Image processing device, image forming device, and image processing method

Abstract

To prevent show-through on a latent image without increasing the size of an image forming apparatus.SOLUTION: The present invention is an image processing apparatus comprising a print information acquisition unit, a latent image information acquisition unit, and a latent show-through prevention processing unit. The print information acquisition unit acquires print information from data for printing. The latent image information acquisition unit acquires latent image information from the data for printing. The latent image show-through prevention processing unit performs show-through prevention processing when the print information is set to double-sided printing and objects of the data for printing include a latent image.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to an image processing apparatus, an image forming apparatus, and an image processing method. [Background technology]

[0002] Conventionally, in a double-sided printed document, when another image is printed on the reverse side of a latent image, the latent image may become unrecognizable due to show-through of the other image.

[0003] Patent Document 1 discloses a method for suppressing show-through in which a white color material is formed and printed on a base of a printed portion of a colored color material. Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional technique for suppressing show-through, which involves creating and printing a white color material on a background of a colored image, an image-forming unit for forming the white color material is required in the image forming device, which poses the problem of increasing the size of the image forming device.

[0005] The present invention has been made in consideration of the above, and aims to provide an image processing device, an image forming device, and an image processing method that are capable of suppressing show-through of a latent image without increasing the size of the image forming device. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present invention provides an image processing device including a print information acquisition unit, a latent image information acquisition unit, and a latent image show-through suppression processing unit, the print information acquisition unit acquiring print information from print data, the latent image information acquisition unit acquiring latent image information from the print data, and the latent image show-through suppression processing unit performing show-through suppression processing when the print information is set for double-sided printing and a latent image is included in an object of the print data. the color material of the latent image is a color material that is read in a latent image reading wavelength range of the latent image that is different from a reading wavelength range of the visible image after printing, and the show-through suppression processing is processing for correcting settings of the color material of an image to be printed on the reverse side of the printing surface on which the latent image is printed. It is characterized by: Effect of the Invention

[0007] According to the present invention, it is possible to suppress show-through of a latent image without increasing the size of an image forming apparatus. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing the overall configuration of a printing system according to a first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating a schematic configuration of the image forming apparatus. [Diagram 3] FIG. 3 is a block diagram showing a hardware configuration of the image forming apparatus. [Figure 4] FIG. 4 is a block diagram showing the hardware configuration of a client PC. [Diagram 5] FIG. 5 is a functional block diagram showing functions in the printing system. [Figure 6] FIG. 6 is a diagram showing an example of a latent image synthesis technique. [Figure 7] FIG. 7 is a diagram showing an example of holding selected latent image area information. [Figure 8] FIG. 8 is a diagram illustrating an example of the configuration of the back-reflection prevention unit in the image processing device. [Figure 9] FIG. 9 is a diagram showing an example of a flow of a latent image show-through suppression process performed by an image processing apparatus. [Figure 10] FIG. 10 is a diagram showing the effect of performing the latent image show-through suppression process. [Figure 11] FIG. 11 is a diagram illustrating an example of the configuration of the back-reflection prevention unit according to the first modification. [Figure 12] FIG. 12 is a diagram showing an example of a flow of a latent image show-through suppression process performed by an image processing apparatus. [Figure 13] FIG. 13 is an explanatory diagram of a process for suppressing show-through according to the second modification. [Figure 14] FIG. 14 is a diagram showing an example of a flow of a latent image show-through suppression process performed by an image processing device according to the second modification. [Figure 15]FIG. 15 is a diagram showing an example of a flow of a latent image show-through suppression process performed by an image processing device according to the third modification. [Figure 16] FIG. 16 is a diagram showing an example of conversion of pixel values ​​of the K plate performed by the image processing apparatus. [Figure 17] FIG. 17 is a diagram illustrating an example of the configuration of the back-reflection prevention unit according to the fourth modification. [Figure 18] FIG. 18 is a diagram showing an example of a flow of a latent image show-through suppression process performed by an image processing device according to the fourth modification. [Figure 19] FIG. 19 is a diagram showing an example of conversion of pixel values ​​of the K plate performed by the image processing device. [Figure 20] FIG. 20 is a diagram illustrating an example of the configuration of the back-reflection prevention unit according to the fifth modification. [Figure 21] FIG. 21 is a diagram showing an example of a flow of a latent image show-through suppression process performed by an image processing apparatus. [Figure 22] FIG. 22 is a diagram illustrating an example of the configuration of the back-reflection prevention unit according to the sixth modification. [Diagram 23] FIG. 23 is a diagram showing an example of a flow of a latent image show-through suppression process performed by an image processing apparatus. [Figure 24] FIG. 24 is a diagram showing an example of the effect of the latent image show-through suppression processing of the sixth modification. [Diagram 25] FIG. 25 is a diagram illustrating an example of the configuration of the back-reflection prevention unit according to the seventh modification. [Figure 26] FIG. 26 is a diagram showing an example of a flow of a latent image show-through suppression process performed by an image processing apparatus. [Figure 27] FIG. 27 is a diagram illustrating an example of the configuration of the back-reflection prevention unit according to the eighth modification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an image processing apparatus, an image forming apparatus, and an image processing method will be described in detail with reference to the accompanying drawings.

