Method for generating dot data, and printing apparatus

Abstract

This design suppresses deterioration of diagonal edges in two diagonal directions while also preventing a decline in print quality due to ink bleeding. [Solution] The determination area includes a cross-shaped area that includes the pixel of interest and its neighbors in the first and second directions, and corner pixels at the four corners. The corner pixels at the four corners include a first corner pixel and a second corner pixel that is not diagonally opposite the first corner pixel in the determination area. In the detection step, if the first condition is met in the determination area, where the cross-shaped area is in the dark area, the first corner pixel is in the surrounding area, and the three corner pixels excluding the first corner pixel are in the dark area, the pixel of interest is detected as the inner part of the processing target. If the second condition is met in the determination area, where the cross-shaped area is in the dark area, the second corner pixel is in the surrounding area, and the three corner pixels excluding the second corner pixel are in the dark area, the pixel of interest is detected as the inner part of the processing target.

Description

Technical Field

[0001] The present invention relates to a dot data generation method for generating dot data indicating the positions of dots formed by ink from a print head, and a printing apparatus.

Background Art

[0002] As a printing apparatus, an inkjet printer that forms a printed image by ejecting ink droplets from a print head is known. Since the ink droplets are liquid, the print quality may deteriorate due to bleeding of the edges of regions darker than the surroundings, such as characters and barcodes, on the printing medium. To prevent such a deterioration in print quality, it is conceivable to suppress the ejection of ink over the entire edge of the dark region. In the method for generating ejection position data disclosed in Patent Document 1, a process is performed to change the pixel values from ejection values to non-ejection values by one pixel each on both sides for a line having a width of three or more pixels.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, when changing the pixel values from ejection values to non-ejection values over the entire edge for a thin diagonal line such as the scraping part of a small character, the diagonal line becomes too thin and the deterioration of the object including the diagonal line becomes conspicuous. In the above-described method for generating ejection position data, the deterioration of the diagonal line is not taken into consideration.

Means for Solving the Problems

[0005] The present invention is a dot data generation method that generates dot data indicating the position of dots formed by ink from a print head, An image having a plurality of pixels arranged in a first direction and a second direction perpendicular to the first direction includes a surrounding region and a denser region than the surrounding region. The aforementioned dot data generation method is: A detection step in which, if a rectangular determination area centered on a pixel of interest included in at least a portion of the detection target area of ​​the aforementioned image satisfies a predetermined edge-inside condition including the surrounding area and the dense area, the pixel of interest is detected as the inner part of the processing target, The process includes a generation step of generating dot data from the image such that the amount of ink ejected from the print head to the inner part of the object to be processed is reduced, The determination region includes a cross-shaped region within the determination region that includes the pixel of interest and the pixels adjacent to the pixel of interest in the first and second directions, and corner pixels at the four corners of the determination region. The corner pixels at the four corners include a first corner pixel and a second corner pixel that is not diagonally opposite the first corner pixel in the determination area. In the detection step, In the determination region, if the first condition is met as the inner edge condition, where the cross region is in the dark region, the first corner pixel is in the surrounding region, and the three corner pixels excluding the first corner pixel are in the dark region, then the pixel of interest is detected as the inner part of the processing target. In the determination area, if the second condition is met as the inner edge condition, where the cross region is in the dark region, the second corner pixel is in the surrounding region, and the three corner pixels excluding the second corner pixel are in the dark region, then the pixel of interest is detected as the inner part of the processing target.

[0006] Furthermore, the present invention relates to a printing apparatus that forms a printed image on a printing medium using ink, A print head capable of ejecting the aforementioned ink, The system includes a control unit that controls the ejection of ink from the print head to the printing medium so that dots constituting the printed image are formed on the printing medium, An image having a plurality of pixels arranged in a first direction and a second direction perpendicular to the first direction includes a surrounding region and a denser region than the surrounding region. The control unit, A detection process in which, if a rectangular determination area centered on a pixel of interest included in at least a portion of the detection target area of ​​the aforementioned image satisfies a predetermined edge-inside condition including the surrounding area and the dense area, the pixel of interest is detected as the inner part of the processing target, Discharge control processing is performed to control the discharge of the ink from the print head to the printing medium so that the amount of ink discharged to the inner part of the object to be processed is reduced. The determination region includes a cross-shaped region within the determination region that includes the pixel of interest and the pixels adjacent to the pixel of interest in the first and second directions, and corner pixels at the four corners of the determination region. The corner pixels at the four corners include a first corner pixel and a second corner pixel that is not diagonally opposite the first corner pixel in the determination area. In the detection process, the control unit, In the determination region, if the first condition is met as the inner edge condition, where the cross region is in the dark region, the first corner pixel is in the surrounding region, and the three corner pixels excluding the first corner pixel are in the dark region, then the pixel of interest is detected as the inner part of the processing target. In the determination area, if the second condition is met as the inner edge condition, where the cross region is in the dark region, the second corner pixel is in the surrounding region, and the three corner pixels excluding the second corner pixel are in the dark region, then the pixel of interest is detected as the inner part of the processing target. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic diagram showing an example of the configuration of a printing device. [Figure 2] A schematic diagram showing an example of the nozzle surface of a print head. [Figure 3] A flowchart schematically showing an example of printing control processing. [Figure 4] A diagram schematically showing an example of generating a corrected image with a reduced ink amount in the inner part of the processing target from an input image. [Figure 5] A diagram schematically showing an example of combining individual reference patterns. [Figure 6] A diagram schematically showing an example of forming a printed image from dot data. [Figure 7] A diagram schematically showing another example of generating a corrected image with a reduced ink amount in the inner part of the processing target from an input image. [Figure 8] A diagram schematically showing an example of forming a printed image with a reduced ink amount in the edge part of the processing target from an input image. [Figure 9] A diagram schematically showing another example of forming a printed image from dot data. [Figure 10] FIG. 10A is a diagram schematically showing an example of an inner ink amount specification screen, FIG. 10B is a diagram schematically showing an example of a density region specification screen, and FIG. 10C is a diagram schematically showing an example of an edge depth specification screen. [Figure 11] A diagram schematically showing an example of generating a corrected image by deepening the inner part of the processing target. [Figure 12] FIG. 12A is a diagram schematically showing an example of an object specification screen, and FIG. 12B is a diagram schematically showing an example of a detection target region included in an image. [Figure 13] A diagram schematically showing a comparative example of forming a printed image from an input image.

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described. Of course, the following embodiments are merely illustrative of the present invention, and not all of the features shown in the embodiments are essential to the solution means of the invention.

[0009] (1) Outline of the aspects included in the present invention: First, an overview of the embodiments included in the present invention will be described with reference to the examples shown in Figures 1 to 13. Note that the figures in this application are schematic examples, and the scale of each part may differ from reality in order to make each part recognizable. The magnification in each direction shown in these figures may also differ, and the figures may not be consistent. Of course, the elements of this embodiment are not limited to the specific examples indicated by the reference numerals. In "Overview of Embodiments Included in the Present Invention," the text in parentheses indicates supplementary explanation of the preceding word. Furthermore, in this application, the numerical range "Min~Max" means a value greater than or equal to the minimum value Min and less than or equal to the maximum value Max.

[0010] [Aspect 1] As illustrated in Figures 2-7, a dot data generation method according to one embodiment is a dot data generation method that generates dot data DA2 indicating the position of dots 38 formed by ink 36 from a print head 30, and includes the following steps. The image IM1 having a plurality of pixels PX0 arranged in a first direction D1 and a second direction D2 perpendicular to the first direction D1 includes a surrounding region AR2 and a denser region AR3 that is darker than the surrounding region AR2. (a1) Detection step ST1 in which, if a rectangular determination area AD0 centered on a pixel of interest PX1 included in at least a part of the detection target area AR1 of the image IM1 satisfies a predetermined edge inside condition (for example, the pixel arrangement of the reference pattern P0) which includes the surrounding area AR2 and the dense area AR3, the pixel of interest PX1 is detected as the inner part F1 to be processed. (a2) Generation step ST2, which generates the dot data DA2 from the image IM1 such that the amount of ink 36 ejected from the print head 30 to the inner part F1 of the processing target is reduced, including 0. The determination region AD0 includes a cross-shaped region PX10 in the determination region AD0 that includes the target pixel PX1 and the adjacent pixels of the target pixel PX1 in the first direction D1 and the second direction D2, and corner pixels PX3 at the four corners of the determination region AD0. The corner pixels PX3 at the four corners include a first corner pixel PX31 and a second corner pixel PX32 that is not diagonally opposite the first corner pixel PX31 in the determination region AD0. In the detection step ST1, if the first condition (for example, the pixel arrangement of reference pattern P1) is met in the determination region AD0, where the cross-shaped region PX10 is in the dense region AR3, the first corner pixel PX31 is in the surrounding region AR2, and the three corner pixels PX3 excluding the first corner pixel PX31 are in the dense region AR3, then the target pixel PX1 is detected as the inner part F1 of the processing target. In the detection step ST1, if the second condition (for example, the pixel arrangement of the reference pattern P2) is met in the determination area AD0 such that the cross-shaped area PX10 is in the dense area AR3, the second corner pixel PX32 is in the surrounding area AR2, and the three corner pixels PX3 excluding the second corner pixel PX32 are in the dense area AR3, then the pixel of interest PX1 is detected as the inner part F1 of the processing target.

[0011] As a result, the amount of ink 36 ejected to the slightly inward portion of the edge along either of the two diagonal directions is reduced. This makes it possible to suppress the deterioration of print quality due to ink bleeding while avoiding the inconvenience of diagonal edges of objects, such as thin diagonal lines including the sweeping parts of small characters, becoming too thin. Therefore, the above embodiment can provide a dot data generation method that can suppress the deterioration of diagonal edges in two diagonal directions while suppressing the deterioration of print quality due to ink bleeding. Furthermore, the "generation step ST2 that generates the dot data DA2 from the image IM1 such that the amount of ink 36 ejected to the inner part F1 of the processing target is reduced, including 0" means that the dot data DA2 is generated such that the amount of ink 36 ejected to the inner part F1 of the processing target becomes 0, or is reduced within a range greater than 0. The phrase "reduced, including 0" that appears later can be interpreted in the same way.

