JP4725799B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that processes and prints a scanned image, for example, and particularly relates to a technique that supports A3 size without increasing the size of an image processing circuit.

  In image processing of scan data by a copying machine or the like, there is generally a method of processing at the same speed as the input speed using a line memory. In this method, modules in the image processing circuit that perform processing such as input correction, resolution conversion, filter, and screen perform processing while referring to scan data for several lines stored in the line memory provided in each module. . Although such a processing method is high-speed, it is necessary to have a line memory for the necessary modules as described above, and there is a problem that the image processing circuit becomes large. On the other hand, for example, Patent Document 1 proposes a method in which one page is temporarily stored in an image memory and processed while reading out image data therefrom. This method has an advantage that the image processing circuit can be miniaturized because it is not necessary to have a line memory.

JP2004-220584 (abstract)

  However, the technique described in Patent Document 1 has a problem that the scan data is read and processed one by one from the image memory, so that the processing becomes slow and the size of the image memory increases. In the copying machine, the low-speed machine is mainly the A4 size limited type, but the high-speed machine is mostly compatible with the A3 size. On the other hand, since image processing requires high-speed processing using a line memory, it is generally integrated and mounted on an image processing LSI such as an ASIC. For this reason, when designing an image processing LSI for a high-speed machine, it is necessary to mount a line memory corresponding to A3 size. When such an image processing LSI is applied to an A4 size apparatus, overspec and As a result, there was a problem that the manufacturing cost was high.

  Accordingly, an object of the present invention is to provide an image forming apparatus capable of supporting A3 size while having a line memory corresponding to A4 size and capable of high-speed processing.

An image processing apparatus according to the present invention includes : an image processing circuit that processes first image data; and an image memory that stores image data processed by the image processing circuit and outputs the image data to an image output unit. circuit includes a plurality of modules for processing the first image data inputted, is connected to each module and a compatible line memory to the size of the first image data, the plurality of modules has been entered The first image data is stored in the line memory to perform a predetermined process, and when second image data exceeding the size of the line memory is input, image data corresponding to the size exceeding the size is stored. stored in the picture image memory as an image memory used area, in the second handle of the image data in the plurality of modules, the second image data, Divided into data stored in the line memory and data stored in the image memory, and the plurality of modules include a first module and a second module, and the first module includes the first module and the second module. The divided area of the second image data allocated to the image memory does not overlap the divided area of the second image data allocated to the image memory in the second module. It is said.

  In the image forming apparatus having the above configuration, when the second image data exceeding the size of the line memory is input, the image data corresponding to the size exceeding the size is stored in the image memory as an image memory use area. Can be processed by referring to the entire second image data by the line memory and the image memory. Therefore, for example, even when an A4 size compatible image processing LSI is mounted, A3 size image formation can be performed, which is economical. Further, since only the image data exceeding the size is stored in the image memory, it is not necessary to increase the capacity of the image memory, and the access time to the image memory can be shortened.

  In the present invention, the module refers to the line memory use area and the image memory use area stored in the line memory in the second image data, and processes the second image data. In the second image data, pixels at substantially the same position in one line are processed by the respective modules. For this reason, if all modules try to transfer the image memory use area of the second image data to the image memory at the same time, the transfer band may not be secured. Therefore, in setting the line memory use area and the image memory use area in the second image data, it is preferable to do the following.

  That is, the second image data is divided by a predetermined number of modules along the line so that the positions of the image memory use areas in each module do not overlap each other. By doing so, the access to the image memory from each module does not overlap, thereby ensuring the transfer bandwidth of the image memory and supporting high speed.

  As another method, the second image data can be divided by the number of colors along the line so that the positions of the image memory use areas in the respective colors do not overlap each other. In color copying, the module processes input image data for each color simultaneously. For example, scan data input from a scanner is converted into R, G, and B data by an input correction module, and the subsequent processing is performed for each color. Therefore, the second image data is divided into three along the line, and for example, an image memory use area is set such that R is the head, G is the rear end, and B is the center. Thus, all modules access the image memory at the first stage of the R process, access the image memory at the middle of the B process, and access the image memory at the end of the G process.

  The division of the second image data can be performed by any method other than the method described above. For example, when performing monochrome copying, modules that are not used appear, so the number of divisions can be changed.

  In the present invention, the size of the line memory does not need to conform to a standard such as A4, and can be arbitrarily set. If the transfer bandwidth and transfer speed for accessing the image memory can be ensured, for example, the size of the line memory can be set to half the size of A4, and the missing amount can be arbitrarily set by compensating with the image memory. Further, the present invention can obtain the same effect when applied not only to a copying machine but also to a printer or a facsimile machine.

  According to the present invention, when the second image data exceeding the size of the line memory is input, the image data corresponding to the size exceeding the size is stored in the image memory as the image memory use area. Processing can be performed while referring to the entire second image data by the memory and the image memory. Therefore, it is economical that a large size image can be formed by mounting an image processing LSI corresponding to a small size. In addition, since only the image data exceeding the size is stored in the image memory, there is no need to increase the capacity of the image memory, and the access time to the image memory can be shortened. It is done.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a control block diagram of a printer according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a control unit that controls the entire printer, and 2 denotes an ASIC for image formation. ASIC is an abbreviation for Application Integrated Circuit, and is an integrated circuit designed and manufactured for a specific application. Scan data is input from the image input unit 3 to the ASIC 2. The ASIC 2 is connected to an image memory 4 serving as a buffer for temporarily storing the formed image data. The stored image data is output to the image output unit 5 and printed by an engine (not shown).

