Image processing device, image processing method

Abstract

To provide a technology for determining necessity of movement of an image for printing, to a position where a defect that may occur due to a defective nozzle is hard to be conspicuous.SOLUTION: Necessity of movement of a printing position of an image for printing is determined on the basis of a feature amount of the image for printing and a feature amount of a density irregularity image by acquiring the density irregularity image in which density irregularity due to a nozzle in a nozzle array for discharging ink occurs in the image for printing.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an image processing technology for printing.

Background Art

[0002] A single-pass printing method that prints an image on printing paper by relatively scanning a recording head only once can print an image at a higher speed than a multi-pass printing method that prints an image by scanning the recording head multiple times with respect to the printing paper.

[0003] However, when the recording head is an inkjet recording head, ink ejection failure may occur due to the mixing of air bubbles into the nozzles of the inkjet recording head or clogging. In particular, in the single-pass printing method, this ejection failure is visually recognized as streak-like defects in the image on the printing paper in the direction of relative scanning. Therefore, conventionally, in an inkjet recording type printing apparatus, each time nozzle ejection failure is detected by a certain number of printed sheets or by a non-ejection inspection chart or the like, nozzle recovery operations such as nozzle density correction and head cleaning are performed. However, when such operations are performed, there is a problem that productivity decreases.

[0004] In Patent Document 1, in order to avoid the decrease in productivity associated with the nozzle recovery operation, when a defective ejection nozzle is detected, it is determined whether the paper can be moved and its posture changed to avoid it, and if it can be avoided, the frequency of the nozzle recovery operation is reduced by moving the image for printing. A method is disclosed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the method disclosed in Patent Document 1, in order to determine whether or not to move the print image to avoid using a defective nozzle, depending on the location of the detected defective nozzle, it may be difficult to move the print image, and the frequency of nozzle recovery operations may not be sufficiently reduced. The present invention provides a technique for determining whether or not it is necessary to move the print image to a position where defects that may be caused by a defective nozzle are less noticeable. [Means for solving the problem]

[0007] One aspect of the present invention is an acquisition means for acquiring a density unevenness image in a printed image caused by density unevenness in a nozzle row that ejects ink, A determination means for determining whether or not it is necessary to move the printing position of the printable image, based on the respective feature quantities of the printable image and the density unevenness image. 、 Notification means for notifying the result of the determination by the determination means and Equipped with, If the notification means determines that the printing position of the printable image can be moved, it notifies that the printer should stop the recovery operation of the defective nozzle until printing based on the print job is completed. It is characterized by the following: [Effects of the Invention]

[0008] According to the present invention, it is possible to determine whether or not it is necessary to move the printed image to a position where defects that may occur due to a faulty nozzle are less noticeable. [Brief explanation of the drawing]

[0009] [Figure 1] A block diagram showing an example of the hardware configuration of the image processing device 100. [Figure 2] A block diagram showing an example of the functional configuration of the image processing device 100. [Figure 3] A flowchart of the process performed by the image processing device 100 to determine whether and whether it is necessary to move the printing position of an image for printing. [Figure 4] A diagram showing examples of defects caused by a faulty nozzle in a printed image. [Figure 5] A diagram related to defective nozzle information. [Figure 6]Flowchart showing details of the process in step S303. [Figure 7] Diagram showing an example of a movable area. [Figure 8] Flowchart showing details of the process in step S306. [Figure 9] Diagram showing an example of notification of a determination result. [Figure 10] Diagram showing an example of a defective image. [Figure 11] Diagram showing an example of a VTF curve representing the spatial frequency response characteristics of vision. [Figure 12] Diagram showing an example of a defect occurring in a moved printed image. [Figure 13] Diagram showing an example of a defective image with the smallest difference Δ. [Figure 14] Flowchart showing details of the process in step S303. [Figure 15] Diagram showing an example of a defect caused by a printed image and a defective nozzle. [Figure 16] Flowchart showing details of the process in step S306. [Figure 17] Diagram showing an example of a defect occurring in a printed image with a changed surface attachment. [Figure 18] Diagram showing an example of a defective image with the smallest color difference ΔE. [Figure 19] Diagram showing an example of notification of a determination result. [Figure 20] Flowchart showing details of the process in step S307. [Figure 21] Diagram showing an example of notification of a determination result. [Figure 22] Flowchart showing details of the process in step S306. [Figure 23] Diagram showing an example of a defect caused by a printed image and a defective nozzle. [Figure 24] Diagram showing an example of a defect occurring in a moved printed image. [Figure 25] Diagram showing an example of a defective image with less prominent defects on both sides.

Mode for Carrying Out the Invention

[0010] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention to the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, the same or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0011] [First Embodiment] This embodiment describes an image processing device that determines whether or not it is necessary or possible to move a printable image to a printing position where defects caused by faulty nozzles in the nozzle row used for printing the printable image are less noticeable, based on the "visual frequency response characteristics" of the printable image.

[0012] First, an example of the hardware configuration of the image processing device 100 according to this embodiment will be explained using the block diagram in Figure 1. The image processing device 100 according to this embodiment can be a computer device such as a PC (personal computer), a tablet terminal, or a smartphone.

[0013] The input unit 101 is a serial bus interface such as USB, and user interfaces such as a keyboard and mouse can be connected to it. Additionally, image input devices such as memory card readers, digital cameras, and scanners can also be connected to the input unit 101.

[0014] The display unit 102 has an LCD screen or a touch panel screen and can display the processing results of the CPU 104 as images, text, etc. The display unit 102 may also be a projection device such as a projector that projects images and text.

[0015] The memory unit 103 is a large-capacity information storage device such as a hard disk drive (HDD) or a solid-state drive (SSD). The memory unit 103 stores the OS (operating system), computer programs and data that cause the CPU 104 to execute or control various processes described as being performed by the image processing device 100. The computer programs and data stored in the memory unit 103 are loaded into the RAM 106 as appropriate according to the control of the CPU 104 and become the target of processing by the CPU 104.

[0016] The output unit 108 is a serial bus interface such as USB, and outputs various types of data, such as print data and images, to devices connected to the serial bus, such as a printer 111 and a memory card writer.

[0017] The CPU 104 executes various processes using computer programs and data stored in the ROM 105 and RAM 106. In doing so, the CPU 104 controls the overall operation of the image processing device 100 and executes or controls the various processes described as being performed by the image processing device 100.

[0018] ROM 105 stores configuration data for the image processing device 100, computer programs and data related to the startup of the image processing device 100, computer programs and data related to the basic operation of the image processing device 100, and so on.

