JP2002108801A - Information processor, image reader, image forming apparatus, method for storing image data and method for dma transfer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the DMA transfer of image data of a single sheet image in spite of dividing the image data of the single sheet image into plural blocks and converting the image data into forms different for each block. SOLUTION: When a code data quantity after compression is smaller than an original image data quantity (N at a step S2) as the result of dividing the single sheet of image data into the plural blocks, the image data is compressed and stored in an image memory (a step S3). When the code data quantity after compression is larger (Y at a step S2), the image data is stored in the image memory as it is without compressing (a step S4). As for a block consisting of white data including only white or black data including only black (Y at a step S5), the image data in the block stored in the image memory is cleared (a step S6). Then, based on the result of processing at the steps S2 to S5, a system control part prepares the plural descriptors of for each block (a step S8).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information processing apparatus for performing DMA transfer of image data based on a descriptor, an image reading apparatus, an image forming apparatus, a DMA transfer method, and an image for creating a descriptor in that case. It relates to a data storage method.

[0002]

2. Description of the Related Art In recent years, digitalization of copiers has progressed, and various techniques for processing and editing using an image memory have been proposed. As one of such techniques, there is a function called an electronic sort in which a specified number of copies are collectively output by storing image data of a plurality of documents in an image memory, thereby eliminating a sorting operation.

In this case, if the image data is stored in the semiconductor memory as it is in order to hold a plurality of image data, a memory corresponding to the data amount of the stored number is required, and the memory cost is reduced. The following two means are generally used for the reason that the number becomes large.

[0004] A semiconductor memory and a storage memory are used in combination, and a storage device such as a hard disk which is lower in cost than the semiconductor memory is used as the storage memory.

[0005] A semiconductor memory is used as a storage memory, and image data is compressed using a compression process to reduce the amount of data per image, thereby reducing the total memory amount.

[0006] Regarding the chain type DMA technology,
For example, it is disclosed in JP-A-6-103225.

[0007]

When electronic sorting is realized by the above-described means, the specifications such as the number of stored images are affected by the performance of the compression processing. There are various algorithms for compression processing, each with its own strengths and weaknesses, but generally speaking, the compression rate varies considerably depending on the type of image data to be compressed. May exceed 1, that is, the data amount may increase due to compression. For the above reasons, image data is compressed, and data in which the amount of code data after the compression is larger than the original amount of image data is compressed and stored in the form of the code data after the compression. Instead, it is desirable to store the original image data as it is.

An object of the present invention is to divide image data of one image into a plurality of blocks and convert the image data into a different format for each block. That is, DMA transfer is enabled by a command.

[0009] An object of the present invention is to enable the first image data to be stored as compressed image data for blocks whose data amount is increased by compression instead of the original image data. The purpose is to save the storage capacity of the means and reduce the manufacturing costs.

[0010] An object of the present invention is to omit the storage of image blocks such as pure white and pure black,
It is to save the storage capacity of the first storage means and reduce the manufacturing cost.

An object of the present invention is to provide a single color of white or black.
An object of the present invention is to make it possible to reproduce a color of a block made up of a specific one-color image even without storing the image data.

[0012]

According to a first aspect of the present invention, there is provided a judging means for judging a characteristic of image data for each block obtained by dividing image data of one image into a plurality of blocks, and a method for judging the characteristic of the image data. Conversion means for selectively converting the image data of each block into a format, first storage means for storing the converted image data of each block in accordance with the conversion, and DMA from storage means
Descriptor creation means for creating a descriptor to be used for transfer, for each block, including data used for a process of returning each converted block to the image data before conversion for performing the DMA transfer, Second storage means for storing a descriptor, and converting each block back to the image data before conversion based on data used for the processing included in the descriptor, and converting the image data including the plurality of blocks into image data. DM
An information processing apparatus comprising: a DMA controller that performs A transfer based on the descriptor; and performs processing using the image data.

[0013] Therefore, each block can be returned to the image data before conversion by the descriptor and DMA transfer can be performed. Therefore, the image data of one image is divided into a plurality of blocks, and the image data is divided into different formats for each block. Even if the data is converted, the image data of one image can be DMA-transferred by one command.