[0010] (First embodiment) Fig. 1 is a block diagram showing the overall configuration of a printing system according to a first embodiment. As shown in Fig. 1, the printing system includes one or more client PCs (Personal Computers) 300, a print server 400, and an image forming device 100, which are connected via a network 500. The client PCs 300 and the image forming device 100 are each electronic devices.

[0011] An overview of the print processing in the print system will be described. Document data created within an application on the client PC 300 is converted into print data via a printer driver inside the client PC 300. The print data is sent from the client PC 300 to the image forming apparatus 100, where it is edited and analyzed by an image processing device inside the image forming apparatus 100 and converted into printable raster data. The raster data is printed by the plotter of the image forming apparatus 100.

[0012] In addition, print data may be sent from client PC 300 to print server 400, and after the print server 400 edits the print data and performs necessary settings, the print server 400 may transmit the print data to image forming apparatus 100.

[0013] Also, instead of sending print data from client PC 300, a document that has been saved in print server 400 in advance may be sent directly to image forming apparatus 100.

[0014] 2 is a diagram showing a schematic configuration of the image forming apparatus 100. The image forming apparatus 100 is a multifunction machine having at least two of a copy function, a printer function, a scanner function, and a facsimile function.

[0015] As shown in FIG. 2, the image forming apparatus 100 includes a paper feed section 103, an apparatus main body 104, a scanner 101, and an automatic document feeder (ADF) .

[0016] The image forming apparatus 100 includes a plotter 120, which is an image forming unit, in an apparatus body 104. The plotter 120 includes a tandem imaging unit 105, a registration roller 108 that supplies recording paper from a paper feed unit 103 to the imaging unit 105 via a transport path 107, an optical writing device 109, a fixing unit 110, and a double-sided tray 111.

[0017] In the image forming unit 105, four photoconductor drums 112 are arranged in parallel to correspond to four colors, namely, Y (yellow), M (magenta), C (cyan), and K (infrared absorbing visible toner (black)). Around each photoconductor drum 112, image forming elements including a charger, a developing unit 106, a transfer unit, a cleaner, and a static eliminator are arranged. In addition, between the transfer unit and the photoconductor drum 112, an intermediate transfer belt 113 is arranged, which is sandwiched in the nip between the two and stretched between a drive roller and a driven roller.

[0018] That is, the image forming apparatus 100 creates an infrared latent image using general-purpose CMYK toners, without using a special transparent toner. Since the CMY toners are transparent, the infrared sensing device can only display the portion where the black toner is embedded.

[0019] In the tandem type image forming apparatus 100 configured in this manner, based on an original image read by the scanner 101 from an original sent from the ADF 102, an optical writing device 109 optically writes onto photoconductor drums 112 corresponding to each color of Y, M, C, and K, and the toner of each color is developed by the developing device 106, and primarily transferred onto the intermediate transfer belt 113 in the order of Y, M, C, and K, for example. Then, the image forming apparatus 100 secondarily transfers the full-color image in which the four colors are superimposed by the primary transfer onto recording paper supplied from the paper feed unit 103, and then fixes the image in the fixing unit 110 and discharges the paper, thereby forming a full-color image on the recording paper.

[0020] Next, the hardware configuration of the image forming apparatus 100 will be described.

[0021] 3 is a block diagram showing a hardware configuration of the image forming apparatus 100. As shown in FIG 3, the image forming apparatus 100 is provided with an image processing apparatus 200 that performs predetermined processing on an original image read by a scanner 101 and outputs the processed image to a plotter 120 as image data.

[0022] The image processing device 200 includes a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, a main memory 205, a chipset 206, an image processing ASIC 207, a controller ASIC 208, a main memory 209, and an I / O ASIC 210. Note that ASIC is an abbreviation for Application Specific Integrated Circuit.

[0023] The CPU 201 is for controlling the image forming apparatus 100. The main memory 205 is a frame memory (image memory) in which programs (applications, OS, printer driver, and other programs) for the CPU 201 to control the image forming apparatus 100 are expanded and used as a work area for the programs, and for temporarily storing image data to be handled. The chipset 206 is used together with the CPU 201 and controls the access of the controller ASIC 208 and the I / O ASIC 210 to the main memory 205.

[0024] The program executed by image forming apparatus 100 of this embodiment may be configured to be provided by recording it on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, or a digital versatile disk (DVD) in an installable or executable format file.

[0025] Furthermore, the program executed by image forming apparatus 100 of the present embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Also, the program executed by image forming apparatus 100 of the present embodiment may be provided or distributed via a network such as the Internet.