[0012] Various examples can be considered for the embodiments described above. The size of the dots may be changeable. Therefore, the dot data may be binary data representing the presence or absence of dots, or multi-valued data with three or more values ​​representing the state of dot formation. The area to be detected can be the entire image or a portion of the image. A rectangular judgment area includes a square judgment area. A reduction in the amount of ink ejected to the inside of the processing target includes cases where no ink is ejected to the inside of the processing target. In this application, "first," "second," ... are terms used to identify each component included in a group of similar components, and do not imply any order. Of course, the above-mentioned supplementary statement also applies in the following embodiments.

[0013] [Aspect 2] As illustrated in Figures 3 and 8, in the detection step ST1, at least one of the edges E0 present in the detection target area AR1, namely the first edge portion E11 located on one side of the dense area AR3 in the first direction D1 and the second edge portion E12 located on one side of the dense area AR3 in the second direction D2, may be detected as the edge portion E1 to be processed. In the generation step ST2, the dot data DA2 may be generated from the image IM1 such that the amount of ink 36 ejected from the print head 30 to the edge portion E1 to be processed is reduced, including 0. As a result, the amount of ink 36 ejected to at least one of the first edge portion E11 located on one side of the dense area AR3 in the first direction D1, and the second edge portion E12 located on one side of the dense area AR3 in the second direction D2, is reduced, rather than the entire edge E0 present in the detection target area AR1. This makes it possible to suppress the deterioration of print quality due to ink bleeding while avoiding the inconvenience of objects such as barcodes and fine characters becoming too thin. Therefore, the above embodiment can provide a dot data generation method that can suppress the deterioration of fine lines due to the absence of ink ejection across the entire edge, while also suppressing the deterioration of print quality due to ink bleeding.

[0014] Various examples can be considered for the embodiments described above. For example, if the first direction is oriented left or right, the first edge does not mean that it exists on both the left and right sides of the dense region, but rather that it exists on either the left or right side of the dense region. If the second direction is oriented up or down, the second edge does not mean that it exists on both the top and bottom sides of the dense region, but rather that it exists on either the top or bottom side of the dense region. Of course, the first direction may also be oriented up or down, and the second direction may also be oriented left or right. A reduction in the amount of ink ejected to the processing edge includes cases where no ink is ejected to the processing edge. Of course, the above-mentioned supplementary statement also applies in the following embodiments.

[0015] [Aspect 3] As illustrated in Figures 8 and 9, in the generation step ST2, the amount of ink 36 discharged from the print head 30 to the processing target edge portion E1 may be less than the amount of ink 36 discharged from the print head 30 to the processing target inner portion F1. Since the amount of ink discharged to the processing target edge E1 is less than the amount of ink discharged to the processing target inner part F1, the bleeding of ink 36 that spreads from the edge is suppressed. Therefore, the above embodiment can further suppress the deterioration of print quality of objects such as barcodes and fine characters due to ink bleeding.

[0016] [Aspect 4] As illustrated in Figure 10B, this dot data generation method may further include the following steps. (a3) A color specification step ST4 that accepts the specification of an option 240 to be applied to the dark area AR3 from among a plurality of options 240 including a predetermined color (e.g., "black only" option 241) and a predetermined color range (e.g., "other than white" option 242). In the detection step ST1, if a predetermined color (241) is specified, the pixel of interest PX1 may be detected as the inner part F1 of the processing target if the distribution of the dark area AR3 and the surrounding area AR2, which are of the predetermined color (241), in the determination area AD0 satisfies the inside edge condition (P0). Alternatively, in the detection step ST1, if a predetermined color range (242) is specified, the pixel of interest PX1 may be detected as the inner part F1 of the processing target if the distribution of the dark area AR3 and the surrounding area AR2, which are in the predetermined color range (242), in the determination area AD0 satisfies the inside edge condition (P0).

[0017] If an object such as a thin diagonal line is of a predetermined color (241) and that predetermined color (241) is specified, a high-quality printed image IM5 can be obtained for objects of that predetermined color (241) by reducing the amount of ink in the inner part F1 of the processing target. If an object is included in a predetermined color range (242) and that predetermined color range (242) is specified, a high-quality printed image IM5 can be obtained for objects within that predetermined color range (242) by reducing the amount of ink in the inner part F1 of the processing target. Therefore, the above embodiment can obtain a high-quality printed image depending on the color of an object such as a thin diagonal line.

[0018] [Aspect 5] As illustrated in Figures 10C and 11, this dot data generation method may further include the following steps. (a4) Edge depth specification step ST5 that accepts the specification of the depth of the inner part F1 to be processed. Furthermore, the depth of the inner part F1 being processed refers to the extent to which it extends from edge E0, located at the boundary between the concentrated region AR3 and the surrounding region AR2, into the interior of the concentrated region AR3. In the detection step ST1, the inner portion F1 of the object to be processed may be detected to the specified depth.

[0019] In the above case, the depth of the inner part F1 of the detected processing target can be adjusted to the user's intent. Therefore, the above embodiment can improve the image quality of the printed image according to the user's intent.

[0020] [Aspect 6] As illustrated in Figures 12A and 12B, this dot data generation method may further include the following steps. (a5) Object specification step ST6, which specifies an object included in the image IM1 (for example, item 281, "text and lines"). In the detection step ST1, the area of ​​the specified object (281) (for example, the character area AR1c and the line area AR1b) may be used as the detection target area AR1 to detect the inner part F1 to be processed.

[0021] In the above case, the detection target area AR1 can be adjusted to the user's intent. Therefore, the above embodiment can improve the image quality of the printed image according to the user's intent.

[0022] [Aspect 7] Incidentally, as illustrated in Figures 1 and 2, a printing apparatus 1 according to one embodiment is a printing apparatus 1 that forms a print image IM5 on a printing medium ME0 using ink 36, and comprises a print head 30 and a control unit U1. The print head 30 is capable of ejecting the ink 36. The control unit U1 controls the ejection of the ink 36 from the print head 30 to the printing medium ME0 so that dots 38 constituting the print image IM5 are formed on the printing medium ME0. The control unit U1 performs the following processing as illustrated in Figures 3 to 7, etc. (b1) A detection process (for example, steps S102 to S104 in Figure 3) in which, if a rectangular determination region AD0 centered on a pixel of interest PX1 included in at least a part of the detection target region AR1 of the image IM1 satisfies a predetermined edge inside condition (P0) which includes the surrounding region AR2 and the dense region AR3, the pixel of interest PX1 is detected as the processing target inside part F1. (b) Discharge control processing (for example, steps S106 to S114 in Figure 3) that controls the discharge of the ink 36 from the print head 30 to the printing medium ME0 so that the amount of ink 36 discharged to the inner part F1 of the processing target is reduced, including 0.

[0023] In the detection process described above, if the control unit U1 satisfies the first condition (P1) in the determination region AD0 where the cross-shaped region PX10 is in the dark region AR3, the first corner pixel PX31 is in the surrounding region AR2, and the three corner pixels PX3 excluding the first corner pixel PX31 are in the dark region AR3, then the control unit U1 detects the pixel of interest PX1 as the inner part of the processing target F1. Furthermore, in the detection process described above, if the control unit U1 satisfies the second condition (P2) in the determination region AD0 where the cross-shaped region PX10 is in the dark region AR3, the second corner pixel PX32 is in the surrounding region AR2, and the three corner pixels PX3 excluding the second corner pixel PX32 are in the dark region AR3, then the control unit U1 detects the pixel of interest PX1 as the inner part of the processing target F1.

[0024] The above embodiment provides a printing apparatus that can suppress deterioration of diagonally oriented edges in two diagonal directions while suppressing a decrease in print quality due to ink bleeding. Furthermore, the control unit U1 may perform at least a part of the color specification process corresponding to the color specification process ST4, the edge depth specification process corresponding to the edge depth specification process ST5, and the object specification process corresponding to the object specification process ST6.

[0025] Furthermore, the above-described embodiments are applicable to a printing method including the dot data generation method described above, a printing system including the printing apparatus described above, a control method for the printing apparatus described above, a control program for the printing apparatus described above, a computer-readable non-temporary medium on which the control program is recorded, and so on. In addition, the aforementioned printing apparatus may be composed of multiple distributed parts.

[0026] (2) Specific examples of printing devices: Figure 1 schematically illustrates the configuration of the printing device 1. In this specific example, the printing device 1 is assumed to be the printer 2 itself, but the printing device 1 may also be a combination of the printer 2 and a host device HO1. The host device HO1 shown in Figure 1 is equipped with a display device DU1. The printer 2 shown in Figure 1 is an inkjet printer that ejects ink 36 as ink droplets 37 from a print head 30. The printer 2 may also be a line printer in which the printing medium ME0 moves in the feed direction D3 without the print head 30 moving, or a serial printer, etc., and the printing device 1 may include additional elements not shown in Figure 1. Figure 2 schematically illustrates the nozzle surface 30a of the print head 30.

[0027] Printer 2 forms a print image IM5 on the printing medium ME0 using ink 36 ejected from the print head 30. The printer 2 shown in Figure 1 includes a controller 10, a semiconductor memory RAM (Random Access Memory) 21, a communication I / F (interface) 22, a storage unit 23, an operation panel 24, a print head 30, a drive unit 50, etc. The controller 10 and the drive unit 50 are examples of the control unit U1. The controller 10, RAM 21, communication I / F 22, storage unit 23, and operation panel 24 are connected to a bus and are able to input and output information from each other.

[0028] The controller 10 includes a processor, a CPU (Central Processing Unit) 11, an edge correction unit 12, a color conversion unit 13, a halftone processing unit 14, a drive signal transmission unit 15, etc. The controller 10 controls the drive unit 50 and the print head 30 so that a print image IM5 is formed on the print medium ME0 based on an image acquired from either the host device HO1, a memory card (not shown), etc. The acquired image includes, for example, two colors for each pixel: R (red), G (green), and B (blue). 8 Tone (or 2 16 An RGB image, represented by RGB data with integer values ​​for gradation, etc., can be applied. The controller 10 can be configured using an SoC (System on a Chip) or the like.

