JP2021039197A - Image formation device, method for controlling the same, and program - Google Patents

Abstract

To attain a normal concentration while limiting the total toner amount per unit area within a defined value in a configuration of processing image data with the number of colors beyond four by using a plurality of image processing chips.SOLUTION: The information of a toner applied amount of a color processed by another chip is added to attribute data of a packet processed by an own chip. After that, processing of limiting the toner applied amount of the own chip is performed with the toner applied amount of the color processed by another chip taken into consideration.SELECTED DRAWING: Figure 9

Description

The present invention relates to an image forming apparatus capable of printing using at least one special color in addition to the process color.

Digital printing technology has been increasing its utility value in recent years in the on-demand printing market and the small number of document printing market. In particular, full-color printing using electrophotographic technology is superior to other printing technologies in terms of productivity, printing cost, ease of maintenance, etc., and is expanding the market. Under such circumstances, in addition to the four basic colors of CMYK called process colors, a multicolor printing technology that forms an image using a special color toner that is difficult or impossible to express with these four basic colors has been studied. There is. Examples of the special color toner include a corporate color toner dedicated to a specific user, a clear toner that gives gloss to a printed image, a white toner for decoration, and a gold / silver toner.

In the above electrophotographic technology, there is a so-called toner loading amount limit. This means that the total amount of toner loaded per unit area must be controlled to be less than or equal to the specified value. If it exceeds the specified value, the toner cannot be fixed well on the printing paper, leading to deterioration of print quality. In this regard, Patent Document 1 discloses a technique for obtaining a difference amount between a specified value of the total toner amount and the total value of each toner amount of CMYK, and using the clear toner amount as the difference amount. According to the technique of Patent Document 1, even when clear toner is used in addition to CMYK toner, it is possible to control the total toner amount so as not to exceed a specified value.

Japanese Unexamined Patent Publication No. 2007-11028

An image forming apparatus capable of full-color printing uses an image processing controller with an image processing chip incorporated therein to perform various image processing for printing on image data for each color plate (hereinafter referred to as "print image processing"). To do. In the case of an image forming apparatus for general offices that uses four colors of CMYK, the image processing chip incorporated in the image processing controller also supports up to four colors. When it comes to an image forming apparatus for the on-demand printing market with a number of colors exceeding four, an image processing controller incorporating an image processing chip capable of corresponding to the number of colors is required. Here, it is conceivable to use a plurality of image processing chips capable of supporting up to four colors for general offices to support a number of colors exceeding four colors. According to this method, it is not necessary to develop a dedicated image processing chip capable of handling more than four colors, but there is a problem. First, even if the toner loading amount limit is controlled separately for each image processing chip, there is a possibility that the specified value will be exceeded when the total is applied. Further, if the specified value in charge of one image processing chip is suppressed so as not to exceed the specified value of the toner loading amount limit in total, a normal density may not be obtained.

The image processing controller according to the present disclosure is an image processing controller for forming an image by an electrophotographic method using image data having a number of colors exceeding four colors, and is an image processing controller having an image data having a number of colors exceeding four colors. Among them, the first image processing chip that processes the image data of a predetermined number of colors and the image data of the remaining number of colors excluding the image data of the predetermined number of colors among the image data of the number of colors exceeding the four colors are used. The second image processing chip to be processed, the first loading amount information indicating the toner loading amount to be used for image formation of the image data of the remaining number of colors processed by the second image processing chip, and A generation means for generating second loading amount information indicating the toner loading amount used for image formation of the image data of the predetermined color number processed by the first image processing chip, and the first image. The first loading amount information is added to the image data of the predetermined number of colors processed by the processing chip, and the image data of the remaining number of colors processed by the second image processing chip is subjected to. The first image processing chip includes an additional means for adding the second load amount information, and the first image processing chip is based on the first load amount information added to the image data of a predetermined number of colors. The first loading amount limiting process for the toner having a predetermined number of colors is performed, and the second image processing chip performs the remaining loading amount information based on the second loading amount information added to the image data of the remaining number of colors. It is characterized in that a second loading amount limiting process is performed on the toner having the same number of colors.

According to the technique of the present disclosure, in a configuration in which image data having more than four colors is processed by using a plurality of image processing chips, the total toner amount per unit area is kept within a specified value, and the normal density is maintained. It can be controlled to come out.

Block diagram showing an example of hardware configuration of MFP The figure which shows the internal structure of the image forming part Block diagram showing the internal configuration of the main controller Block diagram showing the internal configuration of the system control unit (A) and (b) are diagrams showing the structure of packets flowing through the ring bus. Diagram showing the internal structure of the DFE interface (A) is a diagram showing the internal configuration of the print processing unit, and (b) is a diagram showing the internal configuration of the printer image processing unit. Flowchart showing the general flow of image processing in the main controller Flowchart showing the flow of packet editing processing in the system control unit Flowchart showing the flow of processing to generate special color loading amount information The figure which shows an example of the toner loading amount conversion table Flowchart showing the flow of print image processing Flowchart showing the flow of print image processing Flowchart showing the flow of toner loading amount limiting processing The figure which shows an example of the loading amount limit value according to the value of attribute data. Flowchart showing the flow of toner loading amount limiting processing

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. It should be noted that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential for the means for solving the invention.

[Embodiment 1]
<Hardware configuration>
FIG. 1 is a block diagram showing an example of a hardware configuration of an MFP (Multi Function Printer) as an image forming apparatus according to the present embodiment. The MFP 100 includes a scanner unit 110, a main controller 120, an operation unit 130, and a printer unit 140.

The scanner unit 110 has a function of optically reading a document and converting it into image data. The scanner unit 110 includes a document conveying unit 102 including a belt or the like for conveying a document, a document reading unit 103 including a laser light source or a lens for optically reading a document, and a scanner control unit 101 for controlling them. ..

The printer unit 140 has a function of transporting a recording medium (paper) and printing image data on the recording medium (paper) as a visible image. The printer unit 140 is an image forming unit 142 that forms a toner image corresponding to image data on paper by an electrophotographic method, a transfer fixing unit 143 that transfers and fixes the formed toner image on paper, and a printed paper. It is composed of a paper ejection unit 144 that performs finishing processing such as sorting and carries it out of the machine, a paper feeding unit 145 that feeds paper, and a printer control unit 141 that controls them.

The main controller 120 is electrically connected to the scanner unit 110 and the printer unit 140, and is further connected to a network 150 such as a LAN, ISDN, or the Internet / intranet. When the user uses the copy function, the main controller 120 controls the scanner unit 110 to acquire the image data of the original, and controls the printer unit 140 to print the image on paper and output it. Further, when the scanning function is used, the scanner unit 110 is controlled to acquire the image data of the original, convert it into code data, and transmit it to the host PC 160 or the like via the network 150. When using the print function, the print data (code data) received from the host PC 160 or DFE (Digital Front End) 170 via the network 150 is converted into image data, and the printer unit 140 is controlled to print the image on paper. Print and output to. It also has a fax reception function that receives data from ISDN or the like and prints it, and a fax transmission function that transmits scanned data to ISDN or the like. Further, the execution instruction of the process in each of these functions is called a job, and the MFP 100 executes a predetermined process according to the job corresponding to each function.