[0026] The scanner 101 has a function of reading image data to be copied or output to an external interface. The plotter 120 has a function of printing image data stored in the main memory 209.

[0027] The image processing ASIC 207 performs image processing on image data read by the scanner 101 and outputs the image data to the controller ASIC 208. The image processing ASIC 207 also processes image data from the controller ASIC 208 so that the image data can be printed by the plotter 120, and sends the image data in accordance with the printing timing of the plotter 120.

[0028] The controller ASIC 208 rotates and edits image data handled by the image forming apparatus 100 using the main memory 205 via the chipset 206, stores the image data in the HDD 211, and transmits and receives the image data to and from the image processing ASIC 207. The main memory 209 is used as an image memory for the controller ASIC 208 to perform image processing. The HDD (Hard Disk Drive) 211 is a storage used to temporarily store image data that has been subjected to image processing.

[0029] The I / O ASIC 210 is an external interface for providing additional functions to the image forming apparatus 100. For example, the I / O ASIC 210 is equipped with interfaces such as a network interface, a USB, an SD card, an operation unit, SPI, I2C, and a document width sensor 85 (width detection sensors SN1 to SN5), a hardware accelerator for accelerating image processing, an encryption processing circuit, and the like.

[0030] Next, the hardware configuration of the client PC 300 will be described.

[0031] 4 is a block diagram showing a hardware configuration of the client PC 300. In the following description, the hardware configuration of the client PC 300 will be described using the hardware configuration of a general PC or the like as an example.

[0032] 4, in the client PC 300, a CPU (Central Processing Unit) 10, a RAM (Random Access Memory) 20, a ROM (Read Only Memory) 30, a HDD (Hard Disk Drive) 40, and an I / F 50 are connected via a bus 80. In addition, an LCD (Liquid Crystal Display) 60 and an operation unit 70 are connected to the I / F 50.

[0033] The CPU 10 is a computing means and controls the overall operation of the client PC 300. The RAM 20 is a volatile storage medium capable of reading and writing information at high speed, and is used as a working area when the CPU 10 processes information. The ROM 30 is a read-only non-volatile storage medium in which programs such as firmware are stored. The HDD 40 is a non-volatile storage medium in which information can be read and written, and in which the OS (Operating System), various control programs, application programs, printer drivers, etc. are stored.

[0034] The I / F 50 connects the bus 80 to various hardware devices, the network 500, etc., and controls them. In other words, the I / F 50 is an interface that enables the client PC 300 to communicate with other devices, such as the image forming apparatus 100, via the network 500. The LCD 60 is a visual user interface that enables the user to check various pieces of information. The operation unit 70 is a user interface, such as a keyboard or a mouse, that enables the user to input information to the client PC 300.

[0035] In such a hardware configuration, a software control unit is configured by reading a program stored in a storage medium such as ROM 30, HDD 40, or an optical disk (not shown) into RAM 20, and the CPU 10 performs calculations according to the program loaded into RAM 20. A functional block that realizes the functions of the client PC 300 according to this embodiment is configured by combining the software control unit configured in this way with hardware.

[0036] The program executed by client PC 300 of this embodiment is provided as a file in an installable or executable format recorded on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, or a DVD (Digital Versatile Disk).

[0037] The program executed by the client PC 300 of this embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. The program executed by the client PC 300 of this embodiment may be provided or distributed via a network such as the Internet.

[0038] Next, functions performed by the printing system will be described. Here, the image processing device 200 and the client PC 300 in the overall configuration diagram of the printing system in Fig. 1 will be used for the description, but any information processing device such as a print server 400 may be used instead of the client PC 300. Furthermore, the functions performed by the image processing device 200 may also be arranged in an information processing device such as the client PC 300 or the print server 400.

[0039] 5 is a functional block diagram showing functions in the printing system. Note that, here, among the functions performed by the image processing device 200 and the client PC 300, characteristic functions in this embodiment will be described.

[0040] The image processing device 200 generally has a function of embedding a latent image in a background image in double-sided printing, and a function of performing image processing on the image on the back side of the latent image.

[0041] Here, the background image refers to a visible image in which a latent image is embedded. A visible image in which a latent image is embedded is called a latent-image-embedded image. A latent image is image information that is difficult to see due to a visible image, but can only be detected in a specific observation environment. A latent image refers to a background image in which a latent image is embedded as an image. For example, a latent image is code information that can only be detected by a sensing device that responds to infrared light. A back image refers to an image printed on the back side of a printing surface on which a latent image is printed in a double-sided printing setting. For example, if a latent image is printed on the front side of a printing surface in double-sided printing, the image on the back side of the printing surface becomes the back image, and if a latent image is printed on the back side of a printing surface in double-sided printing, the image on the front side of the printing surface becomes the back image.