[0029] The CPU 11 is the device that primarily handles information processing and control in the printer 2. The edge correction unit 12 may convert the resolution of the acquired image to the print resolution if the acquired image differs from the print resolution. This image adjusted to the print resolution will be called image IM1. The edge correction unit 12 detects the inner part F1 to be processed and, if necessary, the edge part E1 to be processed from image IM1 in units of pixels PX0 (see Figure 4), and generates a corrected image IM3 in which the amount of ink 36 ejected to the inner part F1 and, if necessary, the edge part E1 to be processed is reduced. If image IM1 is an RGB image, the corrected image IM3 will also be an RGB image. Alternatively, the edge correction unit 12 may generate the corrected image IM3 before the resolution conversion and convert the resolution of the corrected image IM3 to the print resolution.

[0030] The color conversion unit 13 refers to a color conversion LUT (lookup table) which defines the correspondence between the gradation values ​​of R, G, and B and the gradation values ​​of C (cyan), M (magenta), Y (yellow), and K (black), and converts the RGB data representing the corrected image IM3 into ink amount data DA1. The ink amount data DA1 is, for example, set for each pixel PX0 to C, M, Y, and K 8 Tone (or 2 16It has integer values ​​for gradation, etc. The ink amount data DA1 represents the amount of C, M, Y, and K ink 36 used in units of pixel PX0. The halftone processing unit 14 reduces the number of gradations in the gradation values ​​of each pixel PX0 constituting the ink amount data DA1 by performing halftone processing using one of the following methods: dithering, error diffusion, etc., thereby generating dot data DA2. The dot data DA2 represents the formation state of the dots 38 of the ink droplets 37 in units of pixel PX0, and indicates the position of the dots 38 formed by the ink 36 from the print head 30. The dot data DA2 may be binary data representing the presence or absence of dot formation, or it may be multi-level data with three or more gradations that can handle dots of different sizes, such as small, medium, and large.

[0031] The drive signal transmission unit 15 generates a drive signal SG1 from the dot data DA2 and outputs it to the drive circuit 31 of the print head 30. The drive signal SG1 corresponds to the voltage signal applied to the drive element 32 of the print head 30. For example, if the dot data DA2 is "dot formation", the drive signal transmission unit 15 outputs a drive signal SG1 that ejects ink droplets for dot formation. Also, if the dot data DA2 is data with three or more values, the drive signal transmission unit 15 outputs a drive signal SG1 that ejects ink droplets for large dots if the dot data DA2 is "large dot formation", and outputs a drive signal SG1 that ejects ink droplets for small dots if the dot data DA2 is "small dot formation".

[0032] Each of the above parts 11 to 15 may be composed of an ASIC (Application Specific Integrated Circuit), and may directly read the data to be processed from RAM 21 or directly write the processed data to RAM 21.

[0033] As shown in Figure 2, the print head 30 has multiple nozzle rows 33 on its nozzle surface 30a, each row having multiple nozzles 34 capable of ejecting ink droplets 37 onto the printing medium ME0, arranged in the nozzle alignment direction D4 at a predetermined nozzle pitch interval. Here, a nozzle means a small hole from which ink droplets are ejected, and a nozzle row means an arrangement of multiple nozzles. The nozzle surface 30a is the ejection surface for the ink droplets 37. The multiple nozzles 34 in each nozzle row 33 may be arranged in a staggered pattern in the nozzle alignment direction D4, or in other words, in two rows in the nozzle alignment direction D4. The nozzle alignment direction D4 may intersect with the feed direction D3, or it may intersect with the main scanning direction which intersects with the feed direction D3, as in a serial printer, etc. The multiple nozzle rows 33 include a C nozzle row 33C capable of ejecting C ink 36, an M nozzle row 33M capable of ejecting M ink 36, a Y nozzle row 33Y capable of ejecting Y ink 36, and a K nozzle row 33K capable of ejecting K ink 36. Each ink droplet 37 is ejected from the nozzle 34 onto the printing medium ME0, targeting the pixel PX0. Naturally, a C dot 38 is formed on the printing medium ME0 from a C ink droplet 37, an M dot 38 is formed on the printing medium ME0 from an M ink droplet 37, a Y dot 38 is formed on the printing medium ME0 from a Y ink droplet 37, and a K dot 38 is formed on the printing medium ME0 from a K ink droplet 37. The printer 2 may have multiple print heads 30.

[0034] The drive unit 50, controlled by the controller 10, moves the printing medium ME0 along the transport path 59 in the feed direction D3 by driving the roller drive unit 55. The roller drive unit 55 includes a transport roller pair 56 and a discharge roller pair 57. The roller drive unit 55 is composed of a servo motor and moves the printed medium ME0 in the feed direction D3 by rotating the drive transport roller of the transport roller pair 56 and the drive discharge roller of the discharge roller pair 57 according to the control of the controller 10. The control unit U1 can be said to control the relative positional relationship between the print head 30 and the printing medium ME0. The printing medium ME0 is the substrate that holds the printed image. The material of the printing medium ME0 is not particularly limited and can be various materials such as paper, resin, or metal. The shape of the printing medium ME0 is also not particularly limited and can be various shapes such as rectangles or rolls, and it may also be three-dimensional.

[0035] The platen 58 is located below the transport path 59 and supports the printing medium ME0 by contacting it in the transport path 59. The print head 30, controlled by the controller 10, is equipped with a drive circuit 31 and drive elements 32, etc., and adheres ink 36 to the printing medium ME0 supported by the platen 58 by ejecting ink droplets 37 toward the printing medium ME0. Therefore, it can be said that the control unit U1 controls the ejection of ink droplets 37 from the print head 30. The drive circuit 31 applies a voltage signal to the drive element 32 according to the drive signal SG1 input from the drive signal transmission unit 15. The drive element 32 may be a piezoelectric element that applies pressure to the ink 36 in a pressure chamber communicating with the nozzle 34, or it may be a drive element that generates bubbles in the pressure chamber using heat to eject ink droplets 37 from the nozzle 34. Ink 36 is supplied to the pressure chamber of the print head 30 from an ink supply unit 35, such as an ink cartridge or ink tank. The ink 36 in the pressure chamber is ejected as ink droplets 37 from the nozzle 34 toward the printing medium ME0 by the drive element 32. As a result, dots 38 of ink droplets 37 are formed on the printing medium ME0, and a printed image IM5 represented by a pattern of dots 38 is formed on the printing medium ME0. Therefore, it can be said that the control unit U1 controls the ejection of ink 36 from the print head 30 to the printing medium ME0 so that the dots 38 constituting the printed image IM5 are formed on the printing medium ME0.

[0036] RAM 21 stores images and other data received from the host device HO1 or memory (not shown). The communication interface 22 is connected to the host device HO1 by wire or wireless connection and inputs and outputs information to the host device HO1. The host device HO1 includes computers such as personal computers and tablet terminals, mobile phones such as smartphones, digital cameras, digital video cameras, etc. The storage unit 23 may be a non-volatile semiconductor memory such as flash memory, or a magnetic storage device such as a hard disk. The operation panel 24 includes an output unit 25 such as a liquid crystal panel for displaying information, an input unit 26 such as a touch panel for receiving operations on the display screen, etc.

[0037] Incidentally, it is conceivable that the dot 38, which originates from liquid ink droplets, expands beyond the pixel PX0, causing the dark area surrounded by the white area, such as the black area, to widen. In particular, when ink droplets that land on the printing medium ME0 bleed, the dark area may expand too much, resulting in a decrease in the print quality of characters or causing barcodes to become non-standard. Furthermore, the dark area may also include thin diagonal lines, such as the sweeping strokes of small characters. Here, in order to prevent a decrease in print quality due to ink droplet bleeding, it is assumed that the edge E0 of a dark area will be detected and that ink droplets will not be ejected across the entire edge E0.

[0038] Figure 13 schematically shows a comparative example of forming a printed image IM95 from an input image IM91, which is an RGB image. The upper part of Figure 13 shows the input image IM91, which has a black downward-sloping region, such as the leftward stroke of a small character. The middle part of Figure 13 shows the corrected image IM93. The lower part of Figure 13 shows the printed image IM95 on the printing medium ME0. The images shown in Figure 13 (IM91, IM93) have multiple pixels PX0 arranged in the X direction as an example of the first direction D1, and in the Y direction as an example of the second direction D2 which is orthogonal to the first direction D1. In the images shown in Figure 13 (IM91, IM93), pixels PX0 in the black region are hatched. The gradation value (R,G,B) of pixels PX0 in the white region is assumed to be (255,255,255), and the gradation value (R,G,B) of pixels PX0 in the black region is assumed to be (0,0,0).

[0039] The black, downward-sloping area in the input image IM91 shown in Figure 13 is approximately a 4-pixel diagonal line in both the X and Y directions. From this input image IM91, the edge E0 of the black area is detected, as shown in the corrected image IM93 in Figure 13. When the total pixel value of edge E0 is replaced from (0,0,0) to (255,255,255), ink droplets are not ejected across the entire edge E0. As a result, the 4-pixel diagonal line in both the X and Y directions becomes effectively a 2-pixel diagonal line, and a printed image IM95 with a 2-dot diagonal line in both the X and Y directions is formed on the printing medium ME0. Although not shown, a 3-pixel diagonal line in both the X and Y directions becomes effectively a 1-pixel diagonal line. Consequently, the diagonal lines become too thin, and the degradation of objects containing diagonal lines becomes noticeable. The same applies when the input image IM91 has a black, downward-sloping area, such as the rightward stroke of a small character.

[0040] In this specific example, the amount of ink 36 dispensed slightly inside the edge along either of the two diagonal directions is reduced. This suppresses the deterioration of print quality due to ink bleeding while avoiding the problem of diagonal edges of objects, such as thin diagonal lines including the sweeping strokes of small characters, becoming too thin. The following describes specific examples of print control processes for implementing the dot data generation method, with reference to Figures 3-12B.