[0019] RAM 106 has areas for storing computer programs and data loaded from memory unit 103 and ROM 105, and areas for storing data received from the outside via input unit 101. RAM 106 also has areas for storing data received from the outside via communication unit 107, and a work area used by CPU 104 when executing various processes. In this way, RAM 106 can provide various areas as needed.

[0020] The communication unit 107 is a network interface for connecting to a wired or wireless network 110, such as Wi-Fi or P2P. The CPU 104 can communicate with server devices and other computer equipment on the network 110 via the communication unit 107. The CPU 104 can receive various computer programs and data from server devices and other computer equipment on the network 110, execute processing, and provide processing results to server devices and other computer equipment on the network 110. The printing device 111 is also among the devices with which the CPU 104 can communicate via the communication unit 107, and various types of data can be sent to the printing device 111 via the communication unit 107.

[0021] Furthermore, if a tablet device or smartphone is used as the image processing device 100, the display unit 102 may have a touchscreen function, in which case the display unit 102 also functions as an input unit 101 for receiving user instructions.

[0022] An example of the functional configuration of the image processing device 100 is shown in the block diagram of Figure 2. In this embodiment, the case in which each functional unit shown in Figure 2 is implemented by a computer program will be described. In the following, the functional units shown in Figure 2 may be described as the main processing units, but in reality, the CPU 104 executes the computer program corresponding to the functional unit to realize the function of that functional unit. Note that one or more of the functional units shown in Figure 2 may be implemented in hardware.

[0023] The process performed by the image processing device 100 according to this embodiment to determine whether or not it is necessary and possible to move the printing position of the printable image will be explained with reference to the flowchart in Figure 3.

[0024] In step S301, the input unit 201 acquires a printable image. The method and source of acquiring the printable image are not limited to a specific method or source. For example, a printable image stored in the memory unit 103 may be acquired into the RAM 106, or a printable image received from an external source via the input unit 101 or the communication unit 107 may be acquired into the RAM 106. The following describes a case in which the input unit 201 acquires the printable image shown in Figure 4(a). The printable image shown in Figure 4(a) is an image that includes a subject (tree) 401 having a high-frequency texture and a subject (ground) 402 having a low-frequency texture.

[0025] Here, Figure 4(b) shows an example of an image (printed image) printed on a recording medium such as paper by the printing device 111 based on the printable image in Figure 4(a). The recording head of the printing device 111 has a nozzle row 403 arranged in the X direction (a direction perpendicular to the transport direction of the recording medium) (i.e., the X direction is the direction in which the nozzle row 403 is arranged), and when the recording medium is transported in the Y direction (the transport direction of the recording medium), ink is dropped onto the recording medium from the nozzle row 403, thereby printing an image on the recording medium. In this embodiment, as shown in Figure 4(b), a nozzle row 404 arranged in a continuous position in the nozzle row 403 is a defective nozzle (a nozzle that causes ejection failure due to the inclusion of air bubbles or clogging in the nozzle), resulting in streaky density unevenness 405 in the printed image on the recording medium, with the width of the nozzle row 404 in the X direction and extending across the entire printed image in the Y direction.

[0026] In step S302, the input unit 202 acquires defective nozzle information, which associates the location of a defective nozzle in the nozzle row of the printing device 111 with the amount of density change at that defective nozzle. The method and source of acquiring the defective nozzle information are not limited to a specific method or source. For example, defective nozzle information stored in the storage unit 103 may be acquired into the RAM 106, or defective nozzle information received from an external source via the input unit 101 or the communication unit 107 may be acquired into the RAM 106.

[0027] Defective nozzle information is generated, for example, as follows. First, an image containing multiple patches of different tonal values ​​(tone patches), as exemplified in Figure 5(a), or an image containing a non-discharge inspection pattern chart, as shown in Figure 5(b), is used as an inspection image, and the printing device 111 prints the inspection image onto a recording medium. Then, a scanned image is obtained by scanning the recording medium on which the inspection image has been printed. The image processing device 100 then calculates the density change amount for each nozzle in the nozzle row by multiplying the average value of the density ratio = (density value at that position in the scanned image) / (density value at that position in the inspection image), which is obtained for each position corresponding to the nozzle in the scanned image, by 100. The density change amount is calculated for each color component (for example, for each of C, M, Y, and K), but in this embodiment, for simplicity of explanation, one color component will be described. The image processing device 100 then identifies nozzles in the nozzle row whose density change amount is below a threshold as defective nozzles, and registers the position and density change amount of the defective nozzles as defective nozzle information.

[0028] Figure 5(c) shows an example of the relationship between the position (nozzle number) of each nozzle in a nozzle row and the amount of density change of that nozzle. In Figure 5(c), the amount of density change of a nozzle is the average value of (XY) / Y for each position corresponding to the nozzle, multiplied by 100, where X = (density value at the position corresponding to the nozzle in the reading image) and Y = (density value at the position corresponding to the nozzle in the inspection image). In the case of Figure 5(c), the nozzles whose absolute value of the amount of density change is below the threshold (nozzles with low-frequency density changes where the density changes slightly) are nozzles with nozzle numbers 4500 to 4510. Therefore, nozzles with nozzle numbers 4500 to 4510 are considered defective nozzles. Thus, in this case, defective nozzle information is obtained that retains the position of the defective nozzle (nozzle number: 4500 to 4510) and the amount of density change of the defective nozzle.

[0029] Furthermore, the criteria for determining which nozzles are defective in a nozzle row, the method for generating defective nozzle information, and the device for generating defective nozzle information are not limited to a specific form; it is sufficient to obtain defective nozzle information that can identify the location of the defective nozzle and the amount of concentration change.

[0030] Returning to Figure 3, in step S303, the determination unit 203 determines whether or not it is necessary to move the printing position of the print image based on the print image acquired in step S301 and the defective nozzle information acquired in step S302. Details of the process in step S303 will be explained with reference to Figure 6.

[0031] If, as a result of this determination, it is determined that the print position of the image needs to be moved, the process proceeds to step S305 via step S304. On the other hand, if it is determined that the print position of the image does not need to be moved (it is unnecessary), the process proceeds to step S307 via step S304.

[0032] In step S305, the calculation unit 204 identifies the margin areas on the recording medium (areas on the recording medium where the print image is not printed) as movable areas based on the print settings for the print image. In this embodiment, as shown in Figure 7, the calculation unit 204 identifies the following as movable areas based on the print settings for the print image: a margin area of ​​width yu (pixels) from the top edge of the recording medium, a margin area of ​​width yb (pixels) from the bottom edge of the recording medium, a margin area of ​​width xl (pixels) from the left edge of the recording medium, and a margin area of ​​width xr (pixels) from the right edge of the recording medium.