The characteristics of the image data include, for example, that when compressed, the data amount is larger than that of the original image data, or that the image is an image of only white or black. Converting image data to a format according to characteristics includes, for example, image data compression.

According to a second aspect of the present invention, in the information processing apparatus according to the first aspect, the descriptor includes data indicating whether or not the block is compressed as data used in the processing. .

Therefore, it is possible to store the original image data for blocks whose data amount increases instead of compressing them, and to store them in the first storage means as compressed code data for blocks that do not.
The storage capacity of the first storage means can be saved, and the manufacturing cost can be reduced.

According to a third aspect of the present invention, there is provided the first or second aspect.
In the information processing apparatus described in (1), the descriptor includes data indicating whether or not data transfer from the first storage unit has been executed, as data used for the processing.

Therefore, it is possible to prevent the data transfer from being performed from the first storage means for the block of the image such as one color of white or one color of black, so that the image data of the block is stored in the first storage means. By omitting this step, the storage capacity of the first storage unit can be saved, and the manufacturing cost can be reduced.

According to a fourth aspect of the present invention, in the information processing apparatus according to the third aspect, when the descriptor includes data indicating that the access is not executed, the descriptor is used as the data used for the processing. The data includes data indicating that the block is a specific one-color image.

Therefore, for a block composed of an image of a specific one color such as one color of white or one color of black, the color can be reproduced even if the image data is not stored in the first storage means.

According to a fifth aspect of the present invention, there is provided the information according to any one of the first to fourth aspects, further comprising a photoelectric conversion element for reading an image of a document, and storing the read image data in the first storage means. An image reading device that is a processing device.

Therefore, the image reading apparatus can have the same functions and effects as the invention according to any one of the first to fourth aspects.

According to a sixth aspect of the present invention, there is provided a printer engine for forming an image on a sheet based on the transferred image data, and the printer engine is a transfer destination of the DMA transfer. An image forming apparatus as the information processing apparatus according to any one of the above.

Therefore, the image forming apparatus can achieve the same functions and effects as those of the first to fourth aspects of the present invention.

According to a seventh aspect of the present invention, in the image forming apparatus according to the seventh aspect, a photoelectric conversion element for reading a document and outputting image data to be stored in the first storage means is provided.

Therefore, an image forming apparatus such as a copying machine can have the same functions and effects as the invention according to any one of the first to fourth aspects.

According to an eighth aspect of the present invention, there is provided a judging step of judging a characteristic of image data for each block obtained by dividing image data of one image into a plurality of blocks, and a step of judging the characteristics of each block in a format corresponding to the characteristic. A conversion step of converting image data, and an image data storage step of storing the converted image data of each block in the first storage means in accordance with the conversion.
Descriptors used when the image data is DMA-transferred from the first storage unit are provided for each of the blocks, including data used for returning each block to the image data before conversion in order to perform the DMA transfer. An image data storage method includes a descriptor creation step to be created and a descriptor storage step to store the created descriptor.

Therefore, each block can be returned to the image data before conversion by the descriptor, and the DMA transfer can be performed. Therefore, the image data of one image is divided into a plurality of blocks, and the image data is divided into different formats for each block. Even if the data is converted, the image data of one image can be DMA-transferred by one command.

The characteristics of the image data include, for example, that when compressed, the data amount is larger than that of the original image data, or that the image is an image of only white or black. Converting image data to a format according to characteristics includes, for example, image data compression.

According to a ninth aspect of the present invention, in the image data storing method according to the eighth aspect, the descriptor includes data indicating whether or not the block is compressed as data used in the processing. I have.

Therefore, it is possible to store the original image data for blocks whose data amount increases instead of compressing them, and to store them in the first storage means as compressed code data for blocks that do not.
The storage capacity of the first storage means can be saved, and the manufacturing cost can be reduced.

According to a tenth aspect of the present invention, in the image data storing method according to the eighth or ninth aspect, the descriptor is used to determine whether or not to execute data transfer from the first storage means as data used in the processing. Contains data indicating

Therefore, it is possible to prevent data transfer from the first storage means for a block of an image of only white or black, so that the image data of the block is stored in the first storage means. By omitting this step, the storage capacity of the first storage unit can be saved, and the manufacturing cost can be reduced.