[0041] (3) Specific examples of print control processing: Figure 3 schematically illustrates the print control process performed by the controller 10. Figure 4 schematically illustrates how a corrected image IM3 is generated from the input image with a reduced ink amount in the inner part F1 of the processing target. The input image is assumed to be an RGB image, and the images (IM1, IM3) shown in Figure 4 are assumed to be RGB images. In the images (IM1, IM3) shown in Figure 4, the surrounding region AR2 is a white region with pixel values ​​(R,G,B) of (255,255,255), and the darker region AR3, which is darker than the surrounding region AR2, is a black region with pixel values ​​(R,G,B) of (0,0,0). Figure 4 also shows the reference pattern P0 applied to image IM1. Figure 5 schematically illustrates an example of combining individual reference patterns. In Figures 4 and 5, the pixels PX0 in the dark region AR3, including the reference pattern P0, are hatched. Figure 6 schematically illustrates how a printed image IM5 is formed from dot data DA2. In Figure 3, steps S102 to S104 correspond to the detection process ST1 and the detection process. Steps S106 to S112 correspond to the generation process ST2. Step S114 corresponds to the printing process ST3. Steps S108 to S114 correspond to the ejection control process. Hereafter, the term "step" may be omitted, and the step number may be indicated in parentheses.

[0042] When the print control process shown in Figure 3 starts, the controller 10 performs a detection process in the edge correction unit 12 to detect the diagonally oriented inner part F1 of the processing target from the image IM1, which is an RGB image (S102). As shown in Figure 4, image IM1 has multiple pixels PX0 arranged in the X direction as an example of the first direction D1, and in the Y direction as an example of the second direction D2 intersecting the first direction D1. The feed direction D3 shown in Figures 1 and 2 may be either the X direction or the Y direction. In Figure 4, the X direction and the Y direction are orthogonal to each other. Note that the Y direction may be applied to the first direction D1, and the X direction may be applied to the second direction D2. In Figure 4, the detection target area AR1 of the inner part F1 to be processed is the entire image IM1. Note that the edges E0 present in the detection target area AR1 are areas of 1 pixel adjacent to the surrounding area AR2 in the X direction or Y direction in the dense area AR3, as shown in the corrected image IM3 shown in Figure 8.

[0043] Image IM1, shown in Figure 4, includes a dark region AR3, which contains a black, downward-sloping region AR4 representing the leftward stroke of a character, and a black, downward-sloping region AR5 representing the rightward stroke of a character. This specific example assumes the detection of the inner part F1 to be processed from these regions (AR4, AR5). The inner part F1 to be processed can be detected by pattern matching using the reference pattern P0 shown in Figures 4 and 5. Here, a pattern means a set of features such as signals or pictures, and the relationships between features. Pattern matching means comparing a certain pattern with a set of pre-prepared patterns based on predetermined evaluation criteria. Pattern matching is not limited to comparing images with images; it is acceptable as long as the state of the pixel of interest and its surrounding pixels can be compared between the image and the pattern based on evaluation criteria, such as signals represented by 0s and 1s. The reference pattern P0 shown in Figure 5 is a combination of two selected from the individual reference patterns P1 to P4, and can be considered a training image for image IM1. Figure 4 shows that the reference pattern P0 is a combination of the individual reference patterns P1 and P2. Reference patterns P1 to P4 are rectangular (including square). Reference patterns P1 to P4 shown in Figures 4 and 5 are 3x3 pixel squares. For the sake of explanation, pixels PX0 included in the surrounding region AR2 will be called faint pixels, and pixels PX0 included in the dark region AR3 will be called dark pixels. The faint pixels shown in Figures 4 and 5 are white pixels with pixel values ​​(R,G,B) of (255,255,255), and the pixel values ​​of faint pixels in reference patterns P1 to P4 are also (R,G,B)=(255,255,255). The dark pixels shown in Figures 4 and 5 are black pixels with pixel values ​​(R,G,B) of (0,0,0), and the pixel values ​​of dark pixels in reference patterns P1 to P4 are also (R,G,B)=(0,0,0). The size of the reference pattern can be 5x5 pixels, or it can be a non-square size such as 3x5 pixels or 5x3 pixels.

[0044] The controller 10 sequentially selects a target pixel PX1 from among multiple pixels PX0 included in the image IM1, and performs pattern matching by applying the reference pattern P0 to a rectangular determination region AD0 centered on the target pixel PX1. The determination region AD0 is the same size as the reference patterns P1 to P4, and in the example shown in Figure 4, it is a 3x3 pixel region centered on the target pixel PX1. The controller 10 detects the target pixel PX1 as the inner part F1 to be processed if the arrangement of light and dark pixels in the determination region AD0 matches the arrangement of light and dark pixels in either of the individual reference patterns P1 or P2. If the pixel arrangement in the determination region AD0 does not match the pixel arrangement of either the reference patterns P1 or P2, the target pixel PX1 is not the inner part F1 to be processed. In Figure 4, the reference pattern P1 has a pixel arrangement for detecting the inner part F1 to be processed along the upper left edge of the downward-sloping region AR4, and the reference pattern P2 has a pixel arrangement for detecting the inner part F1 to be processed along the upper right edge of the downward-sloping region AR5. The pixel arrangement of reference pattern P1 is an example of the first condition as an inside edge condition, and the pixel arrangement of reference pattern P2 is an example of the second condition as an inside edge condition. For example, since the pixel arrangement of determination region AD1 matches the pixel arrangement of reference pattern P1, the pixel of interest PX1 in determination region AD1 is detected as the inner part F1 to be processed. Since the pixel arrangement of determination region AD2 matches the pixel arrangement of reference pattern P2, the pixel of interest PX1 in determination region AD2 is detected as the inner part F1 to be processed.

[0045] As described above, the controller 10 detects the pixel PX1 as the inner part F1 to be processed when the rectangular determination area AD0 centered on the pixel PX1 of interest included in the detection target area AR1 satisfies a predetermined inner edge condition that includes the surrounding area AR2 and the dense area AR3.

[0046] Referring to Figure 5, we will refer to each pixel PX0 included in the 3x3 pixel determination area AD0 as follows. The central pixel PX0 in the determination region AD0 is the pixel of interest PX1. In the determination region AD0, the pixels PX0 adjacent to the pixel of interest PX1 in the first direction D1 and the second direction D2 will be called adjacent pixels PX2. The pixel of interest PX1 and the four adjacent pixels PX2 form a cross shape. Therefore, in the determination region AD0, the pixel of interest PX1 and the four adjacent pixels PX2 will be called the cross region PX10. The pixels PX0 at the four corners of the determination region AD0 will be called corner pixels PX3. Thus, the determination region AD0 includes the cross region PX10 and the corner pixels PX3 at the four corners. The four corner pixels PX3 include the first corner pixel PX31, the second corner pixel PX32, the third corner pixel PX33, and the fourth corner pixel PX34. The positions of these corner pixels (PX31~PX34) are relative, but in the determination region AD0, the second corner pixel PX32 is not diagonally opposite the first corner pixel PX31. Figure 5 shows that the first corner pixel PX31 is located in the upper left of the determination region AD0, the second corner pixel PX32 is located in the upper right of the determination region AD0, the third corner pixel PX33 is located in the lower right of the determination region AD0, and the fourth corner pixel PX34 is located in the lower left of the determination region AD0. If the first corner pixel PX31 is located in the upper left of the determination region AD0, the second corner pixel PX32 may be located in the lower left of the determination region AD0. Of course, the first corner pixel PX31 may also be located in the upper right, lower right, or lower left of the determination region AD0.

[0047] Four reference patterns P1 to P4, shown in Figure 5, are possible for the reference pattern P0 used to detect the inner part F1 of the processing target. Reference pattern P1 has an arrangement where the first corner pixel PX31 is a light pixel and the remaining 8 pixels are dark pixels. Reference pattern P2 has an arrangement where the second corner pixel PX32 is a light pixel and the remaining 8 pixels are dark pixels. Reference pattern P3 has an arrangement where the third corner pixel PX33 is a light pixel and the remaining 8 pixels are dark pixels. Reference pattern P4 has an arrangement where the fourth corner pixel PX34 is a light pixel and the remaining 8 pixels are dark pixels. Of reference patterns P1 to P4, reference patterns P1 and P3 have pixel arrangements that detect the inner part F1 of the processing target in the downward-sloping left region AR4, while reference patterns P2 and P4 have pixel arrangements that detect the inner part F1 of the processing target in the downward-sloping right region AR5. By combining either reference pattern P1 or P3 with either reference pattern P2 or P4, the amount of ink in the inner part F1 of the processing target can be reduced in both the left-downward region AR4 and the right-downward region AR5. In this specific example, in order to prevent the amount of ink inside the diagonal lines in the printed image IM5 from being reduced too much, either reference pattern P1 or P3 is used for the left-downward region AR4, and either reference pattern P2 or P4 is used for the right-downward region AR5. That is, reference pattern P1 and reference pattern P3 are not combined, and reference pattern P2 and reference pattern P4 are not combined. Figure 4 shows that the combination of reference patterns P1 and P2 is used as reference pattern P0. Reference pattern P0 may also be a combination of reference patterns P1 and P4, a combination of reference patterns P3 and P2, or a combination of reference patterns P3 and P4. First, we will explain the case where reference pattern P0 is a combination of reference patterns P1 and P2, as shown in Figure 4.

