Image forming apparatus

Abstract

To prevent a situation where printing is not performed in a specified color.SOLUTION: A printer 1 has a color balance adjustment unit 38 that performs hue adjustment for image data, and a notification unit 46 that performs notification on the basis of the amount of change in the hue and the amount of change in a pixel value of each pixel of the image data before and after the hue adjustment performed by the color balance adjustment unit 38. The notification unit 46 counts the number of pixels in which the amount of change in the hue before and after the color adjustment is equal to or more than a hue threshold, and in which the difference in the amount of change in the pixel value between a channel with the maximum change in the pixel value and a channel with the minimum change is equal to or less than a channel-to-channel pixel value difference threshold before and after the color adjustment, and performs notification when the ratio of the number of the pixels to the total number of pixels in the image data is higher than a pixel number threshold.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus, and is suitable for application to, for example, an image forming apparatus that performs color balance adjustment. [Background technology]

[0002] BACKGROUND ART Conventionally, there has been an image forming apparatus that performs color adjustment on image data using adjustment values ​​stored in a storage unit, and prints the color-adjusted image data on paper (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-225272 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in such an image forming apparatus, when image data that has undergone color adjustment using adjustment values ​​previously stored in a storage unit is printed, there are cases where the image data is not printed in the designated colors.

[0005] The present invention has been made in consideration of the above points, and aims to propose an image forming apparatus that can prevent printing in a designated color. [Means for solving the problem]

[0006] In order to solve this problem, the image forming apparatus of the present invention is provided with a color adjustment unit that performs color adjustment of image data, and a notification unit that provides notification based on changes in the color information of the image data before and after color adjustment by the color adjustment unit.

[0007] According to the present invention, if the user selects to stop printing in response to the notification, the printing of the image data can be stopped. [Effects of the Invention]

[0008] According to the present invention, if printing cancellation is selected in response to the notification, printing of image data can be canceled, thereby realizing an image forming device that can prevent printing from not being done in the specified color. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a block diagram showing the hardware configuration of a printer. [Figure 2] FIG. 2 is a block diagram showing the functional configuration of the printer. [Figure 3] 10 is a flowchart illustrating a printing process procedure. [Figure 4] 10 is a flowchart showing a procedure for counting the number of hue change pixels. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, modes for carrying out the invention (hereinafter referred to as embodiments) will be described with reference to the drawings. [1. Configuration of image forming device] As shown in FIG. 1, the hardware configuration of printer 1 includes a CPU 10, a ROM 12, a RAM 14, an operation panel 16, a network I / F 18, a paper feed tray 20, a printer engine 22, and a density sensor 24, which are interconnected via a printer bus 26.

[0011] A CPU (Central Processing Unit) 10 is an arithmetic device that controls the overall operation of the printer 1 by loading various programs stored in a ROM (Read Only Memory) 12 into a RAM (Random Access Memory) 14 and executing the programs. An operation panel 16 is composed of a panel that displays the status of the printer 1 and operation instructions, and buttons that allow the user to operate the printer 1.

[0012] The network I / F 18 is an interface such as a network or USB (Universal Serial Bus), and receives image data to be printed by the printer 1, which is sent from an external device, a PC (Personal Computer) 28. The CPU 10 generates print data in a format printable by the printer 1 from the image data received via the network I / F 18, and sends the print data to the printer engine 22 via the printer bus 26. The paper feed tray 20 transports paper onto a conveyor belt. The printer engine 22 has four image forming units, one for cyan, one for magenta, one for yellow, and one for black, and prints the print data on the surface of paper transported on the conveyor belt or on the conveyor belt itself.

[0013] The density sensor 24 measures the density values ​​of the monochromatic gradation patch images printed on the conveyor belt and the density values ​​on the ejected paper.

[0014] [2. Functional configuration of image forming device] As shown in FIG. 2, the functional configuration of the printer 1 includes a receiving unit 30, a color matching unit 32, an adjustment value input unit 34, an adjustment value storage unit 36, a color balance adjustment unit 38, a color conversion storage unit 40, a hue calculation unit 42, a search unit 44, a notification unit 46, a gradation correction unit 48, a binarization unit 50, and a printing unit 52.

[0015] The receiving unit 30 corresponds to the network I / F 18 (FIG. 1), acquires image data from an external device such as the PC 28, and outputs the image data to the color matching unit 32. The color matching unit 32 corresponds to the CPU 10 (FIG. 1), and performs color conversion processing to convert the image data input from the receiving unit 30 into printer CMYK values, which are values ​​in the printer color space, by known means, and outputs the converted image data, which is CMYK image data, to the color balance adjustment unit 38 and the hue calculation unit 42.