[0042] FIG. 6 is a diagram showing an example of a latent image synthesis method. FIG. 6 shows an image expressed by a QR code (registered trademark) as an example of a latent image. As shown in FIG. 6, an arbitrary background image composed of RGB is converted from RGB to CMY. The latent image is converted to monochrome by converting the RGB components to luminance values. Here, for the background image converted to CMY, the amount of black generated is changed according to the latent image density at the same pixel position, rather than performing black generation using a black generation table with a fixed number of pixels. For example, if the latent image at the same position as the background pixel is a white pixel, black generation is not performed, and only the CMY value is left. If the latent image at the same position as the background pixel is a black pixel, a process to make it high black is performed to create a CMYK image in which black generation has been performed. Note that the black processing table is adjusted so that the same color reproduction is performed in the case of low black and the case of high black. In FIG. 6, a method of embedding a background image composed of RGB has been described, but if the background image is a CMYK image, it is sufficient to convert the CMYK signal to a CMY signal or RGB signal once and convert it into a latent image embedded image using the method of FIG. 6.

[0043] When such a CMYK image is printed by the image forming apparatus 100, there is no difference in color between the low and high ink areas, so only the original background image is recognized when observed with the naked eye under visible light. However, because the amount of ink generation is dynamically changed based on the density of the latent image, when detected with a sensing device that responds to infrared light, a K plate latent image is detected as shown in Figure 6.

[0044] Here, under infrared light, the cyan, magenta, and yellow colorants that do not contain carbon exhibit high transmittance, while the black colorant that uses carbon black exhibits high absorption. When the latent image is confirmed with an infrared sensing device, the CMY toners become transparent and only the part printed with the K toner is detected as black, so the latent image can be confirmed with the infrared sensing device. In this way, it is possible to embed a latent image by adjusting the combination of colorants with different optical properties for any background image. Here, the image of the K toner holds the latent image, and the image of the CMY toners acts as a mask to hide the latent image.

[0045] In this embodiment, a method of adjusting the amount of ink generation will be described, but as a method of embedding a latent image by combining color materials with different optical properties, there is also a method of combining a black mask with a background image and adjusting the amount of K in the black mask to embed the latent image, and either method may be used. In either method, the latent image is held by adjusting the combination of color materials with different optical properties, so the generated latent-image-embedded image is held in an image format that can hold the amount of color material to be printed.

[0046] For example, when printing with the image forming apparatus 100 that prints in cyan, magenta, yellow, and black, the image format is stored in CMYK. When using color materials other than the above (for example, light cyan and light magenta), it is necessary to store the image in an image format that can record the amount of all color materials.

[0047] In this embodiment, a method of embedding an infrared latent image is exemplified by using carbon black, which exhibits high infrared absorption, and cyan, magenta, and yellow color materials, which exhibit high infrared transmittance. However, an ultraviolet latent image may be embedded by utilizing a combination of color materials, which exhibit high absorption or transmittance for ultraviolet components.

[0048] When a printer driver for latent image printing is specified from an application and a print instruction is given, a print preview screen is launched. On the print preview screen, the user can select the information that he / she wants to conceal as a latent image. Once the latent image selection is complete and a print instruction is given, the object selected as the latent image is extracted from the print data, and the latent image is combined with any background information, converted into a latent image embedded image, and printed. In this way, the user can conceal any information in an existing application as a latent image.

[0049] QR codes concealed as latent images cannot be detected by the naked eye or by ordinary RGB scanners, and can only be detected and decoded by infrared sensing devices. This makes it possible to create QR codes that are extremely difficult to tamper with or counterfeit. In addition, because the latent image is destroyed and cannot be copied when copying with an ordinary copy machine, it is also possible to determine whether the code has been copied or counterfeited.

[0050] 5, the client PC 300 includes a latent image area setting unit 310. The image processing device 200 also includes an image processing unit 260 and a RIP (Raster Image Processing) unit 270.

[0051] 5, when a print instruction is given, the application of the client PC 300 generates print data via a drawing API and a printer driver graphics function of the operation system of the client PC 300. This print data is generally in a command data format called PDL (Page Description Language) that can be interpreted by the image forming apparatus 100.

[0052] The latent image area setting unit 310 interprets the print data generated by the printer driver of the client PC 300 and draws a print image as a print preview screen on the screen of the client PC 300. On the print preview screen, the user can select an area that he or she wishes to conceal as a latent image.

[0053] Here, Fig. 7 is a diagram showing an example of holding selected latent image area information. As shown in Fig. 7, the area selected on the preview screen is held as latent image area information (area designation information by coordinates) in the print image. Note that latent image area information can be set in multiple locations per page.

[0054] The latent image area information designated in the latent image area setting unit 310 is transmitted to the image processing device 200 together with the print data, and passed to the image processing unit 260 .

[0055] The image processing unit 260 receives the printing data, and when the latent image area information is included, embeds the latent-image-embedded image in the background image as described above to generate printing data with the latent-image-embedded image. Furthermore, when the printing data is set for double-sided printing, the image processing unit 260 applies a process to suppress show-through to the back side image. The process to suppress show-through in the image processing unit 260 will be described in detail below.