The operation unit 130 is a user interface for the user to perform an input operation, and is composed of, for example, a touch panel and various buttons.

The DFE170 is, for example, a printer server. The DFE 170 communicates with the main controller 120 via the network 150 to control image formation in the printer unit 140. The DFE 170 receives a print job composed of a language such as PDL (Page Description Language) from the PC 160 via the network 150 and converts it into image data.

<Details of image forming part>
FIG. 2 is a diagram showing an internal configuration of the image forming unit 142. The operation of image formation in the electrophotographic method will be described with reference to FIG. Here, as an example, the configuration is such that a total of 6 colors can be supported by adding 2 special colors to the 4 CMYK process colors.

The image forming unit 142 has six photosensitive drums and can form a full-color image using an intermediate transfer body. Each process unit P (Pa, Pb, Pc, Pd, Pe, Pf) that forms an image of each color of cyan, magenta, yellow, black (C, M, Y, K) and special colors (S ₁ , S _2). The photosensitive drums 1 (1a, 1b, 1c, 1d, 1e, 1f) are arranged in each of the above. Each photosensitive drum is rotatable in the direction of the arrow. Around each photosensitive drum 1 (1a, 1b, 1c, 1d, 1e, 1f), a corona charger 2 (2a, 2b, 2c, 2d, 2e, 2f) as a primary charging means, and an exposure device 3 (3a, 3b, 3c, 3d, 3e, 3f) and the developing device 4 (4a, 4b, 4c, 4d, 4e, 4f) are sequentially arranged. Further, cleaners 6 (6a, 6b, 6c, 6d, 6e, 6f) are arranged along the rotation direction of the photosensitive drum 1. The process unit P includes a photosensitive drum 1 as an image carrier that is rotatably supported. The photosensitive drum 1 has a support shaft at the center, and is rotationally driven in the direction of arrow R1 around the support shaft. The corona charger 2 uniformly and uniformly charges the surface of the photosensitive drum 1 to a predetermined polarity and potential.

The exposure apparatus 3 scans while turning off / on the laser beam corresponding to the image data to form an electrostatic latent image on the irradiated photosensitive drum 1. The developing apparatus 4 develops the toner by adhering it to the exposed portion of the electrostatic latent image by the magnetic brush in the developing region, and forms the toner image on the photosensitive drum 1. The intermediate transfer unit 5 includes an intermediate transfer belt 51, a transfer roller 53 (53a, 53b, 53c, 53d, 53e, 53f), a secondary transfer roller 56, 57, and an intermediate transfer belt cleaner 55.

The toner images of each color formed on the photosensitive drum 1 (1a, 1b, 1c, 1d, 1e, 1f) are sequentially transferred onto the intermediate transfer belt 51 by the primary transfer unit N1, and the secondary transfer unit rotates as the belt rotates. It is transported to N2. Further, the paper taken out from the cassette is supplied to the transport roller, and the toner image described above is transferred onto the paper at the secondary transfer unit N2. Then, the fixing means (not shown) fixes the toner on the paper by pressurizing and heating at pressure and temperature, and a full-color image is formed. Each process means acting on the photosensitive drum 1 is controlled by the printer control unit 141.

As described above, in order to normally fix the toner on the paper, it is necessary to control the amount of toner per unit area on the paper to be equal to or less than the specified value (toner loading amount limit).

<Details of main controller>
FIG. 3 is a block diagram showing an internal configuration of the main controller 120. The main controller 120 as an image processing controller is composed of two image processing chips 200, 201, a ring bus 202, a ROM 290, a RAM 270, 271, 291 and an HDD 292, a PHY293, and a DFE interface 294. Hereinafter, each part will be described in detail. In this embodiment, the image processing chips 200 and 201 are independent 1-chip LSIs (Large-Scale Integrated Circuits). Further, in the present embodiment, the image processing chips 200 and 201 can each support a maximum of four colors and have the same configuration. Hereinafter, each part constituting the main controller 120 will be described.

First, the image processing chip 200 will be described. The image processing chip 200 includes a system control unit 210, a ring bus switch 220, a print processing unit 230, a loopback processing unit 240, a scan processing unit 250, a RAM controller 260, and a ring bus external interface 280. The system control unit 210 is a control module that controls the scan process in the scanner unit 110 and the print process in the printer unit 140. The system control unit 210 is connected to the ring bus switch 220 by the ring bus 202, and controls the transfer of image data used in the scan process and the print process via the ring bus switch 220. Further, the system control unit 210 comprehensively controls the entire system such as data transmission to the network 150 via PHY293, data reception from the network 150, and display processing to the operation unit 130.

The ring bus switch 220 controls the switch of the ring bus 202 for transferring image data to each module in the main controller 120. In the present embodiment, buses for transferring image data to each module in the main controller 120 are connected in a ring shape via a ring bus switch 220. As a result, image data can be exchanged between the system control unit 210, the print processing unit 230, the loopback processing unit 240, the scanning processing unit 250, and the ring bus external interface 280. The ring bus switch 220 is controlled by a ring bus switch setting unit (not shown), and the connection destination of each module on the ring bus 202 can be changed as needed.

The print processing unit 230 performs print image processing such as color space conversion processing and halftone processing for obtaining print data used for printing processing in the printer unit 140. The print processing unit 230 receives the image data from the ring bus switch 220, performs the above-mentioned image processing for printing on the image data, and outputs the processed image data to the printer unit 140.

The loopback processing unit 240 performs editing-type image processing that may be used in both print processing and scanning processing. The loopback processing unit 240 receives image data from the system control unit 210 via the ring bus 202, performs the above-mentioned editing system image processing, and transfers the processed image data to the system control unit 210 via the ring bus 202. return.

The scan processing unit 250 performs scanner image processing such as shading correction processing and filter processing on the image data acquired by the scanner unit 110. The scan processing unit 250 performs scanner image processing on the image data transferred from the scanner unit 110, and transfers the processed image data to the ring bus switch 220. The image data transferred to the ring bus switch 220 is transferred to the system control unit 210 via the ring bus 202.

The RAM controller 260 performs a process of writing the image data received from the print processing unit 230, the loopback processing unit 240, and the scan processing unit 250 to the RAM 270, or reading and transferring the image data written to the RAM 270. The print processing unit 230, the loopback processing unit 240, and the scan processing unit 250 use the RAM 270 as a temporary image buffer to execute the image processing in charge of each.

The ring bus external interface 280 is an interface that connects the image processing chip 200 centered on the ring bus switch 220 and the outside to input and output packets, which will be described later. Data is transferred between the image processing chip 200 and the image processing chip 201 via the ring bus external interface 280. That is, in the present embodiment, the image processing chip 201 is connected to the image processing chip 200 via the ring bus external interface 280 to form one ring bus 202.

Next, the image processing chip 201 will be described. The image processing chip 201 is a module for executing a print image processing function for special color data on the main controller 120. As described above, in the present embodiment, the configuration of the image processing chip 201 and the configuration of the image processing chip 200 are the same. That is, the image processing chip 201 is composed of a system control unit 211, a ring bus switch 221, a print processing unit 231 and a loopback processing unit 241, a scan processing unit 251, a RAM controller 261 and a ring bus external interface 281. The functions of these parts are the same as the functions of the corresponding parts in the image processing chip 200. By adopting such a configuration, it is possible to suppress the development cost of designing the image processing chip 201 separately from the image processing chip 200. In the present embodiment, among the print processing unit 231, the loopback processing unit 241 and the scan processing unit 251 in the image processing chip 201, the print processing unit 231 is actually used as an extended function. In FIG. 3, the system control unit 211, the loopback processing unit 241 and the scan processing unit 251 are shaded to indicate that they do not need to be operated.