According to an eleventh aspect of the present invention, in the image data storage method according to the tenth aspect, when the descriptor includes data indicating that the access is not executed, the descriptor is used as data used in the processing. The block includes data indicating that the block is a specific one-color image.

Therefore, for a block composed of an image of a specific color such as a single color of white or black, the color can be reproduced even if the image data is not stored in the first storage means.

The twelfth aspect of the present invention includes a reference step of referring to a descriptor, and a transfer step of DMA-transferring the image data stored in the first storage means based on the referenced descriptor. The image data is composed of a plurality of blocks obtained by dividing the image data of one image, and is selectively converted into a format according to the characteristics of the image data for each block. The descriptor is stored in the first storage means, and the descriptor includes data used for processing for returning each block converted in order to perform the DMA transfer to the image data before the conversion. Each transfer block is prepared for each block, and the transfer step refers to the data used for the processing and converts each of the blocks that have been converted into an image before the conversion. A DMA transfer method and performs the DMA transfer back to the data.

Therefore, since each block can be returned to the image data before conversion by the descriptor and the DMA transfer can be performed, the image data of one image is divided into a plurality of blocks, and each block is divided into a different format. Even if the data is converted, the image data of one image can be DMA-transferred by one command.

The characteristics of the image data include, for example, that when compressed, the data amount is larger than that of the original image data, or that the image is an image of only white or black. Converting image data to a format according to characteristics includes, for example, image data compression.

According to a thirteenth aspect of the present invention, in the DMA transfer method of the twelfth aspect, the descriptor includes data indicating whether or not the block is compressed as a type of the data.

Therefore, it is possible to store the original image data for blocks whose data amount increases instead of compressing them, and to store them in the first storage means as compressed code data for blocks that do not.
The storage capacity of the first storage means can be saved, and the manufacturing cost can be reduced.

According to a fourteenth aspect of the present invention, in the DMA transfer method according to the twelfth or thirteenth aspect, the descriptor indicates whether data transfer from the first storage unit is performed as the type of the process. Contains data.

Therefore, it is possible to prevent data transfer from the first storage means for a block of an image of a single color such as white or black, so that the image data of the block is stored in the first storage means. By omitting this step, the storage capacity of the first storage unit can be saved, and the manufacturing cost can be reduced.

According to a fifteenth aspect of the present invention, in the DMA transfer method according to the fourteenth aspect, when the descriptor includes data indicating that the access is not to be performed, the block is defined as the type of the data. Contains data indicating that the image is a specific one-color image.

Therefore, for a block composed of an image of a specific one color such as one color of white or one color of black, the color can be reproduced even if the image data is not stored in the first storage means.

[0045]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.

FIG. 1 is a conceptual diagram illustrating a schematic configuration of a digital copying machine 1 according to an embodiment of the present invention. The digital copying machine 1 implements the information processing apparatus, the image reading apparatus, and the image forming apparatus according to the present invention, and includes an image reading section 2, an image forming section 3, a facsimile section 4, a selector section 5, It includes a storage unit 6, an operation unit 7, and a system control unit 8.

The image reading section 2 exposes and scans the original G by an exposure lamp 12 movable along an original platen 11, and reflects the reflected light via a mirror 13-15 or other optical system to a CCD image as a photoelectric conversion element. The image of the document G is read by receiving light with the sensor 16. Then, in an IPU (image processing unit) 17, processing such as shading correction is performed on the image signal output from the CCD image sensor 16, A / D converted to an 8-bit digital signal, and scaling processing is performed. Image processing such as dither processing is performed. The processed image data is output together with the image synchronization signal. Scanner controller 1
Reference numeral 8 captures detection signals from various sensors and outputs control signals to actuators such as various drive motors in order to execute the process of the image reading unit 2 described above. Also, IP
Various parameters are set in U17.

