JP4857149B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that compresses image data composed of a plurality of bands in units of bands or in units of a plurality of bands and temporarily stores the data and expands and outputs the data during printing.

  2. Description of the Related Art Conventionally, there is known an image forming apparatus that compresses image data composed of a plurality of bands in units of bands or in units of a plurality of bands and temporarily stores the data and expands and outputs the data during printing.

However, such an image forming apparatus cannot confirm whether or not valid image data is included in an image to be compressed in units of one band or in arbitrary plural bands.
JP 2001-113759 A JP 2003-094735 A

  The present invention has been made in view of such problems, and provides an image forming apparatus capable of confirming whether or not valid image data is included in an image to be compressed in units of one band or in units of arbitrary plural bands. With the goal.

In order to achieve the above object, as a first aspect, the present invention performs compression for completing one band of image data in an image for each band, and for a descriptor in which a code-side compressed data completion code is written. An image forming apparatus including a compressor for writing a white image detection result at the time of compression and a write DMA controller having a function for writing a write-back flag to a descriptor is provided. Then, it is preferable to associate the image-side band with the code-side band corresponding to the write-back flag, and an expander that directly outputs the image data corresponding to the descriptor in units of bands by setting the descriptor is provided. Is preferred. Thereby, it can be confirmed whether or not valid image data is included for each image band. This also makes it easy to associate an image with a code. Further, this enables expansion even if the data corresponding to the image-side descriptor is replaced with data corresponding to the code-side descriptor.

In order to achieve the above object, according to a second aspect of the present invention, compression processing for image data of a plurality of bands in an image is completed according to an instruction from an image-side descriptor, and a code-side compressed data completion code is written. The present invention provides an image forming apparatus including a compressor for writing a white image detection result at the time of compression and a write DMA controller having a function for writing a write back flag to the descriptor. Then, it is preferable to associate the image-side band with the code-side band corresponding to the write-back flag, and an expander that directly outputs the image data corresponding to the descriptor in units of bands by setting the descriptor is provided. Is preferred. Thereby, it is possible to confirm whether or not valid image data is included for each of a plurality of arbitrary bands, not for each image. This also makes it easy to associate an image with a code. Further, this enables expansion even if the data corresponding to the image-side descriptor is replaced with data corresponding to the code-side descriptor.

In the first or second aspect of the present invention, it is more preferable to include a read DMA controller having a fill pattern function for outputting a predetermined pattern without memory access by setting a descriptor. As a result, data can be output by operating the decompressor without memory access. Further, it is preferable to determine whether there is color data based on the white image detection result information of a plurality of bands, and to determine whether to perform monochrome printing or color printing. It is more preferable to store only the code data of the black image and discard the image data of other colors. As a result, the compressor can be operated normally, and unnecessary memory can be released. That is, by destroying the color code data that does not need to be retained, Ru can speed up the processing speed by effectively utilizing the memory.

In any of the above configurations of the first or second aspect of the present invention , the white image is detected by rewriting the code side descriptor based on the white image detection result of the code side descriptor written by the compressor. It is preferable to replace the written descriptor with a descriptor indicating a fill pattern. As a result, when this band is developed, reading of the data area does not occur, so that the congestion of the data bus is eliminated, the other resources can be occupied by the data bus, and the image processing can be speeded up. In addition to this, it is more preferable to release the memory occupied by the descriptor before replacement and the compressed data indicated by the descriptor after the image data is compressed. As a result, unnecessary code data and descriptors can be deleted, so that the amount of memory used can be saved, and the speed can be increased by passing memory resources to other resources. Alternatively, it is more preferable to release the memory occupied by the descriptor before replacement and the compressed data pointed to by the descriptor during the compression of the image data. It is more preferable to write the compressed data from the next band on to the compressed data area occupied by. As a result, the data size temporarily secured at the time of compression can be reduced, the memory usage can be saved, and the speed can be increased by passing the memory resource to other resources. Further, the compressed data corresponding to the image one band during compression can be replaced with another data, Ru Hakare relevance matching descriptor.

  According to the present invention, it is possible to provide an image forming apparatus capable of confirming whether or not effective image data is included in an image to be compressed in units of one band or in units of arbitrary plural bands.

  A preferred embodiment of the present invention will be described. FIG. 1 shows a configuration of an image forming unit of the image forming apparatus according to the present embodiment. The image processing unit 100 includes a CPU 101, a memory 102, a first read DMAC (Direct Memory Access Controller) 103, a compressor 104, a write DMAC 105, a second read DMAC 106, a video decompressor 107, and a plotter 108. The write DMAC 105, the second read DMAC 106, the video decompressor 107, and the plotter 108 are provided with four colors C to K corresponding to the respective colors of CYMK.