The DFE interface 294 receives the image data (PDL data) to be printed from the DFE 170 and generates packets that can be processed by the image processing chips 200 and 201. The generated packet is stored in the RAM 291 or the HDD 292 by the system control unit 210 via the ring bus 202. The details of the packet and the DFE interface 294 will be described later.

<Details of system control unit>
FIG. 4 is a block diagram showing an internal configuration of the system control unit 210. Hereinafter, each element constituting the system control unit 210 will be described. The system control unit 211 in the image processing chip 201 has the same configuration.

The CPU 310 is a processor that controls the entire system. The CPU 310 comprehensively controls job processing such as print processing and scan processing according to the OS and control program deployed in the RAM 291.

The ROM controller 320 is a control module for accessing the ROM 290 that stores the boot program of the system. When the power of the MFP 100 is turned on, the CPU 310 accesses the ROM 290 via the ROM controller 320, and the CPU 310 boots.

The RAM controller 330 is a control module for accessing the RAM 291 in which the system control program and image data are stored. The RAM controller 330 includes a register for setting and controlling the RAM 291, and this register can be accessed from the CPU 310.

The operation unit interface 340 controls the reception of operation instructions by the user to the operation unit 130 and the display of operation results.

The HDD 292 stores system software, application programs, image data, page information and job information corresponding to each image data. The HDD 292 is connected to the system bus 300 via the HDD controller 360, and writes and reads data according to the instructions of the CPU 310.

The LAN controller 370 connects to the network 150 via PHY293 and inputs / outputs information such as image data to and from an external host computer.

The image compression unit 350 compresses the image data stored in the RAM 291 or the HDD 292 into a compression format such as JPEG. Further, the image stretching unit 351 stretches the image data compressed in a compression format such as JPEG. The rendering unit 352 converts the image data (PDL data) received from the network 150 via the LAN controller 370 into bitmap data that can be handled by the printer unit 140.

The ring bus interface 301 is an interface for connecting the system bus 300 in the system control unit 210 and the ring bus 202 centered on the ring bus switch 220 outside the system control unit 210. The data flowing through the ring bus 202 is called a packet, and the ring bus interface 301 transmits the packet stored in the RAM 291 or the HDD 292 to the ring bus 202. Further, the packet received from the ring bus 202 is stored in the RAM 291 or the HDD 292.

The packet DMA unit 380 receives the packet output by the loopback processing unit 240, the scanning processing unit 250, or the DFE interface 294 via the ring bus 202, and writes the packet to the RAM 291. Further, the packet DMA unit 380 reads the packet from the RAM 291 via the ring bus 202, and transmits the packet to the print processing unit 230, 231 or the loopback processing unit 240. The packet DMA unit 380 has a function of rewriting the header of the packet described later, thereby controlling the forwarding destination of the packet. Further, since the packet DMA unit 380 has a plurality of DMA units, data transfer to a plurality of image processing modules can be executed in parallel.

<Packet structure>
FIGS. 5A and 5B are diagrams showing the structure of a packet flowing through the ring bus 202. The packet 600 is composed of a header unit 610 and a data unit 620. FIG. 5A shows the internal structure of the header unit 610, which is divided into packet type 601, chip ID 602, page ID 603, job ID 604, packet Y coordinate 605, packet X coordinate 606, packet byte length 607, and data byte length 608. .. Hereinafter, each element constituting the header portion 610 will be described.

Packet type 601 indicates whether the packet is image data or command data. When the packet type 601 indicates image data, the image data is stored in the data unit 620. When the packet type 601 indicates command data, the data unit 620 stores a setting address and a setting value for setting the coefficient and mode of each image processing unit.

The chip ID 602 indicates an ID (identifier) for identifying a processing unit that is a target for transmitting a packet. For example, ID "0" of the image processing chip 200 is the print processing unit 230, ID "1" is the loopback processing unit 240, ID "2" is the scan processing unit 250, and ID "3" is the print processing of the image processing chip 201. It is a part 231 and so on.

Page ID 603 indicates the page number to which the packet belongs. Processing such as scanning and printing may be performed on a plurality of pages, and indicates which page the packet belongs to in that case.

The job ID 604 indicates the job number to which the packet belongs. For example, a job number is assigned to a packet of a print job containing only process colors, "job number 1" is assigned to a packet of a multicolor print job containing special colors, and so on, and each job is identified. Is possible.

The packet Y coordinate 605 indicates at which Y coordinate in the page the image data is located when the image data is stored in the data unit 620. Further, the packet X coordinate 606 indicates at which X coordinate in the page the image data is located when the image data is stored in the data unit 620. The image data stored in the data unit 620 is obtained by dividing the image data for each page into a rectangular size having a predetermined number of pixels (for example, 32 pixels × 32 pixels). Therefore, when the page data is reconstructed from the packet, these Y-coordinate and X-coordinate data are referred to. The image data is compressed by the image compression unit 350 or a compressor mounted inside each image processing unit, and is stored in the data unit 620 as compressed image data.

The packet byte length 607 indicates the total number of bytes of the packet, and the data byte length 608 indicates the total number of bytes of the data unit 620.

FIG. 5B shows the internal structure of the data unit 620, which is composed of pixel data 621 and attribute data 622. The pixel data 621 shows each pixel value of the 32 × 32 pixel rectangular image data included in the data unit 620. Further, the attribute data 622 indicates the attribute value of each pixel in the rectangular image data of 32 × 32 pixels included in the packet. Attribute data is information consisting of 8 bits. First, the object attribute is indicated by the two bits of bit0 and bit1. The object attribute is "00" for an image, "10" for a graphic, "01" for a line, and "11" for a character. Next, bit2 indicates the background attribute, and "1" is stored when the object is the background part. Further, bit3 indicates a high-definition character processing flag, and "1" is stored when the object is a high-definition character. The remaining 4 bits from bit 4 to bit 7 have conventionally been empty bits that do not indicate information. In the present embodiment, information on the amount of toner loaded is assigned to two of these empty bits, bit4 and bit5 (details will be described later).

Various image processing units inside the image processing chip can control to change the content of image processing to the target pixel by referring to a desired bit of this attribute data.

The packet as described above flows on the ring bus 202. Each image processing unit receives and interprets the packet, and can transfer the packet according to the chip ID of each packet and perform predetermined image processing.

<Details of DFE>
FIG. 6 is a diagram showing an internal configuration of the DFE interface 294. Hereinafter, each element constituting the DFE interface 294 will be described.

The image input unit 501 receives the PDL data transmitted from the DFE 170, and the image data in raster order divided into the process colors C, M, Y, K and the special colors S ₁ and S _2. To generate.

The raster packet conversion unit 502 converts the raster image data of each color plate input from the image input unit 501 into rectangular image data of 32 pixels × 32 pixels. Since the image data in the packet is a rectangular unit of 32 pixels × 32 pixels, it is converted into a rectangle for packet transmission in the subsequent stage.