[0016] The adjustment value input unit 34 corresponds to the operation panel 16 and the CPU 10 (FIG. 1), and receives color balance adjustment values ​​input from the operation panel 16, and outputs them to the adjustment value storage unit 36. The adjustment value storage unit 36 ​​corresponds to the ROM 12 (FIG. 1), and stores the color balance adjustment values ​​input from the adjustment value input unit 34, and outputs them to the color balance adjustment unit 38. The color balance adjustment unit 38 corresponds to the CPU 10 (FIG. 1), and performs color balance adjustment using the CMYK image data input from the color matching unit 32 and the color balance adjustment values ​​input from the adjustment value storage unit 36, and outputs the CMYK image data after color balance adjustment to the hue calculation unit 42 and the gradation correction unit 48.

[0017] The color conversion storage unit 40, which serves as a storage unit, corresponds to the ROM 12 (FIG. 1) and stores a pre-created conversion table for converting printer CMYK values ​​into hues. The hue calculation unit 42 corresponds to the CPU 10 (FIG. 1) and calculates hues for all pixels of the CMYK image data before color balance adjustment input from the color matching unit 32 and the CMYK image data after color balance adjustment input from the color balance adjustment unit 38 by performing a 3D-LUT conversion process, a well-known hue conversion process, using the conversion table read from the color conversion storage unit 40. The hue calculation unit 42 then outputs the hues of the CMYK image data before color balance adjustment and the hues of the CMYK image data after color balance adjustment, as well as the CMYK image data before color balance adjustment and the CMYK image data after color balance adjustment, to the search unit 44.

[0018] The search unit 44 as a calculation unit corresponds to the CPU 10 (Figure 1), and compares the hue of the CMYK image data before color balance adjustment input from the hue calculation unit 42 with the hue of the CMYK image data after color balance adjustment for all pixels, and also compares the CMYK image data before color balance adjustment with the CMYK image data after color balance adjustment to count the number of hue-changed pixels, which is the number of pixels with a large hue difference and pixels for which there is a channel with a small difference in pixel value (CMYK value), and if the ratio of the number of hue-changed pixels to the total number of pixels in the image data is higher than a specified value which is a pixel number threshold, it determines that there is a high possibility that a hue change unintended by the user has occurred due to the color balance adjustment, and notifies the notification unit 46.

[0019] Specifically, the search unit 44 calculates the hue difference, which is the difference (amount of change) between the hue before and after color balance adjustment, for all pixels. Next, the search unit 44 extracts pixels whose hue difference is equal to or greater than a hue threshold value, for example, 2 degrees. Next, for each pixel whose hue difference is equal to or greater than the hue threshold value, the search unit 44 calculates the pixel value difference, which is the difference (amount of change) between the CMYK values ​​before and after color balance adjustment for the channel whose color balance has been adjusted. Here, the channel refers to each of CMYK. Next, the search unit 44 calculates the inter-channel pixel value difference, which is the difference between the pixel value difference of the channel with the largest pixel value difference and the pixel value difference of the channel with the smallest pixel value difference, and counts the number of hue-changed pixels, which is the number of pixels whose inter-channel pixel value difference differs by equal to or greater than the inter-channel pixel value difference threshold value, for example, 10 degrees.

[0020] In this way, when there are many pixels including channels in which the amount of change in pixel value is small despite the amount of change in hue being large, the search unit 44 determines that there is a high possibility that an unintended hue change has occurred.

[0021] When color balance adjustment results in a significant change in hue, pixel values ​​typically change significantly along with the hue change. For example, the pixel value of the M (magenta) channel changes from 150 to 200, and the pixel value of the Y (yellow) channel changes from 100 to 150. In contrast, if the Y (yellow) pixel value before color balance adjustment was 250, close to the upper limit of 255, the M (magenta) pixel value changes from 150 to 200, but the Y (yellow) pixel value only changes from 250 to 255. In this case, despite the significant change in hue, the change in the Y (yellow) pixel value is small. Furthermore, in this case, the pixel value difference of M (magenta) is at its maximum at 50 and the pixel value difference of Y (yellow) is at its minimum at 5, resulting in a pixel value difference between channels of 45, which is greater than the inter-channel pixel value difference threshold. When image data with many such pixels is printed, the resulting image may be printed with a hue unintended by the user. In response to this, the search unit 44 counts the number of hue-changed pixels, which is the number of such pixels, and if the ratio of the number of hue-changed pixels to the total number of pixels in the image data is higher than a specified value, it determines that there is a high possibility that an unintended hue change has occurred.