[0033] In step S306, the determination unit 205 determines whether the printing position of the print image within the movable area can be moved, based on the print image acquired in step S301 and the defective nozzle information acquired in step S302. Details of the process in step S306 will be explained with reference to Figure 8.

[0034] In step S307, the notification unit 206 notifies the user of the results of the determinations made in steps S303 and S306. For example, as shown in Figure 9, the notification unit 206 displays a screen on the display unit 102 that includes the nozzle numbers of the defective nozzles "4500-4510", the information "Need" indicating that the print position of the print image needs to be moved, and the information "OK" indicating that the print position of the print image can be moved. The content and format of the display are not limited to a specific format. In addition to or instead of such a display, the notification unit 206 may output the results of the determinations made in steps S303 and S306 to the printing device 111 and print the results of the determinations made in steps S303 and S306 onto a recording medium. Alternatively, in addition to or instead of these notifications, the notification unit 206 may transmit the results of the determinations made in steps S303 and S306 to an external device via the communication unit 107.

[0035] Next, the details of the process in step S303 described above will be explained according to the flowchart in Figure 6. In step S601, the determination unit 203 generates a defective image by changing the pixel value (density value) of the corresponding pixel position on the print image corresponding to the position of each defective nozzle included in the defective nozzle information, according to the amount of density change of the defective nozzle included in the defective nozzle information.

[0036] As a result, for example as shown in Figure 10, a defective image is generated in which the width in the X direction is the width of the nozzle row 404 which is a defective nozzle, and the Y direction has streaky density unevenness 405 that extends across the entire print image.

[0037] In step S602, the determination unit 203 performs VisualTransferFunction (VTF) filtering on both the print image and the defective image. VTF filtering is a process for detection based on the frequency response characteristics of vision. Figure 11 shows a VTF curve representing the known spatial frequency response characteristics of vision, as proposed by Dooley et al. The vertical axis represents spatial frequency response intensity, and the horizontal axis represents spatial frequency (cycle / pixel). It exhibits a bandpass filter type spatial frequency response characteristic where contrast is most easily perceived at spatial frequencies around 1.5 cycles / pixel. In this embodiment, by performing VTF filtering on both the print image and the defective image, the visibility of defects is evaluated based on the frequency response characteristics of vision.

[0038] In this way, the determination unit 203 acquires the visual frequency response characteristics of the printable image as the visual feature quantity (visual feature quantity) of the printable image, and acquires the visual frequency response characteristics of the defective image as the visual feature quantity of the defective image.

[0039] In step S603, the determination unit 203 generates a difference image between the printable image (image P) that has undergone VTF filtering and the defective image (image Q) that has undergone VTF filtering. The pixel value at pixel position (x, y) in the difference image is, for example, the absolute difference between the pixel value at pixel position (x, y) in image P and the pixel value at pixel position (x, y) in image Q. The determination unit 203 then calculates the sum of the pixel values ​​of all pixels in the difference image as the difference Δ.

[0040] In step S604, the determination unit 203 determines whether Δ>Δth is satisfied. Δth is a predetermined threshold, and in this embodiment, for example, Δth=10. If the result of this determination is that Δ>Δth is satisfied, the process proceeds to step S605; otherwise, the process proceeds to step S606.

[0041] In step S605, the determination unit 203 determines that it is necessary to move the print image so that the defects caused by the faulty nozzle are not noticeable, and stores the necessity result information indicating the result of this determination in the RAM 106 or the storage unit 103.

[0042] In step S606, the determination unit 203 determines that it is not necessary (unnecessary) to move the print image in order to make the defects caused by the faulty nozzle less noticeable, and stores the necessity result information indicating the result of this determination in the RAM 106 or the storage unit 103.

[0043] Next, the details of the process in step S306 described above will be explained according to the flowchart in Figure 8. The processes in steps S801 to S805 are performed on the printable image that has been moved to each position at an interval of Δx between the left edge and the right edge of the recording medium, so as not to extend beyond the recording medium. Here, the initial value of the variable n is assumed to be 2.

[0044] In step S802, the determination unit 205 places the print image at a position moved by nΔx in the X direction from the "print position of the print image on the recording medium" indicated by the print settings, and generates a defective image by changing the pixel value of the corresponding position on the print image corresponding to the position of the defective nozzle indicated by the defective nozzle information, according to the amount of density change of the defective nozzle indicated by the defective nozzle information. For example, the right edge of the print image placed at a position moved by 2Δx in the X direction from the "print position of the print image on the recording medium" indicated by the print settings coincides with or is close to the right edge of the recording medium.

[0045] In step S803, the determination unit 205 performs VTF filtering on both the print image and the defective image generated in step S802. In step S804, similar to step S603 above, the determination unit 205 generates a difference image between the print image that has undergone VTF filtering and the defective image that has undergone VTF filtering, and calculates the difference Δ as the sum of the pixel values ​​of all pixels in the difference image.

[0046] The determination unit 205 then decrements the value of variable n by one. If the result is greater than -3, the process proceeds to step S802. If the value of variable n is equal to -3, the process proceeds to step S806. In other words, the processes in steps S801 to S805 are performed for values ​​of variable n = 2, 1, 0, -1, and -2. For example, the left edge of a print image placed at a position moved by -2Δx in the X direction from the "print position of the print image on the recording medium" indicated by the print settings coincides with or is close to the left edge of the recording medium. Note that Δx indicates the movement interval of the print image and can be changed arbitrarily, in which case the range of possible values ​​for variable n can also be changed accordingly.

[0047] The defective image obtained in this way will be explained using Figure 12. When the position of the print image is moved as described above, the position corresponding to the defective nozzle in the print image changes. As shown in Figure 12, when the print image moves 2Δx, Δx, ..., -2Δx in the X direction due to the relative movement between the nozzle row 403 and the print image, the streaky density unevenness 405 in the print image will move -2Δx, -Δx, ..., 2Δx in the X direction, resulting in the generation of defective images in which the density unevenness 405 is assigned to different positions.

[0048] In step S806, the determination unit 205 identifies the smallest difference Δ (Δmin) among the differences Δ obtained in the processing steps S801 to S805. In this embodiment, among the group of defective images generated in the processing steps S801 to S805, the smallest difference Δ is determined to be in the defective image shown in Figure 13, where the print image has moved -2Δx in the X direction, i.e., where density unevenness 405 is applied at a position moved 2Δx in the X direction. Low-frequency streaky density unevenness 405, which has the width of the nozzle row 404 in the X direction and is caused by a poor ink ejection of the nozzle row 404, is less noticeable on the subject 401 which has a high-frequency texture on the right side of the print image, and therefore the difference Δ is minimized.