The image compression unit 503 compresses the image data input from the raster packet conversion unit 502 and outputs it to the packet input / output I / F 504 in the subsequent stage.

The packet input / output I / F 504 is an interface between the DFE interface 294 and the ring bus 202 centered on the ring bus switch 220. The packet input / output I / F 504 is composed of a packet input unit 505 and a packet output unit 506.

The packet output unit 506 outputs the packet input from the image compression unit 503 to the ring bus 202. The output packet is temporarily stored in the RAM 291 by the packet DMA unit 280 in the system control unit 210, then transferred from the RAM 291 to the HDD 292 by the HDD controller 360 and spooled.

The packet input unit 505 receives the packet via the ring bus 202, refers to the chip ID in the header of the packet, and checks whether it is the same as the chip ID assigned to itself. If the chip ID in the header of the received packet is different from the chip ID assigned to itself, it is determined that the packet should not be processed by itself, and the packet is transferred to the packet output unit 506. At this time, since the image data for the DFE interface 294 is input only from the DFE 170, the packet of the image data to be processed by itself is not received.

<Details of print processing unit>
FIG. 7A is a diagram showing an internal configuration of the print processing unit 230. The packet input / output I / F 400 is an interface between the print processing unit 230 and the ring bus 202 that connects the ring bus switch 220. The packet input / output I / F 400 is composed of a packet input unit 404 and a packet output unit 405.

The packet input unit 404 receives the packet via the ring bus 202, refers to the chip ID in the header of the packet, and checks whether it is the same as the chip ID assigned to itself. If the chip ID in the header of the received packet is different from the chip ID assigned to itself, it is determined that the packet should not be processed by itself, and the packet is transferred to the packet output unit 405. On the other hand, when the received ID is the same as the chip ID assigned to itself, the image data of the packet is transferred to the image stretching unit 401, and the print image processing is executed.

The packet output unit 405 transfers the packet of the other chip ID transferred from the packet input unit 404 to the ring bus 202.

The image stretching unit 401 stretches the compressed image data received from the packet input / output I / F 400 and restores the image processing in the subsequent stage to a state in which it can be performed.

The packet raster conversion unit 402 receives the decompressed image data from the image decompression unit 401 and converts it into raster image data. As described above, the image data in the packet is data in a rectangular unit of 32 pixels × 32 pixels. In the case of an electrophotographic image forming apparatus, the printing process in the printer unit 140 is performed in raster order (line order), so the packet raster conversion unit 402 converts the arrangement of pixels of the image data in raster order. There is.

The printer image processing unit 403 receives the image data converted in raster order from the packet raster conversion unit 402, and performs image processing on the image data as a preprocessing of the printing process in the printer unit 140. FIG. 7B is a diagram showing the internal configuration of the printer image processing unit 403. The color space processing unit 406 executes color space conversion processing according to the toner color used by the printer unit 140 on the raster image data input from the packet raster conversion unit 402. At this time, the attribute data is referred to in pixel units, and the color space conversion of each color plate data of _{C, M, Y, K, S 1} and S _{2 is performed as necessary with the parameters corresponding to the attribute data.} If the color space conversion process is unnecessary, it is passed through.

The loading amount limiting processing unit 407 performs processing for limiting the toner loading amount on the image data of each color plate output from the color space processing unit 406. The loading amount limiting process includes a base removal process and a rate reduction process. The base removal process is a process of converting the toner loading amount of each CMY color with respect to the process color into the toner loading amount of K single color. The same rate reduction process is a process of reducing the amount of toner loaded in each color at the same rate with respect to the special color and the process color. By these processes, the total toner loading amount including the toner loading amount of the process color and the toner loading amount of the special color per unit area is controlled to be less than the specified value of the preset loading amount limit. .. The specified value, which is a threshold value for how much the toner loading amount should be reduced, can be changed by the attribute data.

The halftone processing unit 408 performs halftone processing on the raster image data of each color plate whose toner loading amount has been restricted, which is input from the loading amount limiting processing unit 407. Halftone processing includes screen processing and error diffusion processing. The screen processing is a method of applying a predetermined dither matrix to the input raster image data and converting it into an N value. Further, in the error diffusion processing, the pixel value of the pixel of interest in the input raster image data is converted into an N value by comparing it with a predetermined threshold value, and the difference between the pixel value and the threshold value at that time is converted into an N value thereafter. It is a process of spreading the image. Further, the halftone processing unit 408 refers to the attribute data on a pixel-by-pixel basis, and can select screen processing or error diffusion processing according to the attribute data.

The inter-drum delay control unit 409 controls reading and writing of raster image data of each color plate to the RAM 270 or 271. At the time of image formation, it is necessary to adjust the printing timing of each color plate by the time corresponding to the drum interval of the photosensitive drum 1 of each color at the paper transport speed (called the print engine speed). Therefore, the inter-drum delay control unit 409 _{temporarily buffers the raster image data of each color of C, M, Y, K, S 1} and S _{2 in} the RAM 270 or 271, and print timing according to the inter-drum distance of each color. Reads the image data and outputs it to the printer unit 140.

<Image processing in the main controller>
FIG. 8 is a flowchart showing a rough flow of image processing in the main controller 120 according to the present embodiment. Of the following steps, steps 801 to 803 are executed by the DFE interface 294, and steps 804 and 805 are executed by the system control unit 210 in the image processing chip 200. Then, step 806a and step 807a are executed by the print processing unit 230 in the image processing chip 200, and steps 806b and 807b are executed by the print processing unit 231 in the image processing chip 201. Hereinafter, description will be given according to the flow of FIG.

In step 801 the DFE interface 294 contains PDL data including a color image represented by four basic process colors (C, M, Y, K) and two special colors (S ₁ , S _{2) and their attribute data.} Is input from DFE170. In the following step 802, the raster image data is generated by the RIP process, and further divided into the raster image data of _{the CMYK page and the raster image data of the S 1} S _{2 page.} Then, in step 803, two types of packets are generated. Specifically, a "CMYK + Z" packet is generated from the process color image data and its attribute data (hereinafter referred to as "Z"), and further, "CMYK + Z" packet is generated from the special color two-color image data and its attribute data. A packet of "S ₁ S ₂ + Z" is generated. The packet is as described with reference to FIG.

In step 804, the system control unit 210 in the image processing chip 200 executes a process of spooling each of the two types of packets generated in step 803 to the HDD 292. In the following step 805, the packet stored in the HDD 292 is expanded in the RAM 291 by the spool process, and the packet editing process (hereinafter, referred to as “packet editing process”) is executed. In this packet editing process, the attribute data included in the packet is edited. As described above, in the attribute data in the PDL data sent from DFE170, bits 4 to 7 are unused bits. Therefore, in the present embodiment, the toner loading amount information is embedded in bit 4 and bit 5 of these unused bits. The embedded toner loading amount information is information on the toner loading amount in the "other packet" having the same coordinates in the image to be printed. For example, information on the amount of toner loaded in a special color is embedded in the attribute data of a packet of a process color. In addition, information on the amount of toner loaded in the process color is embedded in the attribute data of the packet of the special color. That is, by including the information on the toner loading amount of the color processed by the other chip in the attribute data of each packet, the color processed by the other chip when the toner loading amount limiting processing is performed on the own chip. The amount of toner loaded can be grasped. As a result, it becomes possible to appropriately execute the toner loading amount limiting process on each image processing chip. Before executing the packet editing process, the attribute data of the packet of the process color and the attribute data of the packet of the special color are common (same content). After the packet editing process is executed, the attribute data bit4 and bit5 contain information on the amount of toner loaded in the color processed by the other image processing chip, so that the contents are different from each other. Here, the attribute data of the edited packet of the process color is referred to as "Z _P ", and the attribute data of the edited packet of the special color is referred to _{as "Z S".} Then, the edited packet is compressed by the image compression unit 350 and then spooled again in the HDD 292. The details of the attribute data in the edited packet will be described later.

