a second pixel located in a second direction of the one pixel at a second allocation rate, and to a third pixel located in a third direction of the one pixel at a third allocation rate, The second direction is a direction intersecting the first direction, The third direction is a direction different from the extending direction of the plane defined by the first direction and the second direction, When any one of the plurality of pixels in the three-dimensional space exists in the first direction of the one pixel, the selection unit selects other pixels located in the first direction of the one pixel after selecting the one pixel, The first distribution ratio is larger than the second distribution ratio and the third distribution ratio.

Images