[0049] In step S807, the determination unit 205 determines whether Δmin < Δth is satisfied. Δth may be the same as or different from the previous Δth. If the result of this determination is that Δmin < Δth is satisfied, the process proceeds to step S808; otherwise, the process proceeds to step S809.

[0050] In step S808, the determination unit 205 determines that it is possible to move the printable image in a way that does not cause defects due to the faulty nozzle, and stores the result of this determination, the placement position of the printable image corresponding to Δmin, and the feasibility result information in the RAM 106 or storage unit 103.

[0051] In step S809, the determination unit 205 determines that it is impossible to move a print image in which defects caused by a faulty nozzle are not noticeable, and stores the result of this determination, such as pass / fail information, in the RAM 106 or storage unit 103.

[0052] Thus, according to this embodiment, it is possible to inform the user whether it is necessary and possible to move the printed image to a position where defects caused by faulty nozzles are less noticeable, based on the visual frequency response characteristics of the printed image.

[0053] <Variation> In this embodiment, defective nozzle information, including the location of the defective nozzle and the amount of density change, is obtained from a chart print image such as a grayscale patch, and a defective image is generated based on this defective nozzle information. However, the defective image is not limited to those generated in this way; for example, a defective image may be obtained by an inspection process that compares the print image to be inspected with an inspection reference image that serves as the basis for inspection. In other words, the method for obtaining a defective image is not limited to a specific method.

[0054] Furthermore, in this embodiment, a VTF filter was used to evaluate the visibility of defects, but this could be replaced with an MTF filter or Gaussian filter of a scanner used to scan printed images, or a combination of these.

[0055] Furthermore, in this embodiment, it was determined whether or not the printing position of the printable image needed to be moved for single-sided printing. In the case of double-sided printing, if it is determined that "movement of the printing position is necessary" for either the front or back side, it may be determined that "movement of the printing position is necessary" for both the front and back sides.

[0056] [Second Embodiment] In the following embodiments, including this embodiment, the differences from the first embodiment will be described, and unless otherwise specified below, they will be the same as the first embodiment. In the first embodiment, a method for determining whether it is necessary and possible to move a print image to a position where defects caused by a defective nozzle are less noticeable was described based on the visual frequency response characteristics of the print image. In contrast, in this embodiment, a method for determining whether it is necessary and possible to move a print image to a position where defects caused by a defective nozzle are less noticeable will be described based on the visual color response characteristics.

[0057] In this embodiment, the process in step S303 described above is carried out according to the flowchart in Figure 14. In Figure 14, the same processing steps as in Figure 6 are given the same step numbers, and the explanation of these processing steps is omitted or only briefly explained.

[0058] In this embodiment, in step S301, a printable image is obtained as an image for printing, as exemplified in Figure 15(a). In the printable image shown in Figure 15(a), a solid black image 1502 is placed in the left region, and a solid yellow image 1501 is placed in the right region.

[0059] When the printable image in Figure 15(a) is printed onto a recording medium by the printing device 111 (borderless printing), one of the nozzles 1503 that ejects yellow ink in the nozzle row 403 fails to eject ink. As shown in Figure 15(b), a thin, linear streak of non-ejection 1504 appears on the printed image (the image printed on the recording medium based on the printable image in Figure 15(a)), with the width of the nozzle 1503 in the X direction and extending across the entire printed image in the Y direction. Such a printed image is a defective image. In this embodiment, in step S601, the determination unit 203 generates a defective image from such a printed image in the same manner as in the first embodiment.

[0060] In step S1401, the determination unit 203 converts the pixel values ​​(RGB values) of pixels in the printable image (image P) that has undergone VTF filtering into L*a*b* values ​​using a known RGB-L*a*b* color space conversion. Similarly, the determination unit 203 converts the pixel values ​​(RGB values) of pixels in the defective image (image Q) that has undergone VTF filtering into L*a*b* values ​​using a known RGB-L*a*b* color space conversion. The determination unit 203 then generates a difference image between image P, which has undergone RGB-L*a*b* color space conversion, and image Q, which has undergone RGB-L*a*b* color space conversion, in the same manner as in the first embodiment, and calculates the sum of the pixel values ​​of all pixels in the generated difference image as the color difference ΔE.

[0061] In the example in Figure 15, the RGB values ​​of the solid yellow image 1501 in the right region of the print image are (R,G,B)=(230,230,160) and the L*a*b* values ​​are (L*,a*,b*)=(89.8,-10.6,34.2). Also, the RGB values ​​of the solid black image 1502 in the left region of the print image are (R,G,B)=(48,48,48) and the L*a*b* values ​​are (L*,a*,b*)=(19.9,0,0). In Figure 15(b), the RGB values ​​of the non-spitting streak 1504 added to the defective image are (R,G,B)=(48,48,67) and the L*a*b* values ​​are (L*,a*,b*)=(20.6,5.1,-11.9). As shown in Figure 15(b), the RGB difference Δ=19 and the color difference ΔE=13 between the solid image 1502 and the non-discharged streaks 1504 in the black area on the left side of the defective image. In this embodiment, by calculating the color difference ΔE between the printable image and the defective image, the visibility of the defect can be evaluated based on the color response characteristics of the eye.

[0062] Returning to Figure 14, in step S1402, the determination unit 203 determines whether ΔE > Δth is satisfied. Δth may be the same as the previous Δth, or it may be different. In this embodiment, for example, Δth = 10. If the result of this determination is that ΔE > Δth is satisfied, the process proceeds to step S605; otherwise, the process proceeds to step S606.

[0063] In this embodiment, step S306 is performed according to the flowchart in Figure 16. In Figure 16, the same processing steps as in Figure 8 are given the same step numbers, and the explanation of these processing steps is omitted or only briefly explained.

[0064] In this embodiment, in order to print the print image shown in Figure 15(a) without borders, in step S305, the calculation unit 204 acquires the rotation angles for rotating the print image by 0°, 90°, 180°, and 270° as movable regions. Therefore, in this embodiment, the processing in steps S801 to S805 is performed on the print image rotated by each of the rotation angles of 0°, 90°, 180°, and 270°.

[0065] Therefore, in step S802, a defective image is generated, as shown in Figures 17(a) to (d), in which a fine line-like streak 1504 is added to the print image that has been repositioned by rotations of 0°, 90°, 180°, and 270°, due to the failure of the nozzle 1503 that ejects yellow ink.

[0066] More specifically, the determination unit 205 generates a defective image corresponding to the 0° rotated (unrotated) print image by changing the pixel value (density value) of the corresponding pixel position on the print image (print image rotated 0° (unrotated)) corresponding to the position of each defective nozzle included in the defective nozzle information, according to the amount of density change of the defective nozzle included in the defective nozzle information.