Here, the image synchronization signal output from the IPU 17 of the image reading section 2 will be described with reference to the timing chart shown in FIG. That is, the frame gate signal (/ FGATE) is a signal indicating an image effective range for the image area in the sub-scanning direction, and image data is valid while this signal is at the L level (low active). The frame gate signal (/ FGATE) is asserted at the falling edge of the line synchronization signal (/ LSYNC), or
Negated. The line synchronization signal (/ LSYNC) is asserted for a predetermined number of clocks at the rising edge of the pixel synchronization signal (PCLK), and after the rising of this signal, the image data in the main scanning direction becomes valid after a predetermined clock. The transmitted image data is one for one cycle of the pixel synchronization signal (PCLK). The image data is sent out as raster format data starting from the arrow. The effective sub-scanning range of image data is usually determined by the size of the transfer paper.

As shown in FIG. 1, in the image forming section 3, which is a printer engine, the photosensitive member 22 is uniformly charged by the charging charger 21, and the charged photosensitive member 22 rotating at a constant speed is read. Exposure is performed with laser light modulated by the optical writing unit 23 based on the image data output from the unit 2 to form an electrostatic latent image. The electrostatic latent image on the photoreceptor 22 becomes a visible toner image by being developed with toner by the developing device 24. Then, the transfer paper, which has been fed in advance from the paper feed tray 26 by the paper feed roller 25 and is kept on standby by the registration roller 27, is transported at a timing with the photoconductor 22, and is transferred by the transfer charger 28. The upper toner image is electrostatically transferred to transfer paper. Thereafter, the transfer paper is separated from the photoconductor 22 by the separation charger 29, and the toner image on the transfer paper is fixed to the fixing device 30.
Is fixed by heating, and the discharge tray 31 is driven by the discharge roller 31.
2 is discharged. On the other hand, the toner remaining on the photoconductor 22 after the electrostatic transfer is removed by the cleaning device 33.
The photoconductor 21 is neutralized by the neutralization charger 34. The plotter control unit 35 captures detection signals of various sensors and outputs control signals to actuators such as various drive motors in order to execute the process of the image forming unit 3 described above. The image forming unit 3 can use not only the electrophotographic method as described above but also various printing formats such as an ink jet method.

The operation unit 7 includes various keys for receiving various operations from the user, an LCD display for displaying various messages to the user, and the like.

The system control unit 8 detects an input to the operation unit 7 by the user, and sets various parameters to the image reading unit 2, the storage unit 6, the image forming unit 3, and the facsimile unit 4, and issues a process execution instruction. Perform by communication.

The facsimile unit 4 converts the image data read by the image reading unit 2 according to an instruction from the system control unit 8 into G
(3) Binary compression is performed based on the G4 facsimile data transfer rules, and the data is transferred to the destination via a telephone line. Also,
Image data is received from the outside via a telephone line, and the image data is restored into binary image data, which is provided to the image forming unit 3 for image formation.

The selector unit 5 changes the state of the selector in accordance with an instruction from the system control unit 8 and
The source of the image data for forming the image is switched to an image signal output from any one of the image reading unit 2, the storage unit 6, and the FAX unit 4.

The storage unit 6 stores image data of the document G normally input from the IPU 17 and is used for a copy application such as a repeat copy and a rotation copy. It is also used as a buffer memory for temporarily storing the binary image data from the FAX unit 4. These data storage instructions are given by the system control unit 8.

Next, the detailed configuration of the storage unit 6 will be described with reference to FIG.

As shown in FIG. 3, the image input / output DMAC
(In the description of the embodiment of the present invention, “DMA controller” is simply referred to as “DMAC”) 41 is a CPU.
And a logic LSI, which communicates with the memory control unit 42 to receive a command, performs an operation setting according to the command, and transmits status information for notifying the state of the image input / output DMAC 41 itself. When an image input command is received, the input image data is packed as 8-pixel memory data according to the input image synchronization signal, and output to the memory control unit 42 together with the memory access signal as needed. When receiving an image output command, it outputs image data from the memory control unit 42 in synchronization with an output image synchronization signal.