[0056] Fig. 8 is a diagram showing an example of the configuration of the show-through suppression unit in the image processing device 200. As shown in Fig. 8, the image processing unit 260 includes a print information acquisition unit 261, a latent image information acquisition unit 262, and a latent image show-through suppression processing unit 263 as means for suppressing show-through.

[0057] The print information acquisition unit 261 acquires print information from the print data. The latent image information acquisition unit 262 acquires latent image information from the print data. The latent image show-through prevention processing unit 263 applies latent image show-through prevention processing to the back side image of the print data based on the print information and the latent image information.

[0058] Here, the printing data is command data that can be interpreted by a printer, for example, called PDL (Printer Description Language). Printing data written in PDL is generally composed of the number of pages, the type of object for each page (image, line, figure, or character), coordinate data indicating the printing position, an instruction for single-sided or double-sided printing, and setting data such as the printing direction or paper size. Printing information refers to coordinate data and setting data, and latent image information refers to page information containing a latent image and coordinate data of the latent image.

[0059] When the printing information indicates double-sided printing and the printing data includes latent image information, the latent image show-through suppression processing unit 263 performs latent image show-through suppression processing on the back side image of the latent image information and outputs the printing data to the RIP processing unit 270. In other words, the image processing unit 260 outputs printing data with a latent-image-embedded image, including the back side, to the RIP processing unit 270.

[0060] The latent image show-through suppression process for the back side image is, for example, a process for lowering the image density of the back side image. Note that, as long as the latent image show-through suppression process can suppress show-through so that the latent image can be read, other methods may be used as appropriate.

[0061] After the print data is subjected to a latent image show-through suppression process, it is converted into raster data by the RIP processing unit 270. Raster data is data in a matrix format made up of pixel coordinates and pixel values.

[0062] 9 is a diagram showing an example of a flow of a latent image show-through suppression process performed by the image processing device 200. The image processing device 200 first determines whether double-sided printing is performed based on the printing information of the received printing data (S1), and if it determines that double-sided printing is not performed (S1: No), ends the latent image show-through suppression process.

[0063] Furthermore, when the image processing device 200 determines that double-sided printing is to be performed (S1: Yes), it then determines whether or not a latent image is included in the object of the print data (S2). When the image processing device 200 determines that a latent image is not included in the object of the print data (S2: No), it ends the latent image show-through suppression process.

[0064] Furthermore, when the image processing device 200 determines that a latent image is included in the object of the print data (S2: Yes), it executes suppression of latent image show-through (S3) and ends the latent image show-through suppression process.

[0065] Here, double-sided printing refers to printing on both sides of the recording paper, such as booklet printing. Whether or not an object in the print data contains a latent image is determined by, for example, whether the object is an object in which an image made in CMY is overlaid on a 2D code made in K.

[0066] Fig. 10 is a diagram showing the effect of performing latent image show-through suppression processing. Fig. 10 shows the results of reading the latent image when the image processing device 200 performs show-through suppression processing and when it does not perform show-through suppression processing, taking as an example a case where an image of the K version of the character "aiu" is printed on the back side of a page with a latent image. Note that the latent image is assumed to be a QR code and is read from the page side with the latent image.

[0067] As shown in Figure 10, without the latent image bleed-through prevention process, the K plate characters on the back side are read as bleed-through and overlap the latent image of the QR code. In this case, the QR code is not detected correctly and cannot be decoded.

[0068] On the other hand, if latent image show-through prevention processing is applied, show-through of the K version characters on the back side is suppressed, so the latent image of the QR code can be read, making it possible to detect and decode the QR code.

[0069] In this way, in the present embodiment, when a latent image is included, the back side image can be prevented from showing through, so that the latent image can be read accurately. In addition, since a general toner configuration such as CMYK is sufficient, the device can be implemented without increasing its size.

[0070] (Variation 1) A description will be given of Modification 1 of the image processing device 200. Here, the description of the points common to the embodiment will be omitted as appropriate, and only the points that are different will be described.

[0071] Fig. 11 is a diagram showing an example of the configuration of a show-through suppression unit according to Modification 1. As shown in Fig. 11, the image processing unit 260 has a latent image show-through suppression processing unit 263 having a latent image back image correction unit 263-1 as a means for suppressing show-through.

[0072] The latent image back side image correcting unit 263-1 corrects the image of the processing page when the processing page is a page on the back side of a page including a latent image (referred to as a latent image back side page).

[0073] FIG. 12 is a diagram showing an example of a flow of a latent image show-through suppression process performed by the image processing device 200. The flow shown in FIG. 12 is obtained by adding S21 to the flow shown in FIG. 9. As shown in FIG. 12, after S1 (Yes) and S2 (Yes), the image processing device 200 determines in step S21 whether the processing page is a latent image back page. When the image processing device 200 determines that the processing page is not a latent image back page (S21: No), it ends the latent image show-through suppression process. When the image processing device 200 determines that the processing page is a latent image back page (S21: Yes), it executes latent image back image correction, that is, suppression of latent image show-through (S3), and ends the latent image show-through suppression process.