[0067] Furthermore, the determination unit 205 generates a defective image corresponding to the 90° rotated print image by changing the pixel value (density value) of the corresponding pixel position on the print image (print image rotated 90°) corresponding to the position of each defective nozzle included in the defective nozzle information, according to the amount of density change of the defective nozzle included in the defective nozzle information.

[0068] Furthermore, the determination unit 205 generates a defect image corresponding to the 180° rotated print image by changing the pixel value (density value) of the corresponding pixel position on the print image (print image rotated 180°) corresponding to the position of each defective nozzle included in the defective nozzle information, according to the amount of density change of the defective nozzle included in the defective nozzle information.

[0069] Furthermore, the determination unit 205 generates a defective image corresponding to the 270° rotated print image, by changing the pixel value (density value) of the corresponding pixel position on the print image (270° rotated print image) corresponding to the position of each defective nozzle included in the defective nozzle information, according to the amount of density change of the defective nozzle included in the defective nozzle information.

[0070] In step S1601, the determination unit 205 converts the pixel values ​​(RGB values) of pixels in the print image (image P) that has undergone VTF filtering into L*a*b* values, similar to step S1401 above. Similarly, the determination unit 203 converts the pixel values ​​(RGB values) of pixels in the defective image (image Q) that has undergone VTF filtering into L*a*b* values.

[0071] In this way, the determination unit 203 acquires the visual color response characteristics of the printable image as a visual feature of the printable image, and acquires the visual color response characteristics of the defective image as a visual feature of the defective image.

[0072] The determination unit 203 then generates a difference image between the image P that has undergone RGB-L*a*b* color space conversion and the image Q that has undergone RGB-L*a*b* color space conversion, in the same manner as in the first embodiment, and calculates the sum of the pixel values ​​of all pixels in the generated difference image as the color difference ΔE.

[0073] As shown in Figure 17(a), the RGB values ​​of the non-spitting streaks 1504 applied to a solid black image in a print image rotated 0° are (R,G,B)=(48,48,67), and the L*a*b* values ​​are (L*,a*,b*)=(20.6,5.1,-11.9). As shown in Figure 17(c), the RGB values ​​of the non-spitting streaks 1504 applied to a solid yellow image in a print image rotated 180° are (R,G,B)=(230,230,179), and the L*a*b* values ​​are (L*,a*,b*)=(90.2,-8.1,24.9). As shown in Figure 17(a), the RGB difference Δ=19 and the color difference ΔE=13 between the solid black image and the non-spitting streaks 1504 in a print image rotated 0°. Furthermore, as shown in Figure 17(c), the RGB difference Δ=19 and the color difference ΔE=9.6 between the solid yellow image and the non-striped 1504 in the 180° rotated print image.

[0074] In this embodiment, by calculating the color difference ΔE between the printable image and the defective image, it is possible to evaluate the visibility of defects based on the visual color response characteristics, even among defective images with the same RGB difference Δ as shown in Figures 17(a) and (c).

[0075] In step S1602, the determination unit 205 identifies the smallest difference Δ(ΔEmin) among the color differences ΔE obtained in steps S801 to S805. In this embodiment, among the group of defective images generated in steps S801 to S805, the defective image shown in Figure 18, in which a non-discharge streak 1504 is added to a printable image rotated 180°, is considered to have the smallest difference ΔE.

[0076] The fine, linear streaks 1504 caused by the failure of the nozzle 1503 to eject yellow ink are less noticeable on the solid yellow image 1501 in the right-hand region of the printed image, resulting in a minimum color difference ΔE.

[0077] In step S1603, the determination unit 205 determines whether ΔEmin < ΔEth is satisfied. ΔEth may be the same as or different from the previous Δth. If the result of this determination is that ΔEmin < ΔEth is satisfied, the process proceeds to step S808; otherwise, the process proceeds to step S809.

[0078] In this embodiment, the notification unit 206 causes the display unit 102 to display a screen including, for example, the nozzle number of the defective nozzle "4500", information indicating that the printing position of the printable image needs to be moved "Need", information indicating that the mode for translating the printing position of the printable image is not as in the first embodiment "NG", information indicating the rotation angle of the printable image "180°", and information indicating that rotation of the printable image is possible "OK".

[0079] Thus, according to this embodiment, it is possible to notify the user whether it is necessary and possible to move the print image to a printing position where defects caused by faulty nozzles are less noticeable, based on the visual color response characteristics.

[0080] [Third Embodiment] In the first and second embodiments, a method was described for notifying whether it is necessary and possible to move the print image to a printing position where defects caused by faulty nozzles are less noticeable, based on visual characteristics. In this embodiment, if it is determined that the print image can be moved, the printer is notified to stop the faulty nozzle recovery operation until printing based on the print job is completed, thereby avoiding the generation of new faulty nozzles associated with the recovery operation and reducing the frequency of the recovery operation.

[0081] In this embodiment, step S307 is performed according to the flowchart in Figure 20. In step S2001, the notification unit 206 refers to the approval / rejection result information stored in the RAM 106 and the storage unit 103 and determines whether the approval / rejection result information indicates that the printable image can be moved. If the result of this determination indicates that the printable image can be moved, the process proceeds to step S2002; if the approval / rejection result information indicates that the printable image cannot be moved, the process proceeds to step S2003.

[0082] In step S2002, the notification unit 206 displays a screen on the display unit 211 containing various information, including a value for a stop flag indicating that the recovery operation will be stopped until the print job is completed. For example, as shown in Figure 21(a), the notification unit 206 displays a screen on the display unit 102 containing the nozzle numbers of the defective nozzles "4500-4510", information indicating that the print position of the print image needs to be moved "Need", information indicating that the print position of the print image is not in a mode of parallel movement as in the first embodiment "NG", information indicating the rotation angle of the print image "180°", information indicating that the print image can be rotated "OK", and the value of the stop flag indicating that the recovery operation will be stopped until the print job is completed "Pause until job is done".

[0083] In step S2003, the notification unit 206 displays a screen on the display unit 211 containing various information, including a value for a stop flag indicating that the recovery operation will not be stopped until the print job is completed. For example, as shown in Figure 21(b), the notification unit 206 displays a screen on the display unit 102 containing the nozzle numbers of the defective nozzles "4500-4510", information indicating that the print position of the print image needs to be moved "Need", information indicating that the mode for translating the print position of the print image is not as in the first embodiment "NG", information indicating that rotation of the print image is not possible "NG", and the value for a stop flag indicating that the recovery operation will not be stopped until the print job is completed "Active".