[0048] When the determination area AD0 matches the reference pattern P1, it means that the cross-shaped area PX10 is in the dark area AR3, the first corner pixel PX31 is in the surrounding area AR2, and the three corner pixels PX3 excluding the first corner pixel PX31 are in the dark area AR3. The determination area AD0 matches the reference pattern P1 when it is a pixel that is one pixel inward from the top left edge in the left-downward area AR4. Here, we will call the condition in which the determination area AD0 matches the reference pattern P1 the first condition. When the controller 10 finds that the determination area AD0 satisfies the first condition, it detects the pixel of interest PX1 as the inner part F1 to be processed. When the determination area AD0 matches the reference pattern P2, it means that the cross-shaped area PX10 is in the dark area AR3, the second corner pixel PX32 is in the surrounding area AR2, and the three corner pixels PX3 excluding the second corner pixel PX32 are in the dark area AR3. The determination area AD0 matches the reference pattern P2 when it is a pixel that is one pixel inward from the upper right edge in the downward sloping area AR5. Here, we will call the condition in which the determination area AD0 matches the reference pattern P2 the second condition. When the controller 10 finds that the determination area AD0 satisfies the second condition, it detects the pixel of interest PX1 as the inner part F1 to be processed.

[0049] After detecting the inner portion F1 to be processed, the controller 10, if necessary, performs a detection process in the edge correction unit 12 to detect a portion of edge E0 from image IM1 as the edge portion E1 to be processed (S104). Details of the process in S104 will be described later.

[0050] In S106, the controller 10 performs an edge correction in the edge correction unit 12 to reduce the amount of ink in the inner part F1 of the processing target. As a result, the process in S106 can be described as a process of thinning or reducing the size of the dots 38 in the inner part F1 of the processing target. In the example shown in Figures 4 and 6, the controller 10 generates dot data DA2 from the image IM1 so that ink 36 is not ejected from the print head 30 to the inner part F1 of the processing target. For example, the controller 10 generates a corrected image IM3 by replacing the pixel values ​​(R, G, B) of the inner part F1 of the processing target in the image IM1 from (0, 0, 0) to (255, 255, 255). The amount of ink in the inner part F1 of the processing target may be reduced to, for example, 1 to 50% of the amount before correction. For example, the pixel values ​​(R, G, B) of the inner part F1 of the processing target may be replaced with (128, 128, 128), which is about 50% of the amount of ink before correction. Furthermore, the pixel values ​​shown in this specification are merely examples to illustrate this specific example clearly and can be changed in various ways. The same applies to the following.

[0051] When a target edge E1 is detected, the controller 10 performs a correction in the edge correction unit 12 to reduce the amount of ink in the target edge E1 (S108). Details of S108 will be described later.

[0052] In S110, the controller 10 performs a color conversion process in the color conversion unit 13 to convert the corrected image IM3 into ink amount data DA1. For pixels PX0 of the inner part F1 to be processed, if the pixel value (R,G,B) of the corrected image IM3, which is an RGB image, is (255,255,255), it is converted to a pixel value where no ink droplet 37 is ejected, for example, (C,M,Y,K)=(0,0,0,0). After the color conversion process, the controller 10 performs a halftone process in the halftone processing unit 14 to convert the ink amount data DA1 into dot data DA2 (S112). For pixels PX0 of the inner part F1 to be processed, if the pixel value (C,M,Y,K) of the ink amount data DA1 is (0,0,0,0), C, M, Y, and K are all converted to a value indicating no dot, for example, 0. Figure 6 shows a schematic representation of dot data DA2 in the print medium ME0 of the corrected image IM3, where dots 38, for example, large dots, are formed on the dark pixels. For clarity, a small gap is shown in the inner part F1 of the processing target in the print medium ME0 of Figure 6, but the gap is not visible once the ink droplets 37 bleed. As described above, the controller 10 generates dot data DA2 from the image IM1 such that the amount of ink 36 ejected from the print head 30 to the inner part F1 of the processing target is reduced, including 0. In this specification, "such as reducing the amount of ink 36 ejected to the inner part F1 of the processing target, including 0" means, as explained in S106 above, "reducing the amount of ink ejected" or "preventing ejection altogether" compared to the case without correction.

[0053] After halftone processing, the controller 10 generates a drive signal SG1 based on the dot data DA2 and transmits the drive signal SG1 to the drive circuit 31 of the print head 30 (S114), thereby ending the print control process. The print head 30 ejects K ink droplets 37 according to the drive signal SG1 so that multiple dots 38 are formed in the dark pixels, as shown in the print medium ME0 of Figure 6. As a result, a print image IM5 represented by a pattern of dots 38 is formed on the print medium ME0. The printer 2 ejects ink 36 from the print head 30 onto the print medium ME0 based on the dot data DA2.

[0054] As explained above, the amount of ink 36 dispensed to the slightly inward portion of the edge along either of the two diagonal directions is reduced. This makes it possible to suppress the deterioration of print quality due to ink 36 bleeding while avoiding the inconvenience of diagonal edges of objects, such as thin diagonal lines including the sweeping strokes of small characters, becoming too thin.

[0055] Next, we will explain the case where the reference pattern P0 is a combination of reference patterns P3 and P4, as shown in Figure 7. Figure 7 schematically shows another example of generating a corrected image IM3 from the input image with reduced ink volume in the inner part F1 of the processing target. In the example shown in Figure 7, in the determination region AD0 shown in Figure 5, the first corner pixel PX31 is in the position of the third corner pixel PX33, and the second corner pixel PX32 is in the position of the fourth corner pixel PX34. The determination area AD0 matches the reference pattern P3 when it is a pixel located one pixel inward from the bottom right edge in the downward-sloping area AR4. The condition for determination area AD0 to match the reference pattern P3 is an example of the first condition. When the controller 10 finds that determination area AD0 satisfies the first condition, it detects the pixel of interest PX1 as the inner part F1 to be processed. For example, since the pixel arrangement of determination area AD3 matches the pixel arrangement of reference pattern P3, the pixel of interest PX1 in determination area AD3 is detected as the inner part F1 to be processed. Also, the determination area AD0 matches the reference pattern P4 when it is a pixel located one pixel inward from the bottom left edge in the downward-sloping area AR5. The condition for determination area AD0 to match the reference pattern P2 is an example of the second condition. When the controller 10 finds that determination area AD0 satisfies the second condition, it detects the pixel of interest PX1 as the inner part F1 to be processed. For example, since the pixel arrangement of the determination region AD4 matches the pixel arrangement of the reference pattern P4, the pixel of interest PX1 in the determination region AD4 is detected as the inner part F1 of the processing target.

[0056] In S106, the controller 10 performs an edge correction in the edge correction unit 12 to reduce the amount of ink in the inner part F1 of the processing target. Subsequently, through the processing in S110 to S114, dot data DA2 is generated from the image IM1 so that the amount of ink 36 ejected from the print head 30 to the inner part F1 of the processing target is reduced, including 0, and the printed image IM5 is formed. In the above cases as well, it is possible to suppress the deterioration of print quality due to ink 36 bleeding while avoiding the inconvenience of diagonal edges of objects, such as thin diagonal lines, becoming too thin.

[0057] Incidentally, bleeding of edges along the X and Y directions can cause the dark area to expand too much, potentially degrading the print quality of characters or rendering barcodes non-standard. For example, if a black line consisting of three pixels aligned in the X direction is oriented in the Y direction, and ink droplets are not ejected across the entire edge E0 of the black area to prevent a decrease in print quality due to ink bleeding, the width of the black line will decrease from three pixels to one pixel. If the black line is a barcode, the barcode may become too thin to be read. If the black line is an object containing thin lines such as characters, the degradation of the object will become more noticeable. In this specific example, by limiting the reduction of ink volume to only a portion of the edge area in the S104 and S108 processes shown in Figure 3, it is possible to suppress the deterioration of fine lines while also suppressing the decline in print quality due to ink bleeding.

[0058] Figure 8 schematically illustrates how a printed image IM5 is formed from an input image with reduced ink volume in the target edge area E1. In step S104 shown in Figure 3, the controller 10 performs a detection process in the edge correction unit 12 to detect a portion of edge E0 from the RGB image IM1 as the edge portion E1 to be processed.

[0059] Here, in the X direction, the edge present on one side of the dense region AR3, which is on both the left and right sides, is defined as the first edge E11. In the Y direction, the edge present on one side of the edge present on both the upper and lower sides of the dense region AR3 is defined as the second edge E12. Figure 8 shows that the first edge E11 is on the right side of the dense region AR3, and the second edge E12 is on the lower side of the dense region AR3. The first edge E11 may also be on the left side of the dense region AR3 instead of the right side. That is, the first edge E11 is not present on both sides of the dense region AR3 in the X direction. The second edge E12 may also be on the upper side of the dense region AR3 instead of the lower side. That is, the second edge E12 is not present on both sides of the dense region AR3 in the Y direction. Figure 8 shows that both the first edge portion E11 and the second edge portion E12 are detected as the edge portion E1 to be processed. The controller 10 may detect the first edge portion E11 as the edge portion E1 to be processed without including the second edge portion E12, or it may detect the second edge portion E12 as the edge portion E1 to be processed without including the first edge portion E11. When the Y direction is longer than the X direction, as in the dense region AR3 shown in Figure 8, it is preferable that the edge portion E1 to be processed includes the first edge portion E11.

[0060] The edge region E1 to be processed can be detected by pattern matching using the reference pattern P10 shown in Figure 8. The reference pattern P10 is a collective term for the rectangular reference patterns P11 to P15, and can be considered the training image for image IM1. The reference patterns P11 to P15 shown in Figure 8 are 3x3 pixel squares. The faint pixels shown in Figure 8 are white pixels with pixel values ​​(R,G,B) of (255,255,255), including those within the reference pattern P10, and the dark pixels shown in Figure 8 are black pixels with pixel values ​​(R,G,B) of (0,0,0), including those within the reference pattern P10. Here too, the size of the reference pattern can be 5x5 pixels, or it can be a non-square size such as 3x5 pixels or 5x3 pixels.