Steps 806a and 807a executed by the print processing unit 230 in the image processing chip 200 and steps 806b and 807b executed by the print processing unit 231 in the image processing chip 201 are processed in parallel. ..

First, in step 806a, _{the compressed packet of "CMYK + Z P} " is read from the HDD 292, decompressed by the image decompressing unit 401 in the print processing unit 230, and then rasterized by the packet raster conversion unit 402. Will be executed. As a result, raster image data of _{"CMYK + Z P" is generated.} Then, in step 807a, a series of print image processing such as color space conversion processing, toner loading amount limiting processing, and halftone processing is executed by the printer image processing unit 403 in the print processing unit 230. The process color (CMYK) print data thus obtained is output to the printer unit 140, and the main process is completed.

On the other hand, in step 806b, _{the compressed packet of "S 1} S ₂ + Z _S " is read from the HDD 292, decompressed by the image decompression unit 401 in the print processing unit 231 and then decompressed by the packet raster conversion unit 402. Rasterize processing is executed. As a result, raster image data of _{"S 1} S ₂ + Z _{S" is generated.} Then, in step 807b, a series of print image processing such as color space conversion processing, toner loading amount limiting processing, and halftone processing is executed by the printer image processing unit 403 in the print processing unit 231. _{The print data of the two} special colors (S ₁ S 2) thus obtained is output to the printer unit 140, and this processing is completed.

The above is a rough description of the image processing in the main controller according to the present embodiment. The printer unit 140, which has received the CMYK print data from the print processing unit 230 of the main controller 120 and the print data of S ₁ S ₂ from the print processing unit 231 respectively, executes the print processing as a print image of one page. Become.

In the present embodiment, the toner loading amount information is embedded in the unused bit 4 of the attribute data on the MFP100 side, but this cannot be obtained locally. For example, the DFE170 side may generate PDL data in which toner loading information is embedded in unused bits of attribute data in advance, and the packet editing process in step 805 may be skipped.

Next, among the image processing in the main controller 120 described above, a portion particularly related to the toner loading amount limitation will be described in detail.

<Packet editing process>
FIG. 9 is a flowchart showing the flow of packet editing processing in the system control unit 210. This flowchart is realized by the CPU 310 mounted on the system control unit 210 executing a predetermined control program.

First, in step 901, the system control unit 210 in the image processing chip 200 _{spools two types of packets (“CMYK + Z” and “S 1} S ₂ + Z”) received from the DFE interface 294. The following steps 902 to 909 correspond to the packet editing process described above, and the contents thereof are described in detail. Hereinafter, each step will be described.

In step 902, it is determined whether or not the operation mode setting related to the toner loading amount limit is set to the special color priority mode (that is, whether or not the toner loading amount is limited only on the process color side). .. The user specifies a desired operation mode in advance using the operation unit 130 or the like to determine whether the toner loading amount limit is applied to the process color side, the special color side, or both evenly. You just have to keep it. Alternatively, it may be specified in the PDL data sent from DFE170. For example, in the case of using gold and silver as special colors and printing in the special color priority mode, the gold toner and silver toner can be loaded with toner up to the specified value, and how much gold toner and silver toner can be loaded. Depending on the situation, the amount of toner on the process color side will be limited. Then, it may be determined whether or not the special color priority mode is set according to the operation mode specified by the user by the method as described above. As a result of the determination, if the special color priority mode is set, the process proceeds to step 903, and if not, the process proceeds to step 905.

In step 903, a process of generating special color loading amount information (hereinafter, referred to as “special color loading amount information generation processing”) is executed using the spooled special color packet. Here, the special color loading amount information is information indicating how much the special color toner is loaded on the target pixel of interest in total (the total toner loading amount of all the special colors). The details of the special color loading amount information generation processing will be described later.

In step 904, a process of adding the special color loading amount information generated in S903 to the attribute data inside the packet of the process color is executed. Specifically, a process of embedding information indicating the total toner loading amount of the special color is performed using two bits of bit4 and bit5, which are unused bits of the attribute data which is 8-bit data. The details will be described below. First, the total toner loading amount of all special colors calculated by the special color loading amount information generation process is divided into four levels of "0 to 3". Table 1 shows an example of leveling.

In the example of Table 1, if the total toner loading amount is 0%, it is set to "0", if it is 1% to 60%, it is set to "1", if it is 61% to 130%, it is set to "2", and 131% or more. If so, the level is divided into "3". When the leveling of the total toner loading amount is completed, the value (level value) obtained by the leveling is converted into a binary number and stored for bit4 and bit5 of the attribute data. Table 2 shows how the special color loading amount information is added to the attribute data.

As described above, bit information representing the total toner loading amount of the special color is added to the empty bits of the attribute data. The values from bit0 to bit3 remain the same. In the present embodiment, the special color loading amount information is rounded to four levels in order to be expressed by 2 bits, but the special color loading amount information depends on the number of free bits of the attribute data and the content of the toner loading amount limiting process. The number of bits representing the above may be determined. For example, it may be expressed by 4 bits or 1 bit, and the converted value will change accordingly. As the number of bits is increased, the loading amount information can be held in detail, so that the accuracy of the toner loading amount limiting process is improved.

The above-mentioned processing is performed on a pixel-by-pixel basis, and the attribute data to which the special color loading amount information is added is stored in the HDD 292 again. By including the special color loading information in the attribute data in this way, it is possible to grasp how much the special color toner is loaded in total per unit area in the print processing unit 230 in the image processing chip 200 that processes the packet of the process color. Will be.

In step 905, a packet (“CMYK + Z ₁ ”) including process color pixel data and attribute data is sent to the print processing unit 230. When the special color priority mode is specified, the attribute data in the packet transmitted in this step stores information on the total loading amount of the special color toner. On the other hand, the attribute data in the packet transmitted when the special color priority mode is not specified does not include information on the total loading amount of the special color toner (all unused bits have an initial value of 0). It remains stored).

In step 906, it is determined whether or not the mode setting related to the toner loading amount limitation is set to the process color priority mode, that is, whether or not the toner loading amount is limited only for the image on the special color side. For example, in the case of using clear as a special color and printing in the process color priority mode, each CMYK toner can be loaded with toner up to the specified value, and depending on how much each CMYK toner is loaded, The amount of clear toner loaded will be limited. As a result of the determination, if the process color priority mode is set, the process proceeds to step 907, and if not, the process proceeds to step 909.