[0084] In this embodiment as well, the method of notifying various types of information, including the value of the stop flag, is not limited to a specific notification method, nor is the information to be notified limited to the examples shown in Figures 21(a) and (b).

[0085] Furthermore, the image processing device 100 may notify the printing device 111 of such a stop flag, causing the printing device 111 to control the execution of a recovery operation according to the value of the stop flag. In this way, according to this embodiment, it is possible to avoid the occurrence of new defective nozzles associated with the recovery operation and to reduce the frequency of the recovery operation.

[0086] [Fourth Embodiment] In this embodiment, even when a printing device prints a printable image on both sides of a recording medium, a method for determining whether or not a printable image can be moved is described based on visual features calculated for the printable images on both sides.

[0087] In this embodiment, in step S301, a front print image, as illustrated in Figure 23(a), is obtained as a print image to be printed on the front surface of the recording medium, and a back print image, as illustrated in Figure 23(b), is obtained as a print image to be printed on the back surface of the recording medium.

[0088] The image for front printing shown in Figure 23(a) is the same as the image for printing shown in Figure 4(a). The image for back printing shown in Figure 23(b) is an image in which the right-hand area is a blank area (white paper) and the left-hand area is the area where the string "2301" is placed.

[0089] Figure 23(c) shows an example of an image (printed image) printed on the surface of a recording medium by the printing device 111 based on the surface printing image in Figure 23(a). In this embodiment, as shown in Figure 23(c), due to a defective nozzle in nozzle row 404 which is located in a continuous position in nozzle row 403, streaky density unevenness 405 occurs in the printed image printed on the surface of the recording medium, with the width of nozzle row 404 in the X direction and extending across the entire printed image in the Y direction.

[0090] Figure 23(d) shows an example of an image (printed image) printed on the back surface of a recording medium by the printing device 111 based on the image for back surface printing in Figure 23(b). In this embodiment, as shown in Figure 23(d), due to a defective nozzle in nozzle row 404 which is located in a continuous position in nozzle row 403, streaky density unevenness 2302 occurs in the printed image printed on the back surface of the recording medium, with the width of nozzle row 404 in the X direction and extending across the entire printed image in the Y direction.

[0091] Then, the process of step S303 described in the first embodiment is performed for both the image for front printing and the image for back printing. If it is determined that a movement of the printing position is necessary for at least one of the image for front printing and the image for back printing, the process proceeds to step S305 via step S304. On the other hand, if it is determined that a movement of the printing position of the images is not necessary (unnecessary) for both the image for front printing and the image for back printing, the process proceeds to step S307 via step S304. If it is determined that a movement of the printing position is necessary for both the image for front printing and the image for back printing, the process may proceed to step S305 via step S304.

[0092] In this embodiment, step S306 is performed according to the flowchart in Figure 22. In Figure 22, the same processing steps as in Figure 8 are given the same step numbers, and the explanation of these processing steps is omitted or simplified.

[0093] In this embodiment, in step S802, the determination unit 205 generates defect images for each of the surface printable image and the back printable image in the same manner as in the first embodiment. The defect images obtained in this manner will be explained with reference to Figure 24.

[0094] As shown in Figure 24(a), with respect to the defect image generated from the surface printing image, when the surface printing image moves 2Δx, Δx, ..., -2Δx in the X direction due to the relative movement between the nozzle row 403 and the surface printing image, the streaky density unevenness 405 in the surface printing image will move -2Δx, -Δx, ..., 2Δx in the X direction, resulting in the generation of defect images with density unevenness 405 at different positions.

[0095] As shown in Figure 24(b), with respect to the defect image generated from the reverse side printing image, when the reverse side printing image moves 2Δx, Δx, ..., -2Δx in the X direction due to the relative movement between the nozzle row 403 and the reverse side printing image, the streaky density unevenness 405 in the reverse side printing image will move -2Δx, -Δx, ..., 2Δx in the X direction, resulting in the generation of defect images with density unevenness 2302 at different positions.

[0096] In this embodiment, in step S803, the determination unit 205 performs VTF filtering on the front print image, the back print image, and the defective image generated in step S802.

[0097] In step S2201, the determination unit 205 generates a difference image between the VTF-filtered image for front printing and the VTF-filtered defective image (defective image generated from the front printing image), and calculates the sum of the pixel values ​​of all pixels in the difference image as the difference Δf. The determination unit 205 also generates a difference image between the VTF-filtered image for back printing and the VTF-filtered defective image (defective image generated from the back printing image), and calculates the sum of the pixel values ​​of all pixels in the difference image as the difference Δb.

[0098] In step S2202, the determination unit 205 determines whether the difference Δf and the difference Δb satisfy Max(Δf, Δb) < Δth. Max(a, b) is a function that returns the larger of a and b. Also, Δth may be the same as or different from the above Δth.

[0099] If the result of this determination shows that the differences Δf and Δb satisfy Max(Δf,Δb)<Δth', the process proceeds to step S2203. On the other hand, if the differences Δf and Δb do not satisfy Max(Δf,Δb)<Δth', the process proceeds to step S802 if the value of variable n is greater than -3, and to step S2204 if the value of variable n is equal to -3.

[0100] In step S2203, the determination unit 205 calculates Δs = Δf + Δb and stores the resulting Δs in the RAM 106 or storage unit 103. In step S2204, the determination unit 205 determines whether at least one Δs is stored in the RAM 106 or storage unit 103, that is, whether or not a defective image for which Δs was calculated exists. If, as a result of this determination, at least one Δs is stored in the RAM 106 or storage unit 103 (a defective image for which Δs was calculated exists), it is determined that both the front-printing image and the back-printing image, where defects caused by the faulty nozzle are not noticeable, can be moved, and the process proceeds to step S2205. On the other hand, if no Δs are stored in the RAM 106 or storage unit 103 (no defective image for which Δs was calculated exists), the process proceeds to step S809.

[0101] In step S2205, the determination unit 205 identifies the smallest Δs (Δsmin) among the Δs stored in the RAM 106 and the storage unit 103. In this embodiment, among the group of defective images generated in steps S801 to S805, the defect image shown in Figure 25, in which the difference Δs is smallest when the front printing image and the back printing image are moved -2Δx in the X direction, i.e., when density unevenness is applied at a position moved 2Δx in the X direction, is considered to be the one with the smallest difference Δs. Figure 25(a) shows the defective image with the smallest Δs among the group of defective images generated from the front printing image, and Figure 25(b) shows the defective image with the smallest Δs among the group of defective images generated from the back printing image.