[0022] The notification unit 46 corresponds to the operation panel 16 and the CPU 10 (FIG. 1), and when the search unit 44 notifies the user that an unintended hue change is likely to have occurred, the notification unit 46 notifies the user by displaying a hue change occurrence warning, which is a warning indicating that a hue change unintended by the user may have occurred due to color balance adjustment, and a printability confirmation message, which is a message asking whether or not to print, on the operation panel 16. The notification unit 46 then receives a response from the user regarding whether or not to print via the operation panel 16, and if the response is yes, outputs a notification to the printing unit 52 to continue printing, whereas if the response is no, outputs a notification to the printing unit 52 to cancel printing.

[0023] The gradation correction unit 48 corresponds to the CPU 10 (FIG. 1), and performs a known gradation correction process on the CMYK image data after color balance adjustment that has been input from the color balance adjustment unit 38, and outputs the result to the binarization unit 50. The binarization unit 50 corresponds to the CPU 10 (FIG. 1), and performs a binarization process by a known ordered dither method on the CMYK image data after the gradation correction process that has been input from the gradation correction unit 48, and outputs the binary image to the printing unit 52.

[0024] When the printing unit 52 receives a notification from the notification unit 46 to continue printing, it prints the binary image received from the binarization unit 50 onto paper. On the other hand, when the printing unit 52 receives a notification from the notification unit 46 to cancel printing, it cancels printing.

[0025] [3. Printing process] Next, a print processing procedure RT1, which is a specific processing procedure for print processing by CPU 10, will be described using the flowchart shown in Fig. 3. When printer 1 is powered on, CPU 10 starts print processing procedure RT1 by reading and executing a print processing program from ROM 12, and proceeds to step SP1. In step SP1, CPU 10 receives image data transmitted from PC 28 by receiving unit 30 when the user operates PC 28 to select printer 1 and execute printing, and proceeds to step SP2.

[0026] In step SP2, the CPU 10 performs color conversion processing on the image data using the color matching unit 32 to convert it into printer CMYK values ​​and generate CMYK image data, and then proceeds to step SP3. In step SP3, the CPU 10 performs color balance adjustment on the CMYK image data using the color balance adjustment values ​​stored in the adjustment value storage unit 36 ​​using the color balance adjustment unit 38, and then proceeds to step SP4.

[0027] In step SP4, the CPU 10 uses the conversion table read from the color conversion memory unit 40 to calculate the hue for all pixels of the CMYK image data before and after color balance adjustment using the hue calculation unit 42, and then proceeds to step SP5.

[0028] In step SP5, the CPU 10 executes the hue change pixel counting process procedure SRT1 shown in FIG. 4 to perform the hue change pixel counting process and count the number of hue change pixels, and then proceeds to step SP6.

[0029] In step SP6, the CPU 10 determines whether the ratio of the number of hue-change pixels to the total number of pixels in the image data is higher than a specified value using the search unit 44. If a positive result is obtained here, this indicates that the ratio of the number of hue-change pixels to the total number of pixels is higher than the specified value, and therefore there is a high possibility that an unintended hue change has occurred in the image data, and in this case the CPU 10 proceeds to step SP7. In step SP7, the CPU 10 causes the notification unit 46 to display a hue change warning and a printability confirmation message on the operations panel 16, accepts input from the operations panel 16, and proceeds to step SP8.

[0030] In step SP8, the CPU 10 determines whether or not the input from the operation panel 16 indicated that printing is permitted. If a positive result is obtained here, this indicates that the user wishes to print despite being aware that an unintended change in hue may have occurred, and in this case the CPU 10 causes the notification unit 46 to output a notification to the printing unit 52 to continue printing, and proceeds to step SP10.

[0031] On the other hand, if a negative result is obtained in step SP8, this indicates that the user wishes to cancel printing if an unintended change in hue has occurred, and in this case the CPU 10 proceeds to step SP9. In step SP9, the CPU 10 outputs a print cancellation notification to the printing unit 52 via the notification unit 46. Next, the CPU 10 causes the printing unit 52 to cancel printing, proceeds to step SP13, and ends the printing processing procedure RT1.