  The ASIC 2 is shown in detail in the middle of FIG. The ASIC 2 includes modules of an input correction unit 20, a color space conversion unit 21, a resolution conversion unit 22, a filter 23, a color space conversion unit 24, and a screen processing unit 25 in order from the left. Among these modules, an A4 size line memory 26 is provided in addition to the color space conversion units 21 and 24. The input correction unit 20 receives scan data from the scanner, and the input correction unit 20 converts the scan data into R, G, and B. The color space conversion unit 21 converts R, G, and B into L, a, and b, and converts them into intermediate colors. The resolution conversion module 22 enlarges / reduces the image. The filter 23 removes noise, smoothes colors, and raises the edges of characters. The color space conversion unit 24 converts R, G, and B images into Y, M, C, and K. The screen processing unit 25 performs image correction.

  The lower part of FIG. 1 shows the configuration of each module having the line memory 26. Each module includes a control unit 30, and the control unit 30 includes a line memory 26 and a DMAC (Dynamic Memory Access Controller) 31. The line memory 26 is for A4, and the cost is reduced. The DMAC 31 transfers the image data to the image memory 4 and reads the transferred image data. The control unit 30 includes an image processing circuit 32 and performs predetermined processing on the image data transferred from the upstream side.

  The image data input from the image input unit 3 is input-corrected in the ASIC 2 → color space conversion → resolution conversion → filter → color space conversion → screen image processing in real time, and then stored in the image memory 4 for image output. The data is output to the unit 5 and printed. In this case, the image data is stored in the line memory 26, and each module performs processing while referring to the stored image data.

  Here, processing of A3 size image data will be described with reference to FIG. As shown in FIG. 2, the A4 size is 5000 pixels per line, whereas the A3 size is 7500 pixels. In this embodiment, since the A4 line memory is used, the A3 size image data cannot be processed only by the line memory 26. Therefore, in the present embodiment, the amount that cannot fit in the line memory 26 is stored in the image memory 4.

  As shown in FIG. 2, the input correction unit 20 stores the first 1/3 (2500 pixels) of the A3 image data in the image memory 4 and the remaining (5000 pixels) in the line memory 26. In the resolution conversion unit 22, the rear 1/3 is stored in the image memory 4 and the rest is stored in the line memory 26. In the filter 23 and the screen processing unit 25, the central ３ is stored in the image memory 4 and the rest is stored in the line memory 26. As a result of such allocation, the module using the image memory 4 changes from the input correction unit 20 to the resolution conversion unit 22 to the filter 23 and the screen processing unit 25. Accordingly, accesses from the modules to the image memory 4 do not overlap, and this makes it possible to secure the transfer bandwidth of the image memory 4 and cope with higher speed.

  FIG. 3 shows an example in which the image data A3 is divided by color. In the input correction unit 20, the image data is converted into R, G, B image data, the first 1/3 of the R image data is stored in the image memory 4, and the rest is stored in the line memory 26. Further, the last 1/3 of the B image data is stored in the image memory 4, and the rest is stored in the line memory 26. Further, the central 1/3 of the G image data is stored in the image memory 4, and the rest is stored in the line memory 26. By such allocation, the color using the image memory 4 changes from R → B → G. Since the color space conversion unit 21 converts R, G, and B into L, a, and b, the image data of A3 may be similarly divided with these colors.

FIG. 3 is a control block diagram of the image forming apparatus according to the embodiment of the present invention. It is a figure which shows an example of the use condition of a memory. It is a figure which shows the other example of the use condition of a memory.

Explanation of symbols

2 ASIC
4 Image memory 20 Input correction unit 21 Color space conversion unit 22 Resolution conversion unit 23 Filter 24 Color space conversion unit 25 Screen processing unit 26 Line memory 30 Control unit 31 DMAC
32 is a diagram processing circuit

Claims (4)

An image processing circuit for processing the first image data;
An image memory that stores image data processed by the image processing circuit and outputs the image data to an image output unit;
The image processing circuit includes a plurality of modules for processing input first image data, and a line memory connected to each module and adapted to the size of the first image data,
The plurality of modules store the input first image data in the line memory to perform a predetermined process, and when the second image data exceeding the size of the line memory is input, stored in the picture image memory minute image data exceeding the size as the image memory use area,
In handling the second image data in the plurality of modules, the second image data is divided into data stored in the line memory and data stored in the image memory,
The plurality of modules includes a first module and a second module;
The divided area of the second image data allocated to the image memory in the first module, and the divided area of the second image data allocated to the image memory in the second module And an image forming apparatus characterized by not overlapping .   The module performs processing of the second image data with reference to a line memory use area stored in the line memory and the image memory use area of the second image data. Item 2. The image forming apparatus according to Item 1.   3. The image forming apparatus according to claim 1, wherein the second image data is obtained by processing pixels at substantially the same position in one line in each of the modules. 4. The module simultaneously processes the input image data for each color,
In setting the image memory use area from the second image data, the second image data is divided along the line by the number of colors, and the positions of the image memory use areas in the respective colors do not overlap each other. The image forming apparatus according to claim 3.

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