In step 907, a process of generating process color loading amount information (hereinafter, referred to as “process color loading amount information generation processing”) is executed using the spooled process color packets. Here, the process color loading amount information is information indicating how much each CMYK toner is loaded on the target pixel of interest in total (total loading amount of each CMYK toner). The process color loading amount information generation process and the above-mentioned special color loading amount information generation process are basically the same except that the target color is different, and the details will be described later.

In step 908, a process of adding the process color loading amount information generated in S907 to the attribute data inside the packet of the special color is executed. Specifically, a process of embedding process color loading amount information in unused bit 4 and bit 5 of the attribute data which is 8-bit data is performed. The details will be described below. First, the total toner amount of all process colors calculated by the process color special color loading amount information generation process is divided into four levels of "0 to 3". Table 3 shows an example of leveling.

In the case of Table 3, as in the case of Table 1, if the total toner loading amount is 0%, it is set to "0", if it is 1% to 60%, it is set to "1", and if it is 61% to 130%, it is set to "". The level is divided into "2" and "3" if it is 131% or more. Since there are four colors of CMYK, the rest excluding 0%, which does not carry toner at all, is divided into three equal parts, and if it is 1% to 133%, it is set to "1", and if it is 134% to 266%, it is set to "2". If it is 267% or more, it is possible to classify it into "3". The reason why such leveling is not performed is in consideration of the precondition that the limit value of the amount of toner that can be stably fixed is about 200% in the case of the present embodiment. That is, when the toner loading amount is 200% or more, it is sufficient to handle all of them in the same manner. When the leveling of the total toner loading amount is completed, the level value obtained by the leveling is converted into a binary number and stored for bit4 and bit5 of the attribute data. Table 4 shows how the process color loading amount information is added to the attribute data.

As described above, bit information representing the total toner loading amount of the process color is added to the empty bits. As a result, the print processing unit 231 in the image processing chip 201 that processes packets of special colors can grasp how much each toner of CMYK is loaded in total per unit area.

_{In step 909, a packet (“S 1} S ₂ + Z ₂ ”) including pixel data of a special color and attribute data is sent to the print processing unit 231. When the process color priority mode is specified, the attribute data in the packet transmitted in this step stores information on the total loading amount of each CMYK toner in the unused bits. On the other hand, the attribute data in the packet transmitted when the process color priority mode is not specified does not include information on the total loading amount of each CMYK toner (the initial value 0 is stored in the unused bit). As it is).

The above is the content of the packet editing process.

≪Special color loading amount information generation processing≫
Subsequently, the special color loading amount information generation process in step 903 described above will be described in detail with reference to the flowchart of FIG.

First, in step 1001, the pixel positions of interest in the two color plate images corresponding to the two types of special colors (S ₁ and S _{2) are determined.}

In the following step 1002, the density value of the pixel of interest in the color plate image of _{S 1 of the first color is converted into the toner loading amount.} A conversion table as shown in FIG. 11 is used for conversion from the concentration value to the toner loading amount. In FIG. 11, the horizontal axis represents the input density value (the maximum value is 255 if the pixel data is 8-bit data), and the vertical axis represents the output toner loading amount. As shown in FIG. 11, the toner loading amount is converted to a maximum of 100% per color.

Then, in step 1003, the density value of the pixel of interest in the color plate image of _{S 2 of the second color is converted into the toner loading amount.} At this time, the same conversion table as the first color may be used, or an individual conversion table may be prepared for each special color and a dedicated conversion table corresponding to each special color may be used.

Next, in step 1004, the toner loading amount of the attention pixel in the color plate image of _{S 1} obtained in step 1002 and the toner loading amount of the attention pixel in the color plate image of _{S 2 obtained in step 1003 are added up.} To do. For example, in a pixel of interest, if S ₁ is gold and the toner loading amount is 80%, and S ₂ is silver and the toner loading amount is 50%, the total toner loading amount in the pixel of interest is 130%. Become. When there are two types of special colors, the maximum value of the toner loading amount is 200%.

In step 1005, it is determined whether or not the calculation of the total toner loading amount of _{S 1} and S ₂ is completed for all the pixels constituting the color plate image to be processed. If there are unprocessed pixels, the process returns to step 1001 to determine the position of the next pixel of interest, and processing continues. On the other hand, if the calculation of the total toner loading amount of _{S 1} and S _{2 is completed for all the pixels, this process is exited.}

The above is the content of the special color loading amount information generation process. In the present embodiment, the case of two kinds of special colors has been described, but when three or more kinds of special colors are used, the processing may be performed in the same manner. That is, the process of converting the above-mentioned density value into the toner loading amount may be performed for the number of colors, and the toner loading amount obtained in each process may be added up.

Further, the concept of the process color loading amount information generation process in step 907 is the same. That is, the process of converting the density value into the toner loading amount for each pixel of interest may be performed for each color plate image of CMYK, and the total toner loading amount of CMYK may be obtained for each pixel of interest.

≪Print image processing (1) ≫
Subsequently, the print image processing executed by the print processing unit 230 in the image processing chip 200 will be described with reference to the flowchart of FIG.

First, in step 1201, a packet (“CMYK + Z ₁ ”) including process color pixel data and attribute data is received from the system control unit 210. This packet is the packet transmitted in step 905 in the packet editing process described above, and is transmitted via the image ring bus switch 220. The received packet is decoded by the image expansion unit 401 and converted into raster image data by the packet raster conversion unit 402.

In the following steps 1202 to 1204, various image processing is executed by the printer image processing unit 403. Specifically, in step 1202, the color space conversion process by the color space conversion unit 406 is performed, in step 1203, the toner loading amount limiting process is performed by the loading amount limiting processing unit 407, and in step 1204, the halftone processing unit 408 performs halftone processing. The processes are executed in order. The order of image processing is not limited to the above. In this case, in the toner loading amount limiting process in step 1203, the special color loading amount information embedded in the attribute data is used. Specifically, in each pixel, the total of the special color toner loading amount and the process color toner loading amount is within the range of the limit value (200% in this case) at which the toner can be appropriately fixed on the paper. The amount of toner on the process color is limited so that it fits inside. The details of the toner loading amount limiting process will be described later.

Then, in step 1205, the print data of the process colors subjected to the above-mentioned various image processing are sequentially sent to the printer unit 140 by the predetermined delay control by the inter-drum delay control unit 409. Then, the printer unit 140 transfers, fixes, and outputs each CMYK toner whose loading amount is appropriately limited based on the received process color print data.

≪Print image processing (2) ≫
Subsequently, the print image processing executed by the print processing unit 231 in the image processing chip 201 will be described with reference to the flowchart of FIG.

First, in step 1301, a packet (“S ₁ S ₂ + Z ₂ ”) including pixel data and attribute data of a special color is received from the system control unit 210. This packet is the packet transmitted in step 909 in the packet editing process described above, and is transmitted via the image ring bus switches 220 and 221 and further via the external ring bus interfaces 280 and 281. The received packet is decoded by the image stretching unit 401 and converted into raster image data by the packet raster conversion unit 402, as in step 1201 described above.