[0032] On the other hand, if a negative result is obtained in step SP6, this means that printing will continue because the ratio of the number of hue-changed pixels to the total number of pixels is below a specified value and there is little possibility that an unintended hue change has occurred in the image data, and in this case the CPU 10 proceeds to step SP10. In step SP10, the CPU 10 performs gradation correction processing on the CMYK image data after color balance adjustment using the gradation correction unit 48, and proceeds to step SP11. In step SP11, the CPU 10 performs binarization processing on the CMYK image data after the gradation correction processing using the binarization unit 50 to create a binary image, and proceeds to step SP12. In step SP12, the CPU 10 prints on paper based on the binary image using the printing unit 52, proceeds to step SP13, and ends the printing processing procedure RT1.

[0033] [4. Hue change pixel counting procedure] Next, the specific processing procedure of the hue change pixel counting process by the CPU 10 will be described with reference to the flowchart shown in Fig. 4. The CPU 10 starts the hue change pixel counting process procedure SRT1 (Fig. 4) in step SP5 of the printing process procedure RT1 (Fig. 3), and then proceeds to step SP21. In step SP21, the CPU 10 uses the search unit 44 to calculate the hue difference between the hue of the CMYK image data before color balance adjustment and the hue of the CMYK image data after color balance adjustment for all pixels, and then proceeds to step SP22.

[0034] In step SP22, the CPU 10 causes the search section 44 to extract pixels whose hue difference is equal to or greater than the hue threshold value, and then proceeds to step SP23.

[0035] In step SP23, the CPU 10 calculates the pixel value difference between the CMYK values ​​before and after color balance adjustment for each pixel extracted in step SP3 using the search unit 44 for the channel on which color balance adjustment has been performed, and then proceeds to step SP24.

[0036] In step SP24, the CPU 10 uses the search unit 44 to calculate the inter-channel pixel value difference, which is the difference between the pixel value difference of the channel with the largest pixel value difference and the pixel value difference of the channel with the smallest pixel value difference, and counts the number of hue-changed pixels, which is the number of pixels whose inter-channel pixel value difference differs by more than the inter-channel pixel value difference threshold, then proceeds to step SP25, ends the hue-changed pixel counting processing procedure SRT1, and proceeds to step SP6 in the printing processing procedure RT1 (Figure 3).

[0037] [5. Effects, etc.] In the above configuration, the printer 1 performs color conversion processing on the image data received from the PC 28 to generate CMYK image data, and performs color balance adjustment on the CMYK image data using the color balance adjustment values ​​stored in the adjustment value storage unit 36.

[0038] The printer 1 then calculates the hue for all pixels in the CMYK image data before and after the color balance adjustment, counts the number of hue-changed pixels, which is the number of pixels in the CMYK image data that have a large hue difference before and after the color balance adjustment and that include channels with a small amount of change in pixel value, and if the ratio of the number of hue-changed pixels to the total number of pixels in the image data is higher than a specified value, notifies the user by displaying a hue change warning, which is a warning indicating that the color balance adjustment may have caused a hue change unintended by the user, and a printability confirmation message, which is a message asking whether or not to print, on the operation panel 16. The printer 1 then continues printing if the user selects to continue printing, and cancels printing if the user selects to cancel printing.

[0039] For this reason, even if the color balance adjustment values ​​are input to the printer 1 at a stage prior to the current printing and stored in the adjustment value storage unit 36 ​​and the color balance adjustment values ​​are used to perform color balance adjustment on the CMYK image data in the current printing, by allowing the user to choose whether or not to print when there is a high possibility that the hue will be significantly distorted before and after the color balance adjustment, it is possible to prevent printing from being performed in a state where there is a possibility that the hue will be distorted.

[0040] Furthermore, the printer 1 can avoid unnecessary printing in colors that the user does not intend, thereby eliminating the need to waste paper and toner, and the need for the user to contact the manufacturer.

[0041] According to the above configuration, the printer 1 is provided with a color balance adjustment unit 38 that performs hue adjustment as a color adjustment of the image data, and a notification unit 46 that issues a notification based on the change in color information of the image data before and after the hue adjustment by the color balance adjustment unit 38 (i.e., the change in hue and the change in pixel value of each pixel).

[0042] This allows the printer 1 to stop printing the image data if the user selects to stop printing in response to the notification.

[0043] 6. Other Embodiments In the above-described embodiment, the printer 1 displays a hue change warning and a printability confirmation message on the operation panel 16. However, the present invention is not limited to this, and the printer 1 may transmit a hue change warning and a printability confirmation message to the PC 28 and display the hue change warning and the printability confirmation message on a monitor of the PC 28.