[0102] As shown in Figure 25(a), the low-frequency streaky density unevenness 405, which has the width of the nozzle row 404 in the X direction and is caused by poor ink ejection of the nozzle row 404, is not very noticeable on the subject 401, which has a high-frequency texture to the right of the image printed on the front side. Also, as shown in Figure 25(b), the low-frequency streaky density unevenness, which has the width of the nozzle row 404 in the X direction and is caused by poor ink ejection of the nozzle row 404, is not very noticeable on the blank area to the right of the image printed on the back side. As a result, Δs, which is the sum of Δf corresponding to the image printed on the front side and Δb corresponding to the image printed on the back side, is equal to Δsmin.

[0103] Thus, according to this embodiment, even when a printing device prints an image on both sides of a recording medium, the user can be notified whether it is necessary and possible to move the print image to a position where defects caused by faulty nozzles are less noticeable, based on the visual feature quantities calculated for the print images on both sides.

[0104] [Fifth Embodiment] In the first to fourth embodiments, the case in which the image processing device 100 and the printing device 111 are separate devices has been described, but the image processing device 100 may also be integrated into the printing device 111. In this case, the printing device 111 can notify the user whether it is necessary and possible to move the printing position of the image to be printed, based on the functions of the image processing device 100. The printing device 111 may also have a function (scanning function) to read images and characters formed on the recording medium.

[0105] Furthermore, the numerical values, processing timing, processing order, processing entity, data (information) destination / source / storage location, etc., used in each of the above embodiments are given as examples for the purpose of providing a concrete explanation, and are not intended to limit the scope to such examples.

[0106] Furthermore, some or all of the embodiments described above may be used in appropriate combinations. Alternatively, some or all of the embodiments described above may be used selectively.

[0107] (Other embodiments) The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0108] The disclosures herein include the following image processing apparatus, image processing methods, and computer programs.

[0109] (Item 1) An acquisition means for acquiring an image of density unevenness in a printed image caused by density unevenness in the nozzle row that ejects ink, A determination means for determining whether or not it is necessary to move the printing position of the printable image, based on the respective feature quantities of the printable image and the density unevenness image. An image processing apparatus characterized by comprising:

[0110] (Item 2) The image processing apparatus according to item 1, characterized in that the acquisition means generates a density unevenness image in which density unevenness corresponding to the density change amount is applied to the position corresponding to the defective nozzle in the nozzle row, based on the density change amount of the defective nozzle in the print image.

[0111] (Item 3) The image processing apparatus according to item 1 or 2, characterized in that the determination means determines that a shift in the printing position of the printable image is necessary if the difference between the visual features of the printable image and the visual features of the density unevenness image is greater than a threshold.

[0112] (Item 4) The image processing apparatus according to any one of items 1 to 3, characterized in that the determination means determines that movement of the printing position of the printable image is unnecessary if the difference between the visual feature quantities of the printable image and the visual feature quantities of the density unevenness image is less than or equal to a threshold.

[0113] (Item 5) moreover, An image processing apparatus according to any one of items 1 to 4, characterized in that it comprises a feasibility determination means for determining whether or not the printing position of the printable image can be moved, based on the difference between the visual feature quantities of a plurality of density uneven images, each of which density unevenness caused by a defective nozzle is added to the printable image placed at each position along the nozzle row, and the visual feature quantities of the printable image.

[0114] (Item 6) The image processing apparatus according to item 5, characterized in that the feasibility determination means determines that if the smallest difference among the differences is less than a threshold, it is possible to move the printing position of the printable image.

[0115] (Item 7) moreover, An image processing apparatus according to any one of items 1 to 4, characterized by comprising a feasibility determination means for determining whether or not the printing position of a printable image can be moved, based on the difference between the visual feature quantities of a plurality of density uneven images, each obtained by adding density unevenness due to a defective nozzle to a printable image rotated at a different rotation angle, and the visual feature quantities of the printable image.

[0116] (Item 8) The image processing apparatus according to item 7, characterized in that the feasibility determination means determines that if the smallest difference among the differences is less than a threshold, it is possible to move the printing position of the printable image.

[0117] (Item 9) The acquisition means acquires a first density unevenness image obtained by applying the density unevenness to a surface printing image to be printed on the surface of the recording medium, and a second density unevenness image obtained by applying the density unevenness to a back printing image to be printed on the back surface of the recording medium. The image processing apparatus according to item 1, characterized in that the determination means determines that movement of the printing positions of the front printing image and the back printing image is necessary if the difference between the visual features of the front printing image and the visual features of the first density unevenness image and / or the difference between the visual features of the back printing image and the visual features of the second density unevenness image is greater than a threshold.

[0118] (Item 10) The acquisition means acquires a first density unevenness image obtained by applying the density unevenness to a surface printing image to be printed on the surface of the recording medium, and a second density unevenness image obtained by applying the density unevenness to a back printing image to be printed on the back surface of the recording medium. The image processing apparatus according to item 1, characterized in that the determination means determines that movement of the printing position of the front printing image and the back printing image is unnecessary if the difference between the visual features of the front printing image and the visual features of the first density unevenness image and the difference between the visual features of the back printing image and the visual features of the second density unevenness image is less than a threshold.

[0119] (Item 11) moreover, The image processing apparatus according to item 9 or 10, characterized in that, for each of the printable image to be printed on the surface of the recording medium and the printable image to be printed on the back surface of the recording medium, the apparatus provides means for determining whether the printing position of the printable image to be printed on the surface of the recording medium and the printable image to be printed on the back surface of the recording medium can be moved, by obtaining the difference between the visual feature quantities of a plurality of density uneven images, each of which density unevenness caused by a defective nozzle is applied to the printable image placed at each position along the nozzle row, and the visual feature quantities of the printable image to be printed, and by determining whether the printing position of the printable image to be printed on the surface of the recording medium and the printable image to be printed on the back surface of the recording medium can be moved based on the difference.

[0120] (Item 12) moreover, The image processing apparatus according to item 9 or 10, characterized in that it comprises means for determining whether the printing position of the printable image to be printed on the surface of the recording medium and the printable image to be printed on the back surface of the recording medium can be moved, by obtaining the difference between the visual feature quantities of a plurality of density uneven images obtained by rotating each printable image to be printed on the surface of the recording medium at different rotation angles and adding density unevenness caused by a defective nozzle to each printable image, and determining whether the printing position of the printable image to be printed on the surface of the recording medium and the printable image to be printed on the back surface of the recording medium can be moved based on the difference.

[0121] (Item 13) moreover, An image processing apparatus according to any one of items 1 to 12, characterized by comprising a notification means for notifying the result of the determination by the determination means.

[0122] (Item 14) The image processing apparatus according to item 13, characterized in that, when it is determined that the printing position of the printable image can be moved, the notification means notifies that the recovery operation of the defective nozzle will be stopped until printing based on the print job in the printing apparatus is completed.