In the following steps 1302 to 1304, the image processing corresponding to each of the above steps 1202 to 1204 is executed by the printer image processing unit 403 for the special color. In this case, in the toner loading amount limiting process in step 1303, the process color loading amount information embedded in the attribute data is used. Specifically, in each pixel, the special color toner loading amount is limited so that the total of the special color toner loading amount and the process color toner loading amount is within the range of the appropriate toner fixing limit value. Toner. The difference between the toner loading amount limiting process in step 1303 of this flow and the toner loading amount limiting process in step 1203 described above is whether the color to be processed is a process color or a special color, which is specific. The processing contents are the same.

Then, in step 1305, the print data of the special color subjected to the above-mentioned various image processing is sequentially sent to the printer unit 140 by the predetermined delay control by the inter-drum delay control unit 409. Then, the printer unit 140 transfers, fixes and outputs each of the toners _{S 1} and S ₂ whose loading amount is appropriately limited based on the received special color print data.

≪Toner loading amount limiting process≫
Next, the toner loading amount limiting process (step 1203) executed by the loading amount limiting unit 407 of the print processing unit 230 in the image processing chip 200 will be described with reference to the flowchart of FIG.

First, in step 1401, the attribute data of the pixel of interest is acquired for the raster image of the process color after the color space conversion process. As described above, the attribute data acquired here includes the special color loading amount information. In the following step 1402, the load limit value N is determined based on the acquired attribute data. The table of FIG. 15 shows an example of the load limit value N determined according to the attribute data. In the case of the present embodiment, the values are entered from bit0 to bit5 in the attribute data bit0 to bit7, and the loading amount limit value N is determined according to the values of the three bits of bit0, bit4, and bit5 in the values. .. bit0 is a part of the bit indicating the object attribute, and when the value of bit0 is "0", it indicates that it is an image or graphic object, and when the value of bit0 is "1", it is a character or line object. Is shown. Here, in order to change the loading amount limit value N depending on whether the pixel of interest is a character or a line and other cases, the value of bit0 is also referred to in addition to bit4 and bit5 of the special color loading amount information. In the example of FIG. 15, the loading amount limit value N is set so that the character portion and the line portion are darker than the other portions. Then, for example, when the value indicating the amount of the special color toner loaded is "0" (bit4 = 0 and bit5 = 0), the color of the packet processed by the other image processing chip (here, the special color) is Will not carry toner regardless of the object attribute. In other words, since it is not necessary to consider the amount to be turned to the special color toner, each CMYK toner loading amount related to the process color packet to be processed is the loading amount limit value equivalent to the limit value of the fixable toner amount (here). Then it becomes "180%" or "200%"). On the other hand, when the value indicating the amount of the special color toner loaded is "3" (bit4 = "1" and bit5 = "1"), a large amount of the special color toner is loaded. In this case, the amount of each toner loaded in CMYK is further limited by the amount that a large amount of special color toner needs to be loaded (here, the loading amount limit value = "0%"). As described above, the larger the value indicating the loading amount of the special color toner, the smaller the loading amount limit value N for the process color is set, and the reduction amount of each toner of CMYK is controlled to be large.

When No is determined in the mode determination process (step 902 and step 906) in the flow of FIG. 9 described above, the load amount information regarding other packets is not embedded in the attribute data. Therefore, when the determination result is No, the values of bit4 and bit5 of the attribute data remain the initial values (that is, "0"), and the loading amount limit value N takes the maximum value. Therefore, in this case, it is possible to load the toner of the color processed by the own chip without worrying about the amount of toner of the color processed by the other image processing chip. The example shown in FIG. 15 is just an example, and the load limit value can be freely controlled by appropriately combining the values of the bits included in the attribute data.

Next, in step 1403, the total sum SUM of the toner loading amount of each CMYK is set based on the density value indicated by the pixel data in the pixel of interest. For example, if the concentration value is (C, M, Y, K) = (128,128,128,0), the total SUM value is "150% (= 50% + 50% + 50% + 0)". In the following step 1404, it is determined whether or not the value of the total SUM set in step 1403 is larger than the loading amount limit value N set in step 1402. If the total SUM value is larger than the loading amount limit value N, the process proceeds to step 1405 in order to adjust the toner loading amount. On the other hand, when the total SUM value is equal to or less than the loading amount limit value N, it is not necessary to adjust the loading amount of each CMYK toner for the pixel of interest, and the loading amount of each toner input to the loading amount limiting unit 407 is not required. Can be output as it is. Therefore, the process proceeds to step 1411 in order to process the next pixel.

Each process from the next step 1405 to step 1407 is a general under color removal (UCR) process. First, in step 1405, the difference is obtained by subtracting the loading limit value N from the value of the total SUM, and dividing it by 2 to obtain a value ((SUM-N) / 2). Then, the minimum value from the obtained "(SUM-N) / 2" value and each toner loading amount of CMY is determined as the UCR value indicating the reduction amount. Next, in step 1406, the value obtained by subtracting the UCR value from each toner loading amount of CMY is used as the toner loading amount of each CMY after the UCR treatment. Then, in step 1407, the value obtained by adding the UCR value determined in step 1405 to the toner loading amount of K is used as the toner loading amount of K after the UCR treatment. At this time, if the value after adding the UCR value exceeds "100%", which is the upper limit value that the toner loading amount of K can take, the upper limit value is set as the toner loading amount of K.

Next, in step 1408, the total sum of the toner loading amounts of the CMYKs after the UCR treatment obtained in steps 1406 and 1407 is obtained, and the obtained values are set as new total SUM values. In the following step 1409, it is determined whether or not the value of the total SUM set in step 1408 is larger than the loading amount limit value N set in step 1402. If the current value of the total sum SUM is larger than the loading amount limit value N, the process proceeds to step 1410 in order to perform the same rate reduction process. On the other hand, when the current value of the total sum SUM is equal to or less than the loading amount limit value N, the same rate reduction processing is unnecessary, so the process proceeds to step 1411 in order to process the next pixel. When the same rate reduction process is not performed, the toner loading amount determined in step 1406 for CMY and the toner loading amount determined in step S1407 for K are output values in the loading amount limiting unit 407.

Next, in step 1410, the same rate reduction process of reducing the amount of toner loaded in each CMY color at the same rate is executed. Specifically, the value (NK) obtained by subtracting the toner loading amount of K from the loading amount limit value N set in step 1402 is proportionally divided according to the ratio of each toner loading amount of CMY. Then, each toner loading amount of CMY obtained by performing such apportionment becomes an output value in the loading amount limiting unit 407. As for the toner loading amount of K, the toner loading amount after the UCR treatment determined in step 1407 is used as the output value as it is.

Then, in step 1411, it is determined whether or not the above processing is completed for all the pixels. If there are unprocessed pixels, the process returns to step 1401 to determine the next pixel of interest, and processing continues. On the other hand, if the processing is completed for all the pixels, this processing is exited.

The above is the content of the toner loading amount limiting process (step 1203) executed by the loading amount limiting unit 407 of the print processing unit 230 in the image processing chip 200.

Then, the same process as the flow of FIG. 14 _{is executed on the special color (S 1} , S ₂ ) side, that is, the load limit process 407 of the print process section 231 in the image processing chip 201 (load limit process). It can also be applied to step 1303). In this case, in the flowchart of FIG. 14, C representing cyan is _{replaced with the special color S 1} , M representing magenta is _{replaced with the special color S 2} , and Y representing yellow and K representing black have their respective toner loading amounts. It may be replaced with "0%". The flowchart of FIG. 16 is a visualization of the above replacement, and the flow and algorithm of FIG. 14 are common. Hereinafter, a brief description will be given.