[0061] The controller 10 sequentially selects a target pixel PX1 from among multiple pixels PX0 included in the image IM1, and performs pattern matching by applying the reference pattern P10 to a rectangular determination area AD0 centered on the target pixel PX1. The determination area AD0 is the same size as the reference patterns P11 to P15, and in the example shown in Figure 8, it is a 3x3 pixel area centered on the target pixel PX1. If the arrangement of light and dark pixels in the determination area AD0 matches the arrangement of light and dark pixels in any of the reference patterns P11 to P15, the controller 10 detects the target pixel PX1 as the edge area E1 to be processed. If the pixel arrangement of the determination area AD0 does not match any of the pixel arrangements of the reference patterns P11 to P15, the target pixel PX1 is not the edge area E1 to be processed. For example, since the pixel arrangement of the determination area AD5 matches the pixel arrangement of the reference pattern P11, the target pixel PX1 in the determination area AD5 is detected as the edge area E1 to be processed. Since the pixel arrangement of the determination area AD6 matches the pixel arrangement of the reference pattern P12, the pixel of interest PX1 in the determination area AD6 is detected as the edge portion E1 to be processed. As described above, the controller 10 detects at least one of the edges E0 present in the detection target area AR1 as the edge portion E1 to be processed, which is a first edge portion E11 located on one side of the dense area AR3 in the first direction D1, and a second edge portion E12 located on one side of the dense area AR3 in the second direction D2.

[0062] In S108 shown in Figure 3, the controller 10 performs an edge correction in the edge correction unit 12 to reduce the amount of ink in the edge area E1 to be processed. As a result, the process in S108 can be described as a process of thinning or reducing the size of the dots 38 in the edge area E1 to be processed. In the example shown in Figure 8, the controller 10 generates dot data DA2 from the image IM1 so that ink 36 is not ejected from the print head 30 to the edge area E1 to be processed. For example, the controller 10 generates a corrected image IM3 by replacing the pixel values ​​(R,G,B) of the edge area E1 to be processed in the image IM1 from (0,0,0) to (255,255,255). The amount of ink in the edge area E1 to be processed may be reduced to, for example, 1 to 50% of the amount before correction. For example, the pixel values ​​(R,G,B) of the edge area E1 to be processed may be replaced with (128,128,128), which is about 50% of the amount of ink before correction.

[0063] After processing in S108, the controller 10 performs a color conversion process in the color conversion unit 13 to convert the corrected image IM3 into ink amount data DA1 (S110). For pixels PX0 of the edge portion E1 to be processed, if the pixel value (R,G,B) of the corrected image IM3, which is an RGB image, is (255,255,255), it is converted to a pixel value where no ink droplet 37 is ejected, for example, (C,M,Y,K)=(0,0,0,0). After the color conversion process, the controller 10 performs a halftone process in the halftone processing unit 14 to convert the ink amount data DA1 into dot data DA2 (S112). For pixels PX0 of the edge portion E1 to be processed, if the pixel value (C,M,Y,K) of the ink amount data DA1 is (0,0,0,0), C, M, Y, and K are all converted to a value indicating no dot, for example, 0. Figure 8 shows a schematic representation of dot data DA2 in the print medium ME0, where dots 38, for example, large dots, are formed on the dark pixels of the corrected image IM3. As shown in Figure 3, the processes S102 to S112 are performed, generating dot data DA2 from image IM1 such that the amount of ink 36 ejected from the print head 30 to the inner part F1 and the edge part E1 of the processing target is reduced, including 0. As shown in Figure 3, the process S114 is performed, forming a printed image IM5 with reduced ink amounts in the inner part F1 and the edge part E1 of the processing target.

[0064] As shown in Figure 3, the processing S104 and S108 is performed, which reduces the amount of ink 36 ejected to at least one of the edge portions (E11, E12) on one side of the dense region AR3, rather than the entire edge E0 present in the detection target region AR1. This makes it possible to suppress the deterioration of print quality due to ink bleeding 36 while avoiding the problem of objects such as barcodes and fine characters becoming too thin. Furthermore, it makes it possible to avoid the problem of diagonal edges of objects such as thin diagonal lines becoming too thin.

[0065] Furthermore, as illustrated in Figure 9, in order to suppress the visibility of blank spaces (see Figure 6) in the area corresponding to the inner part F1 of the processing target in the printed image IM5, a small amount of ink 36 may be ejected from the print head 30 onto the inner part F1 of the processing target. Figure 9 schematically shows another example of forming the printed image IM5 from dot data DA2. In S106 shown in Figure 3, the controller 10 performs an edge correction in the edge correction unit 12 to reduce the amount of ink in the inner part F1 to be processed to, for example, 1-50% of the amount before correction. For example, the pixel values ​​(R, G, B) of the inner part F1 to be processed may be replaced with (64, 64, 64), which represents about 25% of the amount of ink before correction.

[0066] In step S108 shown in Figure 3, the controller 10 performs an edge correction in the edge correction unit 12 to reduce the amount of ink in the processing target edge E1 to less than the amount of ink in the processing target inner part F1. For example, as shown in Figure 8, the controller 10 generates a corrected image IM3 by replacing the pixel values ​​(R,G,B) of the processing target edge E1 in the image IM1 from (0,0,0) to (255,255,255). In S110, the color conversion unit 13 performs a color conversion process to convert the corrected image IM3 into ink quantity data DA1. For pixels PX0 of the processing target edge part E1, if the pixel values ​​(R,G,B) of the corrected image IM3, which is an RGB image, are (255,255,255), the pixel values ​​are converted to a pixel value where no ink droplet 37 is ejected, for example, (C,M,Y,K)=(0,0,0,0). For pixels PX0 of the processing target inner part F1, if the pixel values ​​(R,G,B) of the corrected image IM3 are (64,64,64), the pixel values ​​are converted to a pixel value where the size of the K ink droplet 37 becomes smaller, for example, from a large dot equivalent to a small dot equivalent, for example, (C,M,Y,K)=(0,0,0,63). After the color conversion process, the controller 10 performs a halftone processing in the halftone processing unit 14 to convert the ink quantity data DA1 into dot data DA2 (S112). For pixels PX0 of the edge area E1 to be processed, if the pixel value (C, M, Y, K) of the ink amount data DA1 is (0,0,0,0), then C, M, Y, and K are all converted to a value indicating no dot, for example, 0. For pixels PX0 of the inner area F1 to be processed, if the pixel value (C, M, Y, K) of the ink amount data DA1 is (0,0,0,64), then K is converted to a value indicating a small dot, for example, 1. After halftone processing, the printed image IM5 is formed on the printing medium ME0 (S114).

[0067] In the example shown in Figures 8 and 9, the controller 10 reduces the amount of ink 36 ejected from the print head 30 to the processing target edge E1 to less than the amount of ink 36 ejected from the print head 30 to the processing target inner part F1. By reducing the amount of ink ejected to the processing target edge E1 compared to the amount ejected to the processing target inner part F1, the bleeding of ink 36 that spreads from the edge is suppressed. In particular, when no ink 36 is ejected from the print head 30 to the processing target edge E1, the bleeding of ink 36 that spreads from the edge is effectively suppressed. Therefore, the reduction in print quality of objects such as barcodes and fine characters due to ink bleeding can be further suppressed.

[0068] Furthermore, some of the above-described processes may be performed by the host device HO1. In this case, the combination of the controller 10, the drive unit 50, and the host device HO1 is an example of the control unit U1, and the combination of the printer 2 and the host device HO1 is an example of the printing device 1. The entity that performs the above-described processes is not limited to the CPU, but may be an electronic component other than the CPU, such as an ASIC. Of course, multiple CPUs may cooperate to perform the above-described processes, or a CPU and other electronic components (such as an ASIC) may cooperate to perform the above-described processes.

[0069] To set the amount of ink 36 to be ejected to the inner part F1 to be processed, the printing device 1 can display the inner ink amount specification screen 520, as illustrated in Figure 10A, on at least one of the output unit 25 of the operation panel 24 and the display device DU1 of the host device HO1. Figure 10A schematically shows an example of the display of the inner ink amount specification screen 520. The inner ink amount specification screen 520 shown in Figure 10A includes the "no ink ejection" item 221, the "small ink ejection" item 222, etc. The "no ink ejection" item 221 is an option that does not eject ink droplets 37 to the inner part F1 to be processed. The "small ink ejection" item 222 is an option that ejects ink droplets 37 equivalent to small dots to the inner part F1 to be processed. For example, the controller 10 displays the inner ink amount specification screen 520 on the output unit 25 and accepts the selection of one of the multiple options (221, 222) at the input unit 26 of the operation panel 24. If the selection of the "no ink ejection" item 221 is accepted, the controller 10 generates a corrected image IM3 in S106 shown in Figure 3 by replacing the pixel values ​​(R, G, B) of the inner part F1 to be processed with (255, 255, 255). As a result, as shown in Figure 6, no dots 38 are formed on the inner part F1 to be processed. When the controller 10 receives the "small ink ejection" item 222, it generates a corrected image IM3 in S106 shown in Figure 3 by replacing the pixel values ​​(R, G, B) of the inner part F1 to be processed with (64, 64, 64). As a result, small dots are formed on the inner part F1 to be processed, as shown in Figure 9. Of course, the host device HO1 may display the inner ink amount specification screen 520 on the display device DU1 and accept the specification of one of the multiple options (221, 222) at an input unit not shown.

[0070] Based on the above, if the "no ink ejection" item 221 is specified, the printer 1 generates dot data DA2 from image IM1 so that ink 36 is not ejected from the print head 30 to the inner part F1 of the processing target. If the "low ink ejection" item 222 is specified, the printer 1 generates dot data DA2 from image IM1 so that the amount of ink 36 ejected from the print head 30 to the inner part F1 of the processing target is reduced to a range that does not become zero.