[0074] In this way, the image processing device according to the first modification can perform the latent image show-through suppression process on the back side of a page including a latent image in a processing page unit.

[0075] (Variation 2) A second modified example of the image processing device 200 will be described. The cause of show-through onto the latent image is the K-image formed on the back side of the latent image. Therefore, as the second modified example, a modified example in which the black image of the K-image is replaced with a black image composed of CMY will be shown.

[0076] FIG. 13 is an explanatory diagram of a process for suppressing show-through according to the second modified example. As shown in FIG. 13, the K colorant of the black toner exhibits high light absorption in the infrared range, which causes show-through, but the K colorant composed of CMY exhibits low light absorption in the infrared range, which suppresses show-through. In other words, the printed portion of the K colorant composed of CMY has almost the same reflectance as the printed portion of the K colorant in the visible light range (420 to 680 nm) and can be read in the same way as the K colorant, but transmits light in the infrared range (780 to 1100 nm) and becomes invisible. Therefore, show-through in the latent image can be suppressed by replacing the K plate of the latent image backside image with the CMY plate and using the K colorant composed of CMY instead of the K colorant.

[0077] Fig. 14 is a diagram showing an example of a flow of a latent image show-through suppression process performed by the image processing device 200 according to Modification 2. The flow shown in Fig. 14 is obtained by replacing the process of S3 in the flow shown in Fig. 12 with S31. The image processing device 200 executes a process of replacing the K plate with the CMY plate (S31), and ends this latent image show-through suppression process.

[0078] (Variation 3) A third modification of the image processing device 200 will be described. The cause of show-through in the latent image is the image of the K plate formed on the back side of the latent image. Therefore, as the third modification, a modification in which the pixel value of the K plate is lowered will be shown.

[0079] Fig. 15 is a diagram showing an example of a latent image show-through suppression processing flow performed by the image processing device 200 according to Modification 3. The flow shown in Fig. 15 is obtained by replacing the processing of S3 in the flow shown in Fig. 12 with S32. The image processing device 200 executes processing to reduce the pixel value of the K plate (S32), and ends this latent image show-through suppression processing.

[0080] FIG. 16 is a diagram showing an example of conversion of pixel values ​​of the K plate performed by the image processing device 200. In the input / output relationship shown in FIG. 16(a), the input pixel value is converted to a low output pixel value and output. Specifically, as shown in FIG. 16(a), the pixel values ​​of the image are uniformly converted to 128 / 255 times (rounded up, maximum density 255) to lower the pixel value. Since the input pixel value 255 is converted to the output pixel value 128 in the relationship of FIG. 16(a), the pixel value of the entire K plate is lowered from 255 before correction to 128 after correction as shown in FIG. 16(b), and printing is performed at a low density. As a result, the density of the back image of the latent image becomes low and difficult to read, so that show-through is suppressed.

[0081] 16A is an example, and is not limited to this. If the pixel value is equal to or less than a certain value, show-through can be suppressed, so an upper limit for the pixel value may be set so that the pixel value is equal to or less than a certain value.

[0082] (Variation 4) A fourth modification of the image processing device 200 will be described. This modification reduces the pixel value of the K plate according to print medium information.

[0083] Fig. 17 is a diagram showing an example of the configuration of a show-through prevention unit according to Modification 4. As shown in Fig. 17, the image processing unit 260 further includes a print medium information acquisition unit 264 as a means for suppressing show-through.

[0084] The print medium information acquisition unit 264 acquires print medium information such as the thickness of the print medium or the infrared light transmittance. For example, a table showing the print medium type, print medium thickness, and infrared light transmittance is stored in the memory of the image processing device 200, and the print medium information acquisition unit 264 loads information from the table in response to the user's selection of the print medium type. Note that the print medium type, print medium thickness, or infrared light transmittance may be acquired by an infrared sensor or paper thickness sensor provided outside the image processing device 200.

[0085] Several pixel value correction patterns are prepared according to, for example, the thickness of the printing medium, and the latent back side image correcting unit 263-1 selects one according to the printing medium information.

[0086] Fig. 18 is a diagram showing an example of a latent image show-through suppression processing flow performed by the image processing device 200 according to Modification 4. The flow shown in Fig. 18 is obtained by replacing the processing of S32 in the flow shown in Fig. 15 with S33. The image processing device 200 executes processing to reduce the pixel value of the K plate in accordance with the print medium information (S33), and ends this latent image show-through suppression processing.

[0087] 19 is a diagram showing an example of conversion of pixel values ​​of the K plate performed by the image processing device 200. As an example, conversion examples are shown for three cases where the print medium is thick, medium, and thin. If the print medium is thin, show-through is more likely to occur when the latent image is read, so the pixel value of the back side image is set lower, that is, the print density is set lighter.