[0123] (Item 15) The image processing apparatus according to any one of items 1 to 14, characterized in that the aforementioned feature quantity is a frequency response characteristic of vision.

[0124] (Item 16) The image processing apparatus according to any one of items 1 to 14, characterized in that the aforementioned feature quantity is a color response characteristic of vision.

[0125] (Item 17) An image processing method performed by an image processing device, The acquisition means of the image processing apparatus includes an acquisition step of acquiring an image of density unevenness caused by the nozzles in the nozzle row that ejects ink, which is present in the printed image, The determination means of the image processing apparatus performs a determination step of determining whether or not it is necessary to move the printing position of the print image based on the respective feature quantities of the print image and the density unevenness image. An image processing method characterized by comprising:

[0126] (Item 18) A computer program for causing a computer to function as one of the means of an image processing apparatus described in any one of items 1 through 16.

[0127] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0128] 201: Input section 202: Input section 203: Judgment section 204: Calculation section 205: Judgment section 206: Notification section

Claims

1. An acquisition means for acquiring an image of density unevenness in a printed image caused by density unevenness in the nozzle row that ejects ink, A determination means for determining whether or not it is necessary to move the printing position of the print image based on the respective feature quantities of the print image and the density unevenness image, Notification means for notifying the result of the determination by the determination means and Equipped with, The image processing apparatus is characterized in that, when it is determined that the printing position of the printable image can be moved, the notification means notifies that the recovery operation of the defective nozzle will be stopped until printing based on the print job in the printing device is completed.

2. The image processing apparatus according to claim 1, characterized in that the acquisition means generates a density unevenness image in which density unevenness corresponding to the density change amount is applied to the position corresponding to the defective nozzle in the nozzle row, based on the density change amount of the defective nozzle in the print image.

3. The image processing apparatus according to claim 1, characterized in that the determination means determines that a movement of the printing position of the printable image is necessary if the difference between the visual feature quantities of the printable image and the visual feature quantities of the density unevenness image is greater than a threshold.

4. The image processing apparatus according to claim 1, characterized in that the determination means determines that movement of the printing position of the printable image is unnecessary if the difference between the visual feature quantities of the printable image and the visual feature quantities of the density unevenness image is less than or equal to a threshold.

5. moreover, The image processing apparatus according to claim 1, further comprising a feasibility determination means for determining whether or not the printing position of the printable image can be moved, based on the difference between the visual feature quantities of a plurality of density uneven images, each of which density unevenness caused by a defective nozzle is added to the printable image placed at each position along the nozzle row, and the visual feature quantities of the printable image.

6. The image processing apparatus according to claim 5, characterized in that the feasibility determination means determines that the printing position of the printable image can be moved if the difference of the density uneven image with the smallest difference among a plurality of differences calculated by comparing the visual feature quantities of each of the plurality of density uneven images with respect to the visual feature quantities of the printable image is less than a threshold.

7. moreover, The image processing apparatus according to claim 1, further comprising a feasibility determination means for determining whether or not the printing position of a printable image can be moved, based on the difference between the visual feature quantities of a plurality of density uneven images, each obtained by adding density unevenness due to a defective nozzle to a printable image rotated at a different rotation angle, and the visual feature quantities of the printable image.

8. The image processing apparatus according to claim 7, characterized in that the feasibility determination means determines that the printing position of the printable image can be moved if the difference of the density uneven image with the smallest difference among a plurality of differences calculated by comparing the visual feature quantities of each of the plurality of density uneven images with respect to the visual feature quantities of the printable image is less than a threshold.

9. The acquisition means acquires a first density unevenness image obtained by applying the density unevenness to a surface printing image to be printed on the surface of the recording medium, and a second density unevenness image obtained by applying the density unevenness to a back printing image to be printed on the back surface of the recording medium. The image processing apparatus according to claim 1, characterized in that the determination means determines that movement of the printing positions of the front printing image and the back printing image is necessary if the difference between the visual features of the front printing image and the visual features of the first density unevenness image and / or the difference between the visual features of the back printing image and the visual features of the second density unevenness image is greater than a threshold.

10. The acquisition means acquires a first density unevenness image obtained by applying the density unevenness to a surface printing image to be printed on the surface of the recording medium, and a second density unevenness image obtained by applying the density unevenness to a back printing image to be printed on the back surface of the recording medium. The image processing apparatus according to claim 1, characterized in that the determination means determines that movement of the printing position of the front printing image and the back printing image is unnecessary if the difference between the visual features of the front printing image and the visual features of the first density unevenness image and the difference between the visual features of the back printing image and the visual features of the second density unevenness image is less than a threshold.

11. moreover, The image processing apparatus according to claim 9, further comprising means for determining whether the printing positions of the printable image to be printed on the surface of the recording medium and the printable image to be printed on the back surface of the recording medium can be moved, wherein for each of these, the printable image to be printed on the surface of the recording medium and the printable image to be printed on the back surface of the recording medium are given density unevenness due to a defective nozzle, and the difference between the visual feature quantities of the printable image and the visual feature quantities of the printable image, and based on the difference, the means for determining whether the printing positions of the printable image to be printed on the surface of the recording medium and the printable image to be printed on the back surface of the recording medium can be moved.

12. moreover, The image processing apparatus according to claim 9, further comprising means for determining whether the printing position of the printable image to be printed on the surface of the recording medium and the printable image to be printed on the back surface of the recording medium can be moved, wherein for each of the printable image to be printed on the surface of the recording medium and the printable image to be printed on the back surface of the recording medium, the difference between the visual feature quantities of a plurality of density uneven images obtained by adding density unevenness due to a defective nozzle to each printable image rotated at different rotation angles and the visual feature quantities of the printable image to be printed, and based on the difference, the means for determining whether the printing position of the printable image to be printed on the surface of the recording medium and the printable image to be printed on the back surface of the recording medium can be moved.

13. An image processing method performed by an image processing device, The acquisition means of the image processing apparatus includes an acquisition step of acquiring an image of density unevenness caused by the nozzles in the nozzle row that ejects ink, which is present in the printed image, The determination means of the image processing apparatus includes a determination step of determining whether or not it is necessary to move the printing position of the print image based on the respective feature quantities of the print image and the density unevenness image, The notification means of the image processing device provides a notification process for notifying the result of the determination in the determination process. Equipped with, In the notification step, if it is determined that the printing position of the printable image can be moved, a notification is given that the recovery operation of the defective nozzle will be stopped until printing based on the print job in the printing device is completed. An image processing method characterized by the following:

14. A computer program for causing a computer to function as one of the means of an image processing apparatus according to any one of claims 1 to 12.

Images