[0071] Furthermore, in order to switch the definition of the dense area AR3 in the print control process shown in Figure 3, the printing device 1 can display the dense area specification screen 540, as exemplified in Figure 10B, on at least one of the output unit 25 of the operation panel 24 and the display device DU1 of the host device HO1. Figure 10B schematically shows an example of the display of the dense area specification screen 540. The dark area specification screen 540 shown in Figure 10B includes multiple options 240 to be applied to the dark area AR3, such as the "black only" option 241 and the "other than white" option 242. The "black only" option 241 is an option to apply black (R,G,B)=(0,0,0) as an example of a predetermined color to the dark area AR3. The "other than white" option 242 is an option to apply a color other than white as an example of a predetermined color range to the dark area AR3. For example, the controller 10 displays the dark area specification screen 540 on the output unit 25 and accepts the selection of one of the multiple options (241,242) at the input unit 26 of the operation panel 24. If the controller 10 accepts the selection of the "black only" option 241, it applies black (R,G,B)=(0,0,0) to the dark area AR3 of the images (IM1,IM3) and reference patterns P0,P10 and performs the print control processing shown in Figure 3. When the controller 10 receives a "non-white" item 242, it applies all colors whose pixel values ​​(R,G,B) are not (255,255,255) to the images (IM1,IM3) and the dark region AR3 of the reference patterns P0,P10, and performs the print control processing shown in Figure 3. Of course, the host device HO1 may display the dark region specification screen 540 on the display device DU1 and accept the specification of one of the multiple options 240 at an input unit not shown. In either case, a color specification process ST4 is performed to accept the specification of an option to be applied to the dark region AR3 from among the multiple options 240, including the "black only" item 241 and the "non-white" item 242.

[0072] When item 241, "black only," is specified, the printer 1 treats pixel PX0 with (R,G,B)=(0,0,0) as the dark region AR3 of the images (IM1,IM3) and reference patterns P0,P10, and performs the print control processing shown in Figure 3. For example, the controller 10 detects pixel PX1 as the inner part F1 to be processed, where the arrangement of the surrounding region AR2 with (R,G,B)=(255,255,255) and the dark region AR3 with (R,G,B)=(0,0,0) in the image IM1 matches the arrangement of either reference pattern P1 or P2. When a predetermined color is specified, the control unit U1 detects pixel PX1 as the inner part F1 to be processed if the distribution of the dark region AR3 of the predetermined color and the surrounding region AR2 in the determination region AD0 satisfies the inner edge condition. The same applies to the edge part E1 to be processed.

[0073] If item 242, "other than white," is specified, the printer 1 treats pixel PX0, whose pixel value (R,G,B) is anything other than (255,255,255), as a dark region AR3 and performs the print control processing shown in Figure 3. For example, the controller 10 detects a pixel PX1 of interest as the inner part F1 of the image IM1, where the arrangement of the surrounding region AR2 with (R,G,B)=(255,255,255) and the dark region AR3 that is not (R,G,B)=(255,255,255) matches the arrangement of either reference pattern P1 or P2. The control unit U1, when a predetermined color range is specified, detects a pixel PX1 of interest as the inner part F1 of the processing target if the distribution of the dark region AR3 and the surrounding region AR2 within the predetermined color range satisfies the inner edge condition in the determination region AD0. The same applies to the edge part E1 of the processing target.

[0074] For example, if an object such as a thin diagonal line or a barcode is black and the "black only" item 241 is specified, a high-quality printed image IM5 can be obtained by reducing the amount of ink in the inner part F1 and edge part E1 of the object. For example, consider a case where you want to reduce the amount of ink in the inner part F1 and edge part E1 of characters, but it is difficult to add information such as "characters" to the image IM1. In this case, by reducing the amount of ink only for black, which is commonly used for characters, complex processing is not required to generate dot data DA2, and the pixels PX0 whose ink amount you want to reduce can be extracted from the original image IM1 and the ink amount of those pixels PX0 can be reduced. Also, if an object is a color other than white and the "other than white" item 242 is specified, a high-quality printed image IM5 can be obtained by reducing the amount of ink in the inner part F1 and edge part E1 of objects of colors other than black, even if the object is not black. Therefore, a high-quality printed image IM5 can be obtained depending on the color of the object, such as a thin diagonal line or a barcode. Furthermore, even if objects such as thin diagonal lines or barcodes are colors other than black, such as blue or red, the print control process shown in Figure 3 may be performed using a predetermined color included in the multiple options 240.

[0075] Furthermore, the surrounding region AR2 is not limited to the white region where (R,G,B)=(255,255,255). For example, if GR is an integer value greater than 128 and less than 255, the surrounding region AR2 may also be the region of light-colored pixels PX0 satisfying R≧GR, G≧GR, and B≧GR. In this case, the dark region AR3 will be a dark-colored region satisfying R≦GR-1, or G≦GR-1, or B≦GR-1. The predetermined color range included in the multiple options 240 may also be a color range satisfying R≦GR-1, or G≦GR-1, or B≦GR-1.

[0076] Furthermore, in order to switch the depth of the inner part F1 of the processing target in the print control process shown in Figure 3, the printing device 1 can display the edge depth specification screen 560, illustrated in Figure 10C, on at least one of the output unit 25 of the operation panel 24 and the display device DU1 of the host device HO1. Figure 10C schematically shows an example of the display of the edge depth specification screen 560. Figure 11 schematically illustrates the process of deepening the inner part F1 of the processing target to generate the corrected image IM3. For convenience, the first corner pixel PX31 and the second corner pixel PX32 are attached to the reference pattern P20.

[0077] The edge depth specification screen 560 shown in Figure 10C includes multiple options for specifying the depth of the inner part F1 to be processed, such as the "1-dot depth" item 261 and the "2-dot depth" item 262. The "1-dot depth" item 261 is an option to set the depth of the inner part F1 to be processed to 1 dot. The "2-dot depth" item 262 is an option to set the depth of the inner part F1 to be processed to approximately 2 dots in both the X and Y directions. For example, the controller 10 displays the edge depth specification screen 560 on the output unit 25 and accepts the selection of one of the multiple options (261, 262) at the input unit 26 of the operation panel 24. If the controller 10 accepts the selection of the "1-dot depth" item 261, in the detection process S102 shown in Figure 3, the controller 10 detects the inner part F1 to be processed from the image IM1 by pattern matching using the 3x3 pixel reference pattern P0 shown in Figure 5. When the controller 10 receives the specification for the "2-dot depth" item 262, it detects the inner part F1 to be processed from the image IM1 by pattern matching using the reference pattern P20 shown in Figure 11 in the detection process S102 shown in Figure 3. Of course, the host device HO1 may display the edge depth specification screen 560 on the display device DU1 and accept the specification of one of the multiple options (261, 262) at an input unit not shown. In either case, the edge depth specification process ST5 is performed to accept the specification of the depth of the inner part F1 to be processed. The controller 10 or the host device HO1 performs a detection process to detect the inner part F1 to be processed so that it is the specified depth.

[0078] The reference pattern P20 shown in Figure 11 includes 3x3 pixel reference patterns P1 and P2, and 5x5 pixel reference patterns P21 and P22. The 3x3 pixel reference pattern P1, as shown in Figure 5, has an arrangement where the first corner pixel PX31 is a light pixel and the remaining 8 pixels are dark pixels, and can detect the inner part of the processing target F1 located at a depth of 1 dot along the upper left edge of the downward-sloping left region AR4. The 3x3 pixel reference pattern P2, as shown in Figure 5, has an arrangement where the second corner pixel PX32 is a light pixel and the remaining 8 pixels are dark pixels, and can detect the inner part of the processing target F1 located at a depth of 1 dot along the upper right edge of the downward-sloping right region AR5. The 5x5 pixel reference pattern P21 has an arrangement where the first corner pixel PX31 and the two pixels adjacent to the first corner pixel PX31 are light pixels and the remaining 22 pixels are dark pixels, and can detect the inner part of the processing target F1 located at a depth of 2 dots along the upper left edge of the downward-sloping left region AR4. The 5x5 pixel reference pattern P22 has an arrangement where the second corner pixel PX32 and the two pixels adjacent to the second corner pixel PX32 are light pixels, and the remaining 22 pixels are dark pixels, making it possible to detect the inner part of the processing target F1 located at a depth of 2 dots along the upper right edge of the downward sloping region AR5. In the 5x5 pixel reference patterns P21 and P22, the pixel of interest PX1 and the pixels on both sides of the pixel of interest PX1 in the X and Y directions are dark pixels, so the cross region PX10 can be said to be in the dark region AR3. Note that in the example shown in Figure 11, "depth" refers to the depth in the X and Y directions.

[0079] For example, the controller 10 can sequentially set the target pixel PX1 from the image IM1 and perform pattern matching by applying the reference pattern P20 to the determination area centered on the target pixel PX1. Here, the controller 10 sets a 3x3 pixel determination area centered on the target pixel PX1 when applying reference patterns P1 and P2, and sets a 5x5 pixel determination area centered on the target pixel PX1 when applying reference patterns P21 and P22. With reference pattern P20, for the left-sloping area AR4 and the right-sloping area AR5, not only pixels that are 1 pixel away from the surrounding area AR2 in the first direction D1 or second direction D2, but also pixels that are 2 pixels away from the surrounding area AR2 in the first direction D1 or second direction D2 can become the inner area F1 to be processed.

[0080] Therefore, the depth of the inner part F1 of the detected processing target can be adjusted to the user's intent. Consequently, the print image quality is improved according to the user's intent.

[0081] Furthermore, in order to switch the detection target area AR1 in the print control process shown in Figure 3, the printing device 1 can display the object specification screen 580, exemplified in Figure 12A, on at least one of the output unit 25 of the operation panel 24 and the display device DU1 of the host device HO1. Figure 12A schematically shows an example of the display of the object specification screen 580. Figure 12B schematically illustrates the detection target area AR1 included in the image IM1.