[0088] When the print medium information is infrared light transmittance, the higher the infrared light transmittance of the print medium, the more likely it is that the latent image will show through when it is read. Therefore, the backside print density is set to be lighter.

[0089] Furthermore, this latent image show-through suppression process is just one example, and a simple process of whether or not to execute a process for lowering the pixel value of the K plate according to print medium information may be used.

[0090] (Variation 5) A fifth modified example of the image processing device 200 will be described.

[0091] Fig. 20 is a diagram showing an example of the configuration of a show-through prevention unit according to Modification 5. As shown in Fig. 20, the image processing unit 260 has a toner save correction processing unit 265 as a means for suppressing show-through.

[0092] The toner save correction processing unit 265 performs toner save correction on the image of the processing page in response to an instruction to execute correction. Toner save correction refers to image correction that lowers the pixel value of the image to lower the print density in order to suppress the amount of toner consumption, and is a function that is also provided in general image forming devices.

[0093] Fig. 21 is a diagram showing an example of a flow of a latent image show-through prevention process performed by the image processing device 200. The flow shown in Fig. 21 is obtained by replacing the process of S3 shown in Fig. 12 with S34. The image processing device 200 instructs the toner save correction processing unit 265 to execute correction as show-through prevention processing (S34), and ends this latent image show-through prevention processing.

[0094] In this way, by using the toner save correction, it is possible to reduce the pixel value correction table dedicated to suppressing show-through.

[0095] (Variation 6) A sixth modified example of the image processing device 200 will be described. Fig. 22 is a diagram showing an example of the configuration of a show-through suppression unit according to Modification Example 6. As shown in Fig. 22, the image processing unit 260 has a latent image show-through suppression processing unit 263 having a latent image back-side object extraction unit 263-2 and a latent image back-side image correction unit 263-3 in the latent image show-through suppression processing unit 263 as means for suppressing show-through.

[0096] The latent image back surface object extraction unit 263-2 compares the coordinates of the latent image with the object coordinates of the latent image back surface page, and extracts a latent image back surface object on the back surface that corresponds to the latent image area.

[0097] The latent back image correcting unit 263-3 executes latent back image correction processing on the extracted object.

[0098] Fig. 23 is a diagram showing an example of a flow of a latent image show-through suppression process performed by the image processing device 200. The flow shown in Fig. 23 replaces the process of S3 shown in Fig. 12 with S35 and S36. As the show-through suppression process, the image processing device 200 extracts a latent image back surface object (S35), executes a latent image back surface image correction process for the extracted object (S36), and ends this latent image show-through suppression process.

[0099] Fig. 24 is a diagram showing an example of the effect of the latent image show-through suppression process of Modification Example 6. Fig. 24 shows a comparison example between the correction process for the entire back page and the correction process for an extracted object. In the example shown in Fig. 24, the back page of the latent image contains two types of images of the K plate. One is a gradation image, and the other is an image of the characters "aiu".

[0100] When image correction is performed on the entire back page, the density of both the gradation image and the character image of "aiu" are suppressed. On the other hand, when the object in the area of ​​the back page corresponding to the latent image (the latent image back area surrounded by the dotted line), that is, the character "aiu", is extracted and image correction is performed on only that area, the objects in other areas, in this example the gradation image, can be printed with their original density.

[0101] As described above, if there is a gradation image on the K version of the back page, reducing the density reduces the gradation and significantly changes the appearance of the image, leading to a decrease in image quality. By limiting the processing to the back area of ​​the latent image, the decrease in image quality can be prevented.

[0102] The suppression process is not limited to a method of reducing the density. Here, too, the black K image may be replaced with a CMY K image and printed. In this modified example, the objects to be corrected are limited, so the number of objects to be replaced with the CMY K image is reduced, and the amount of CMY toner consumed can be suppressed.

[0103] (Variation 7) A seventh modified example of the image processing device 200 will be described.

[0104] Fig. 25 is a diagram showing an example of the configuration of a show-through prevention unit according to Modification 7. As shown in Fig. 25, the image processing unit 260 has a latent image show-through prevention processing unit 263 having a latent image show-through notification processing unit 263-4.

[0105] When latent image show-through occurs, the latent image show-through notification processing unit 263-4 notifies the user of the occurrence of latent image show-through through a user interface. Here, the user interface is, for example, a monitor, speaker, or warning lamp of a PC that has sent print data to the image processing device, or an operation panel, speaker, or warning lamp of an image forming device to which the raster data is sent.

[0106] If the printer is a PC monitor or an operation panel with a monitor, the user is warned by a warning display on the monitor. If the printer is a speaker, a warning sound is emitted, and if the printer is a warning lamp, a warning light is turned on. By warning the user, the user can be encouraged to stop double-sided printing or to reconsider the print layout, which can result in the prevention of latent image bleed-through.