  The CPU 101 makes settings for each module. The memory 102 records a descriptor for DMAC control, an image before compression, and a code after compression. The first lead DMAC 103 is connected to the compressor 104. The compressor 104 includes a white image detection module 1041 that determines whether or not all input data from the first read DMAC 103 is a white image. The write DMAC 105 includes a write-back generation module 1051 that writes a white image detection result to a descriptor of a hand that writes a compression termination code output from the compressor. The second read DMAC 106 includes a pattern generation module 1061 that generates a specified pattern without inputting data in accordance with descriptor information. The video decompressor 107 decompresses the code data, and sends the decompressed image 108 to the plotter. The plotter 108 forms an image input from the video decompressor.

Here, it is assumed that the descriptor has the information of the data structure shown in FIG. 2 on the memory 102, and the descriptor and the corresponding data constitute one band. Furthermore, a descriptor and band chain are configured by designating another descriptor address in the “next descriptor (NDP)”. The write back flag, white image detection result, and pattern fill flag are set to 0 at the start of compression. The write back flag is set in the descriptor that is the end of the image (set to 1). The white image detection result is set when a white image (image data having all gradation values of 0) is detected. The pattern fill flag is set when compressed data is not read from the memory 102.
In addition, information indicating that the data is an image is written in the image type of the image-side descriptor, and information indicating that the data is a code is written in the image type of the code-side descriptor.

  The color image handled here is composed of C, M, Y, and K planes, and each plane image is divided into units called bands. Here, it is assumed that the image of each plane is divided into n bands.

  As shown in FIG. 3, at the time of compression, the descriptor is configured to be compressed in order of the first band of the C plane, the first band of the M plane,..., The n band of the K plane. .

4 to 7 show the flow of processing during image compression.
In the descriptor of each band on the image side, a code end instruction flag is set for each arbitrary processing unit (for example, for each single color image) (step S101). When this flag is set, the compressor completes and compresses the code data every time one band of image data ends. In that case, the terminal code is finally written in the code data. In the descriptor corresponding to the band of the code data in which the terminal code is written, if 1 is written in the write-back flag and the compressed band image data is a white image (a state in which nothing is written), 1 is written in the white image detection result of the descriptor on the code side, otherwise 0 is written (steps S102 to S109).

Here, when the configuration is such that the operation is temporarily stopped when the compressor finishes reading the image data for one band (step S110), the write-back of the descriptor corresponding to the code-side data that has just been written. When the flag and the white image detection flag are both 1 (step S111 / Yes), it is considered that the image that is the source of the compressed image data is a white image, and the compressed data and descriptor corresponding to this band are Replacement with a descriptor using a fill pattern flag, which is equivalent data (steps S112 and S113).
In addition, the memory area is released, the descriptor on the code side is rewritten, and the memory address (the memory that the previous descriptor was supposed to use) was released immediately before the start address (SA) for the descriptor that has not been written yet. It is determined whether or not the address is designated.

  As another implementation, when the operation of the compressor 104 ends when the image data for one image (for a plurality of bands) is written by the compressor 104 (step S110 / No, S115 / Yes), After the operation is completed, the program reads the descriptors on the code side in the order of writing (step S116). If the write-back flag is set and the descriptor for which the white image detection flag is set exists (step S116). (S117 / Yes), the code data and the descriptor are deleted (step S118). The data to be deleted and the descriptor are bands in which data obtained by compressing a white image detected image is written. That is, from the band next to the band in which the write back is performed immediately before the band in which the white image detection flag is set to the band in which the white image detection flag is set. Note that the band on which the write back is performed can be determined based on the write back flag.

  Furthermore, a descriptor is generated that is used instead of a code obtained by compressing the white image detected image. This descriptor has a data length equivalent to a white image detected image, sets a pattern fill flag, outputs the data set in the fill pattern data without read access, and is set as an image in the image type. It shall be. After the descriptor is created, the descriptor information immediately before the deleted descriptor is changed, the next descriptor address is changed so as to point to the created descriptor, and the descriptors are connected (step S119).

  If the band descriptors corresponding to the images of the C, M, and Y planes are scanned after compression and all the bands that have been written back are detected (step S121 / Yes), the printing process , C, M, and Y planes are not printed (step S122). In this case, the code data of the C, M, and Y planes are deleted from the memory 102 at this time.

  When the above operation is completed, the compressed data is configured as a code of the first band of the C plane, M1, Y1, K1, C2, M2,..., Kn, as shown in FIG. This structure is rearranged and replaced with an independent descriptor structure for each plane. The rearrangement is performed by rewriting the next descriptor address of each descriptor.