[0044] In the above-described embodiment, the printer 1 calculates the inter-channel pixel value difference, which is the difference between the pixel value difference of the channel with the largest pixel value difference and the pixel value difference of the channel with the smallest pixel value difference, in step SP24 of the hue-change pixel counting processing procedure SRT1 (FIG. 4), and counts the number of hue-change pixels, which is the number of pixels whose inter-channel pixel value difference differs by more than the inter-channel pixel value difference threshold. However, the present invention is not limited to this, and the printer 1 may also count the number of hue-change pixels, which is the number of pixels including channels whose pixel value difference is less than a predetermined pixel value difference threshold.

[0045] Furthermore, in the above-described embodiment, the present invention has been described as being applied to a printer 1 that performs color balance adjustment on image data including four channels of CMYK. However, the present invention is not limited to this, and may be applied to a printer 1 that performs color balance adjustment on image data including at least two channels (i.e., multiple channels).

[0046] Furthermore, in the above-described embodiment, the present invention has been described as being applied to the printer 1. However, the present invention is not limited to this, and may be applied to various devices that perform processing by adjusting the color balance of image data, such as a facsimile, an MFP (Multifunction Printer), or a copier.

[0047] Furthermore, the present invention is not limited to the above-described embodiment and other embodiments. That is, the scope of application of the present invention extends to embodiments in which the above-described embodiment and the other embodiments are combined in part or in whole. The scope of application of the present invention also extends to embodiments in which part of the configuration described in any of the above-described embodiment and other embodiments is extracted and used as part of the configuration of any of the above-described embodiment and other embodiments, or in which part of the extracted configuration is added to any of the above-described embodiment.

[0048] Furthermore, in the above-described embodiment, the printer 1 as an image forming apparatus is configured by the color balance adjustment unit 38 as a color adjustment unit and the notification unit 46 as a notification unit. However, the present invention is not limited to this, and the image forming apparatus may be configured by a color adjustment unit and a notification unit having various other configurations. [Industrial Applicability]

[0049] The present invention can be used in an image forming apparatus that performs color balance adjustment. [Explanation of symbols]

[0050] 1...Printer, 10...CPU, 12...ROM, 14...RAM, 16...Operation panel, 18...Network I / F, 20...Paper feed tray, 22...Printer engine, 24...Density sensor, 26...Printer bus, 28...PC, 30...Receiving unit, 32...Color matching unit, 34...Adjustment value input unit, 36...Adjustment value memory unit, 38...Color balance adjustment unit, 40...Color conversion memory unit, 42...Hue calculation unit, 44...Searching unit, 46...Notification unit, 48...Gradation correction unit, 50...Binarization unit, 52...Printing unit.

Claims

1. a color adjustment unit that performs color adjustment on the image data; a notification unit that notifies based on a change in color information of the image data before and after the color adjustment by the color adjustment unit; An image forming apparatus comprising:

2. a calculation unit that calculates the amount of change in the hue and pixel value, which are the color information, due to the color adjustment; and The notification unit The notification is made based on the amount of change in hue and the amount of change in pixel value in the image data before and after the color adjustment by the color adjustment unit.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. The calculation unit counting the number of pixels for which the amount of change in hue before and after the color adjustment is equal to or greater than a hue threshold and for which the difference between the amount of change in pixel value of the channel with the largest amount of change and the amount of change in pixel value of the channel with the smallest amount of change before and after the color adjustment is equal to or less than an inter-channel pixel value difference threshold, and determining whether the ratio of the number of pixels to the total number of pixels in the image data is higher than a pixel number threshold; The notification unit performs the notification when the calculation unit determines that the ratio is higher than the pixel number threshold.

3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

4. The calculation unit counting the number of pixels including channels in which the amount of change in hue before and after the color adjustment is equal to or greater than a hue threshold and the amount of change in pixel value before and after the color adjustment is equal to or less than a pixel value difference threshold, and determining whether the ratio of the number of pixels to the total number of pixels in the image data is higher than a pixel number threshold; The notification unit performs the notification when the calculation unit determines that the ratio is higher than the pixel number threshold.

3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

5. a storage unit for storing the adjustment values ​​of the color adjustment; and The color adjustment unit The color adjustment of the image data is performed based on the adjustment value stored in the storage unit.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

6. The notification unit The notification allows the user to select whether to continue printing or stop printing.

6. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: a first fixing member;

7. a printing unit that, in response to the notification by the notification unit, executes printing of the image data if continuation of printing is selected, and stops printing of the image data if stop of printing is selected; 7. The image forming apparatus according to claim 6, further comprising:

Images