First, the attribute data of the pixel of interest is acquired for the raster image of the special color after the color space conversion process (step 1601). As described above, the attribute data acquired here includes the process color loading amount information. Then, the load limit value N is determined based on the acquired attribute data (step 1602). At this time, the larger the value indicating each toner loading amount of the process color specified by bit4 and bit5 of the attribute data, the smaller the value of the loading amount limit value N in the special color (the reduction amount of the special color toner is large). Become.). Further, the total sum SUM of the toner loading amounts of _{S 1} and S ₂ is set based on the density value indicated by the pixel data of the pixel of interest (step 1603). Then, if the set total sum SUM value is larger than the loading amount limit value N set in step 1602 (Yes in step 1604), the process proceeds to step 1605 to adjust the toner loading amount. Now, since Y = "0" at all times, the UCR value obtained in step 1605 is always "0". Therefore, the base removal process is not carried out. As a result, the toner loading amounts (“S _{1 −} UCR” and “S _{2 − UCR”) of the special colors S 1} and S ₂ obtained in step 1606 are the toner loading amounts input to the loading amount limiting unit 407. Will remain. Further, in the same rate reduction process (step 1610) executed when the total SUM value exceeds the load limit value N (Yes in step 1609), the toner load is reduced at the same rate for _{S 1} and S _2. Is done. As a result, the total toner loading amount for the special color is controlled so as not to exceed the loading amount limit value N set in step 1602.

The above is the content of the toner loading amount limiting process (step 1303) executed by the loading amount limiting unit 407 of the print processing unit 231 in the image processing chip 201. In this way, since the same image processing algorithm is used only by replacing variables, the image processing chips 200/201 can be shared.

According to the present embodiment, by embedding information on the amount of toner of the color processed by the other image processing chip in the attribute data, the amount of the other image processing chip loaded without providing a new interface on the image processing chip. Information can be referred from attribute data. This makes it possible to control the total toner amount so that it does not exceed the specified value even in a configuration in which a plurality of image processing chips are used to print a number of colors exceeding four colors.

(Other embodiments)
The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It is also possible to realize the processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

100 MFP
120 Main controller 200, 201 Image processing chip 202 Ring bus 210 System control unit 407 Load limit processing unit

Claims (12)

An image processing controller for forming an image by an electrophotographic method using image data having more than four colors.
A first image processing chip that processes image data having a predetermined number of colors among the image data having a number of colors exceeding four colors, and
A second image processing chip that processes image data of the remaining number of colors excluding the image data of the predetermined number of colors among the image data of the number of colors exceeding the four colors, and
The first loading amount information indicating the toner loading amount used for image formation of the image data of the remaining number of colors processed by the second image processing chip, and the processing by the first image processing chip. A generation means for generating a second load amount information indicating a toner load amount to be used for image formation of the image data having a predetermined number of colors.
The first loading amount information is added to the image data of the predetermined number of colors processed by the first image processing chip, and the remaining number of colors processed by the second image processing chip is added. An addition means for adding the second loading amount information to the image data, and
With
The first image processing chip performs the first loading amount limiting processing on the toner of the predetermined color number based on the first loading amount information added to the image data of the predetermined color number.
The second image processing chip performs a second loading amount limiting process on the toner of the remaining color number based on the second loading amount information added to the image data of the remaining color number.
An image processing controller characterized by that. The generation means
The first loading amount information is generated by converting the density values in each image data of the remaining number of colors into the toner loading amount and adding them together.
The second loading amount information is generated by converting the density values in each image data of the predetermined number of colors into the toner loading amount and adding them together.
The image processing controller according to claim 1. The image data is composed of pixel data indicating a density value in pixel units and attribute data indicating attributes in pixel units.
The additional means converts the total toner loading amount obtained by the totaling into a value corresponding to a predetermined number of bits, and the converted value is used as the first or second loading amount information in the attribute data. The image processing controller according to claim 2, wherein the image processing controller is embedded. The image data having a predetermined number of colors is image data corresponding to the four colors of CMYK.
The image data of the remaining number of colors is image data corresponding to at least one special color.
The image processing controller according to claim 1. The first image processing chip performs background removal processing on the image data corresponding to the CMYK, and performs each color equality reduction processing on the image data after the background removal processing, thereby mounting the first image. Achieves quantity limit processing,
The second image processing chip realizes the second loading amount limiting process by performing the same color ratio reduction process for each color on the image data corresponding to the special color.
The image processing controller according to claim 4. In the mode setting related to the above-mentioned amount limiting process, when the mode that does not limit the loading amount is set for the special color,
The generation means generates the first loading amount information,
The addition means adds the first loading amount information to the image data corresponding to the CMYK processed by the first image processing chip.
In the first image processing chip, the larger the value indicating the total toner loading amount of the special color indicated by the first loading amount information, the larger the reduction amount of the toner loading amount for the CMYK. The first loading amount limiting process is performed.
The image processing controller according to claim 5. In the mode setting related to the above-mentioned amount limiting process, when the mode in which the loading amount is not limited is set for the CMYK,
The generation means generates the second load information,
The adding means adds the second loading amount information to the image data corresponding to the special color processed by the second image processing chip.
In the second image processing chip, the larger the value indicating the total toner loading amount of the CMYK indicated by the second loading amount information, the larger the reduction amount of the toner loading amount for the special color. The second loading amount limiting process is performed.
The image processing controller according to claim 5. The image processing controller according to any one of claims 1 to 7, wherein the first image processing chip and the second image processing chip have the same configuration. The image processing controller according to any one of claims 1 to 8, wherein the first image processing chip and the second image processing chip are image processing chips capable of supporting up to four colors. .. The image processing controller according to any one of claims 1 to 9.
An image forming means for forming an image on a recording medium using image data having a number of colors exceeding the four colors processed by the image processing controller.
An image forming apparatus characterized by being provided with. It is a control method of an image processing controller for forming an image by an electrophotographic method using image data having a number of colors exceeding four colors.
The image processing controller
A first image processing chip that processes image data having a predetermined number of colors among the image data having a number of colors exceeding four colors, and
A second image processing chip that processes image data of the remaining number of colors excluding the image data of the predetermined number of colors among the image data of the number of colors exceeding the four colors, and
With
The first loading amount information indicating the toner loading amount used for image formation of the image data of the remaining number of colors processed by the second image processing chip, and the processing by the first image processing chip. A generation step of generating a second load amount information indicating a toner load amount to be used for image formation of the image data having a predetermined number of colors.
The first loading amount information is added to the image data of the predetermined number of colors processed by the first image processing chip, and the remaining number of colors processed by the second image processing chip is added. An addition step of adding the second loading amount information to the image data, and
Including
Based on the first loading amount information added to the image data of the predetermined color number, the first image processing chip is made to execute the first loading amount limiting process for the toner of the predetermined color number.
The second image processing chip is made to execute a second loading amount limiting process for the toner of the remaining color number based on the second loading amount information added to the image data of the remaining color number.
A control method characterized by that. A program for causing a computer to function as an image processing controller according to any one of claims 1 to 9.

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