[0107] Fig. 26 is a diagram showing an example of a flow of a latent image show-through suppression process performed by the image processing device 200. The flow shown in Fig. 26 is obtained by replacing S3 with S4 in the flow shown in Fig. 9. When S1 (Yes) or S2 (Yes) is satisfied, the image processing device 200 issues a notification instruction that latent image show-through will occur (S4).

[0108] (Variation 8) An eighth modified example of the image processing device 200 will be described.

[0109] 27 is a diagram showing an example of the configuration of a show-through prevention section according to Modification 8. As shown in FIG.

[0110] The latent image adding unit 266 adds a latent image to the print data according to, for example, the latent image background image, latent image, and latent image position set by the user. The user may also select the latent image background image and information to be embedded as a latent image (character information to be converted into a QR code) from the object of the print data. Since the latent image adding unit 266 acquires the latent image information from the user settings, in this configuration the latent image adding unit 266 also functions as the latent image information acquiring unit, eliminating the need to provide a separate latent image information acquiring unit.

[0111] Although several embodiments and modifications of the present invention have been described above, these embodiments and modifications are presented as examples and are not intended to limit the scope of the invention. These novel embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. Each of these embodiments and modifications is included in the scope and gist of the invention, and is included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0112] 100 Image forming device 260 Image Processing Unit 261 Print information acquisition section 262 Latent image information acquisition unit 263 Latent image back-bleed suppression processing unit 270 RIP Processing Unit 300 client PCs 400 Print Server 500 Network [Prior art documents] [Patent documents]

[0113] [Patent Document 1] JP 2018-024127 A

Claims

1. a print information acquisition unit that acquires print information from the print data; a latent image information acquiring unit for acquiring latent image information from the printing data; a latent image show-through prevention processing unit that performs show-through prevention processing when the printing information is set to double-sided printing and a latent image is included in an object of the printing data, a color material of the latent image is a color material that is read in a latent image reading wavelength range of the latent image that is different from a reading wavelength range of a visible image after printing; The show-through suppression process is a process for correcting the settings of the color materials of an image to be printed on the reverse side of the printing surface on which the latent image is printed. Image processing device.

2. A print medium information acquisition unit that acquires print medium information is further provided, The latent image show-through suppression processing unit performs the show-through suppression processing in accordance with the print medium information acquired by the print medium information acquisition unit. The image processing device according to claim 1 .

3. The back-reflection suppression processing comprises: A correction process for lowering the pixel value of the image on the back surface printed with toner that exhibits light absorption in the latent image reading wavelength range.

3. The image processing device according to claim 1 or 2.

4. The back-reflection suppression processing comprises: Toner saving is a process for reducing the density of the image on the back side printed with toner that exhibits light absorption in the latent image reading wavelength range.

3. The image processing device according to claim 1 or 2.

5. The back-reflection suppression processing comprises: A process of replacing the K (black) plate image of the image on the back surface printed with a toner that exhibits light absorption in the latent image reading wavelength range with a black image of C (cyan), M (magenta), and Y (yellow) plates.

3. The image processing device according to claim 1 or 2.

6. The latent image back-transmission suppression processing unit includes: When an object is present in a corresponding area on the back surface corresponding to a latent image area on the printing surface on which the latent image is printed, the show-through suppression process is performed. The image processing device according to any one of claims 1 to 5.

7. The latent image back-transmission suppression processing unit includes: a notification processing unit that notifies of latent image show-through when the printing information is set to double-sided printing and the latent image is included in an object of the printing data; The image processing device according to any one of claims 1 to 6.

8. The latent image information acquisition unit includes a latent image addition unit that acquires latent image information including a latent image of a latent image set by a user, a visible image in which the latent image is embedded, and a latent image area, and adds the latent image to the printing data. The image processing device according to any one of claims 1 to 7.

9. The latent image adding unit sets an area selected from a print preview screen of the print data as a latent image area, and further generates a latent image embedded image by embedding a latent image corresponding to an object located in the selected latent image area in a visible image. The image processing device according to claim 8.

10. The image printed on the back surface is readable in both the visible image and the latent image in their respective reading wavelength ranges. The image processing device according to any one of claims 1 to 9.

11. An image processing device according to any one of claims 1 to 10; an image forming unit that performs double-sided printing on the printing data based on the setting of the color material after the image processing device performs the show-through suppression processing; An image forming apparatus comprising:

12. An image processing method performed by an image processing device, comprising: acquiring print information from the print data; acquiring latent image information from the printing data; performing a process of suppressing show-through when the printing information is set to double-sided printing and a latent image is included in an object of the printing data; Including, a color material of the latent image is a color material that is read in a latent image reading wavelength range of the latent image that is different from a reading wavelength range of a visible image after printing; The show-through suppression process is a process for correcting the settings of the color materials of an image to be printed on the reverse side of the printing surface on which the latent image is printed. Image processing methods.

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