[0082] The object specification screen 580 shown in Figure 12A includes multiple options for specifying the detection target area AR1, such as the "Text and Lines" item 281 and the "Entire Image" item 282. The "Text and Lines" item 281 is an option to make the detection target area AR1 consist of text and lines (including barcodes). Text and lines are examples of objects contained in image IM1. The "Entire Image" item 282 is an option to make the detection target area AR1 consist of the entire image IM1. For example, the controller 10 displays the object specification screen 580 on the output unit 25 and accepts the selection of one of the multiple options (281, 282) at the input unit 26 of the operation panel 24. If the controller 10 accepts the selection of the "Text and Lines" item 281, it extracts the text area AR1c and the line area AR1b from image IM1 as the detection target area AR1, as shown in Figure 12B. Image IM1 often has information indicating the position of text and lines associated with it. For example, if image IM1 originates from an image file containing information indicating the attributes of characters and lines, the controller 10 can obtain information indicating the positions of the characters and lines originating from the image file from the host device HO1 or the like. When the controller 10 receives a specification for the "whole" item 282, it treats the entire image IM1 as the detection target area AR1. Of course, the host device HO1 may also display the object specification screen 580 on the display device DU1 and accept the specification of one of several options (281, 282) at an input unit not shown. In either case, the object specification step ST6, in which objects included in image IM1 are specified, is performed. The controller 10 or host device HO1 performs detection processing to detect the inner part F1 and the edge part E1 of the specified objects as the detection target area AR1.

[0083] Therefore, the detection target area AR1 can be adjusted to the user's intent. Consequently, the print image quality is improved according to the user's intent. In particular, the effect of reducing the amount of ink in the processing target inner area F1 and processing target edge area E1 is significant for characters and lines (including barcodes). Furthermore, the object can consist of text only, or lines only.

[0084] (4) Variations: Various modifications of this invention are conceivable. For example, the combination of ink colors is not limited to C, M, Y, and K, and may include orange, green, light cyan at a lower concentration than C, light magenta at a lower concentration than M, dark yellow at a higher concentration than Y, light black at a lower concentration than K, etc. Of course, the embodiments of this application can also be applied when the printing apparatus 1 does not use any of the C, M, Y, and K inks.

[0085] Detection of the inner part F1 of the processing target is not limited to pattern matching. For example, the printing device 1 may, for each pixel PX0 of the 3x3 pixel determination area AD0, detect the pixel of interest PX1 as the inner part F1 of the processing target by confirming that the first corner pixel PX31 is a light pixel and the remaining 8 pixels are dark pixels, and then detect the pixel of interest PX1 as the inner part F1 of the processing target by confirming that the second corner pixel PX32 is a light pixel and the remaining 8 pixels are dark pixels.

[0086] The detection of the edge portion E1 to be processed is not limited to pattern matching. For example, the printing device 1 may detect a pixel of interest in the dark region AR3 whose filter calculation value using a horizontal Sobel filter is greater than or less than a predetermined threshold as the first edge portion E11. The printing device 1 may also detect a pixel of interest in the dark region AR3 whose filter calculation value using a vertical Sobel filter is greater than or less than a predetermined threshold as the second edge portion E12. Furthermore, the printing device 1 may detect the entire edge E0 in the dark region AR3 by filtering using a Laplacian filter, and then detect the edge portion E1 to be processed based on the position of a light pixel adjacent to the dark pixel at edge E0.

[0087] In the specific example described above, the inner and outer areas to be processed were detected from an RGB image, and the amount of ink in these areas was reduced. However, the method is not limited to this. For example, the control unit may detect the inner and outer areas to be processed from a CMYK image represented by ink amount data, and reduce the amount of ink in these areas. Alternatively, the control unit may generate corrected dot data by detecting the inner and outer areas to be processed from a dot image represented by uncorrected dot data, and then thinning or reducing the size of the dots in these areas.

[0088] (5) Conclusion: As described above, according to the present invention, in various embodiments, it is possible to provide a configuration that can suppress deterioration of diagonal edges in two diagonal directions while suppressing a decrease in print quality due to ink bleeding. Of course, even in embodiments consisting only of the constituent elements of the independent claims, the basic functions and effects described above can be obtained. Furthermore, configurations obtained by substituting or changing the combinations of each configuration disclosed in the above-mentioned examples, configurations obtained by substituting or changing the combinations of each configuration disclosed in the prior art and the above-mentioned examples, etc., are also possible. The present invention also includes these configurations, etc. [Explanation of Symbols]

[0089] 1...Printing device, 2...Printer, 10...Controller, 12...Edge correction unit, 30...Print head, 33...Nozzle row, 34...Nozzle, 36...Ink, 37...Ink droplet, 38...Dot, 50...Drive unit, 221..."Ink not ejected" item, 222..."Low ink ejection" item, 240...Selection, 241..."Black only" item, 242..."Other than white" item, 261..."Depth of 1 dot" item, 262..."Depth of 2 dots" item, 281..."Characters and lines" item, 282..."Overall" item, 520...Inner ink amount specification screen, 540...Dark area specification screen, 560...Edge depth specification screen, 580...Object specification screen, AD0...Judgment area, AR1...Detection target area, AR1b...Line area, AR1c...Character area, AR2...Surrounding area, AR3...Dark area, AR4...Left-downward sloping area, AR5...Right-downward sloping area, D1...First direction, D2...Second direction, DA1...Ink amount data, DA2...Dot data, DU1...Display device, E0...Edge, E1...Processing target edge part, E11...First edge part, E12...Second edge part, F1...Processing target inner part, HO1...Host device, IM1...Image, IM3...Corrected image, IM5...Printed image, ME0...Printing medium, P0, P1~P4, P10, P11~P15, P20, P21, P22...Reference pattern, PX0...Pixel, PX1...Pixel of interest, PX2...Adjacent pixel, PX3...Corner pixel, PX10...Cross region, PX31...First corner pixel, PX32...Second corner pixel, PX33...Third corner pixel, PX34...Fourth corner pixel, ST1...Detection process, ST2...Generation process, ST3...Printing process, ST4...Color specification process, ST5...Edge depth specification process, ST6...Object specification process, U1...Control unit.

Claims

1. A method for generating dot data that generates dot data indicating the position of dots formed by ink from a print head, An image having a plurality of pixels arranged in a first direction and a second direction perpendicular to the first direction includes a surrounding region and a denser region than the surrounding region. The aforementioned dot data generation method is: A detection step in which, if a rectangular determination area centered on a pixel of interest included in at least a portion of the detection target area of ​​the aforementioned image satisfies a predetermined edge-inside condition including the surrounding area and the dense area, the pixel of interest is detected as the inner part of the processing target, The process includes a generation step of generating dot data from the image such that the amount of ink ejected from the print head to the inner part of the object to be processed is reduced, The determination region includes a cross-shaped region within the determination region that includes the pixel of interest and the pixels adjacent to the pixel of interest in the first and second directions, and corner pixels at the four corners of the determination region. The corner pixels located at the four corners include a first corner pixel and a second corner pixel that is not diagonally opposite the first corner pixel in the determination area. In the detection step, In the determination region, if the first condition is met as the inner edge condition, where the cross region is in the dark region, the first corner pixel is in the surrounding region, and the three corner pixels excluding the first corner pixel are in the dark region, then the pixel of interest is detected as the inner part of the processing target. A dot data generation method in which, in the determination area, if the second condition is met as the inner edge condition, the cross region is in the dark region, the second corner pixel is in the surrounding region, and the three corner pixels excluding the second corner pixel are in the dark region, the pixel of interest is detected as the inner part of the processing target.

2. In the detection step, at least one of the edges present in the detection target area, namely a first edge portion located on one side of the dense region in the first direction and a second edge portion located on one side of the dense region in the second direction, is detected as the edge portion to be processed. The dot data generation method according to claim 1, wherein in the generation step, the dot data is generated from the image such that the amount of ink ejected from the print head to the edge portion to be processed is reduced.

3. The dot data generation method according to claim 2, wherein in the generation step, the amount of ink discharged from the print head to the edge portion of the object to be processed is less than the amount of ink discharged from the print head to the inner portion of the object to be processed.

4. The process further includes a color specification step of receiving a selection of options, including a predetermined color and a predetermined color range, to be applied to the dark area. In the detection step, When the predetermined color is specified, if the distribution of the dark area and the surrounding area in the determination area satisfies the edge inside condition, the pixel of interest is detected as the inner part of the processing target. The dot data generation method according to any one of claims 1 to 3, wherein, when the predetermined color range is specified, the distribution of the dark area and the surrounding area within the predetermined color range in the determination area satisfies the inner edge condition, and the pixel of interest is detected as the inner part of the processing target.

5. The process further includes an edge depth specification step that accepts the specification of the depth of the inner part of the object to be processed, The dot data generation method according to any one of claims 1 to 3, wherein the detection step involves detecting the inner portion of the object to be processed to a specified depth.

6. The process further includes an object specification step of specifying the objects included in the aforementioned image, The dot data generation method according to any one of claims 1 to 3, wherein in the detection step, the inner part of the processing target is detected with the region of the specified object as the detection target region.

7. A printing apparatus that forms a printed image on a printing medium using ink, A print head capable of ejecting the aforementioned ink, The system includes a control unit that controls the ejection of ink from the print head to the printing medium so that dots constituting the printed image are formed on the printing medium, An image having a plurality of pixels arranged in a first direction and a second direction perpendicular to the first direction includes a surrounding region and a denser region than the surrounding region. The control unit, A detection process in which, if a rectangular determination area centered on a pixel of interest included in at least a portion of the detection target area of ​​the aforementioned image satisfies a predetermined edge-inside condition including the surrounding area and the dense area, the pixel of interest is detected as the inner part of the processing target, Discharge control processing is performed to control the discharge of the ink from the print head to the printing medium so that the amount of ink discharged to the inner part of the object to be processed is reduced. The determination region includes a cross-shaped region within the determination region that includes the pixel of interest and the pixels adjacent to the pixel of interest in the first and second directions, and corner pixels at the four corners of the determination region. The corner pixels located at the four corners include a first corner pixel and a second corner pixel that is not diagonally opposite the first corner pixel in the determination area. In the detection process, the control unit, In the determination region, if the first condition is met as the inner edge condition, where the cross region is in the dark region, the first corner pixel is in the surrounding region, and the three corner pixels excluding the first corner pixel are in the dark region, then the pixel of interest is detected as the inner part of the processing target. A printing apparatus that detects the pixel of interest as the inner part of the processing target if, in the determination area, the cross region is in the dark region, the second corner pixel is in the surrounding region, and the three corner pixels excluding the second corner pixel are in the dark region, and these conditions are met as the inner edge condition.

Images