Next, the operation of the video decompressor 107 in the decompression process (printing process) will be described.
9 and 10 show the flow of processing during decompression.
In order to decompress the code data for each of the C, M, Y, and K planes, the CPU 101 sets and activates each video decompressor 107 (steps S201 to S203). The second read DMAC 106 connected to the video decompressor 107 sequentially reads the code descriptor (step S204). Normally, based on the start address specified in the descriptor, data is read from the memory 102 by the size of the data length, and the data is sent to the video decompressor 107.

  If the pattern fill flag of the descriptor is set (step S205 / Yes), the second read DMAC 106 does not read the data on the memory 102, and fills the pattern data with the pattern data for the data length. (Step S206).

The video decompressor 107 normally decompresses the data transferred from the second read DMAC 106 in order and transfers it to the plotter 108 (step S211). In this case, the image type of the descriptor corresponding to the transferred data is set to “code” (step S207 / No). However, when the image type information is “image” (step S207 / Yes), the decompressor 107 regards the data sent from the read DMAC 106 as an image without considering it as a code, and sends the sent data. The data is directly transferred to the plotter 108 (step S208).
The above processing is repeated until the end of the last descriptor (step S209).

  As described above, the image forming apparatus according to the present embodiment can confirm whether or not valid image data is included in an image to be compressed in units of one band or any plurality of bands.

  The above embodiment is an example of a preferred embodiment of the present invention, and the present invention is not limited to this and can be variously modified.

1 is a diagram illustrating a configuration of an image forming apparatus according to a preferred embodiment of the present invention. It is a figure which shows the structural example of a descriptor. It is a figure which shows the descriptor before and behind compression. 4 is a flowchart illustrating a processing flow when an image is compressed in the image forming apparatus. 4 is a flowchart illustrating a processing flow when an image is compressed in the image forming apparatus. 4 is a flowchart illustrating a processing flow when an image is compressed in the image forming apparatus. 4 is a flowchart illustrating a processing flow when an image is compressed in the image forming apparatus. It is a figure which shows the state which replaced the code data by the descriptor structure independent for every plane. 6 is a flowchart showing a flow of processing at the time of code expansion of the image forming apparatus. 6 is a flowchart showing a flow of processing at the time of code expansion of the image forming apparatus.

Explanation of symbols

100 Image forming apparatus 101 CPU
102 Memory 103 First read DMAC
104 Compressor 105 Write DMAC
106 DMAC for second read
107 Video Extender 108 Plotter 1041 White Detection Module 1051 Write Back Generation Module 1061 Pattern Generation Module

Claims (9)

Compresses one band of image data in the image to complete each band, writes a white image detection result at the time of compression to the descriptor in which the compression data completion code on the code side is written, and writes to the descriptor A write DMA controller having a function of writing a back flag, the image back band is associated with a code side band corresponding to the write back flag, and the descriptor is set to correspond to the descriptor in a band unit. An image forming apparatus comprising a decompressor that outputs the processed image data as it is . A compressor that completes compression processing for image data of a plurality of bands in an image by an instruction of an image side descriptor, and writes a white image detection result at the time of compression to a descriptor in which a compression data completion code on the code side is written; A write DMA controller having a function of writing a write-back flag to the descriptor. The write-back flag associates a band on the image side with a corresponding code-side band. An image forming apparatus comprising an expander that outputs image data corresponding to the descriptor as it is . 3. The image forming apparatus according to claim 1, further comprising a read DMA controller having a fill pattern function for outputting a predetermined pattern without memory access by setting the descriptor . 4. The method according to claim 1, wherein whether or not there is color data is determined based on the white image detection result information of a plurality of bands, and it is determined whether to perform monochrome printing or color printing. 2. An image forming apparatus according to item 1 . 5. The image forming apparatus according to claim 4 , wherein when it is determined that black and white printing is to be performed, only the code data of the black image is retained and the image data of other colors is discarded . Based on the white image detection result of the code side descriptor written by the compressor is performed, rewriting the code side descriptors, characterized Rukoto replacing descriptor white image is detected in the descriptor of the fill pattern instruction claims Item 6. The image forming apparatus according to any one of Items 1 to 5. 7. The image forming apparatus according to claim 6, wherein the memory occupied by the descriptor before replacement and the compressed data indicated by the descriptor is released after the image data is compressed . 7. The image forming apparatus according to claim 6, wherein the memory occupied by the descriptor before replacement and the compressed data indicated by the descriptor is released during the compression of the image data . 9. The image forming apparatus according to claim 8 , wherein the write-side descriptor is rewritten during the compression, and the compressed data of the next band or later is written in the compressed data area occupied by the white image .

Images