The image memory 43 as the first storage means
A memory for storing image data, which is composed of a semiconductor storage element such as a DRAM. In this example, the total amount of memory is 400 dpi, which is four times the A3 size of binary image data.
A total of 8 Mbytes and 4Mbytes for storage of electronic sorts
MB. The image memory 43 includes a memory control unit 42
And read and write control.

The memory control unit 42 is composed of a CPU and a logic LSI, communicates with the system control unit 8 to receive a command, sets an operation according to the command, and notifies the state of the storage unit 6. Send status information.

The operation commands from the system control unit 8 include image input, image output, compression, decompression, and the like. Commands such as image input and image output include the image input / output DMAC 41.
Sent to. Commands such as compression and decompression are transmitted to the image transfer DMAC 44, code transfer DMAC 45, and compression / decompression unit 46, respectively.

FIG. 4 is a block diagram showing a detailed configuration of the memory control unit 42. As shown in FIG.
Reference numeral 7 denotes an image input / output DMAC 41 and an image transfer DMAC 4
4. Arbitrate the memory access request signal from the code transfer DMAC 45 and output an access permission signal. The memory control unit 42 has a built-in refresh control circuit 48, and the priority order is the refresh control circuit 48, the image input / output DMAC 4
1. In the order of the image transfer DMAC 44 and the code transfer DMAC 45, the memory access permission signal is actively output to the permission destination under the condition that the memory access of the image memory 43 is inactive. Further, it outputs an enable signal and selects an address of the image memory 43, and outputs a trigger signal indicating the start of memory access to the access control circuit 48.

The input physical address is determined by a signal from the access control circuit 48.
Are divided into a row address and a column address corresponding to the image memory 43 constituted by the image memory 43, and output to an 11-bit address bus. In accordance with the access start signal from the arbiter 47, the DRAM control signals (RAS, CAS, W
E) is output to the image memory 43.

The image transfer DMAC 44 is composed of a CPU and a logic LSI, communicates with the memory control unit 42 to receive a command, performs an operation setting according to the command, and sets a state as shown in FIG. Is transmitted as status information to inform the user. When a compression command is received, a memory access request signal is output to the memory control unit 42. When the memory access permission signal is active, image data is received and transferred to the compression / expansion unit 46. Further, it incorporates an address counter that counts up in response to a memory access request signal, and outputs a 22-bit memory address indicating a storage location where image data is stored.

The code transfer DMAC 45 is composed of a CPU and a logic LSI, communicates with the memory control unit 42, receives a command, sets an operation in accordance with the command, and transmits it as status information to notify a state. I do. When a decompression command is received, a memory access request signal is output to the memory control unit 42, and when the memory access permission signal is active, image data is received and transferred to the compression / decompression unit 46. Further, it incorporates an address counter that counts up in response to a memory access request signal, and outputs a 22-bit memory address indicating a storage location where image data is stored.

The compression / expansion unit 46 includes a CPU and a logic L
It is configured with an SI, communicates with the memory control unit 42, receives a command, performs operation setting according to the command,
Also, it is transmitted as status information to inform the state. The compression / expansion unit 46 compresses the binary image data by the MH encoding method.

The image data read by the image reading unit 2,
The image data received by the FAX unit 4 is transmitted to the system control unit 8
Instructs the storage unit 6 to store it in a predetermined image area of the image memory 43. Then, the CPU of the memory control unit 42
One image data stored in the image memory 43 is divided into a plurality of blocks in the sub-scanning direction of the image, and is divided into image transfer DMAs.
C44, the image data is sequentially read out by the compression / expansion unit 46, and then compressed again by the code transfer DMAC 45.
Is written in a predetermined storage area. Thereafter, the memory control unit 4
2 notifies the system controller 8 of the processing result, and the CPU of the system controller 8 creates descriptors A, B,... As shown in FIG. A plurality of descriptors A, B,.
Is stored in the second storage means constructed in a predetermined area of the RAM of the system control unit 8.

Each of the descriptors A, B,... Is composed of four words, a chain destination address indicating a storage address of the next descriptor, a data transfer destination address indicating a head address of data to be transferred, and a data to be transferred. The number of data transfer words that indicates the data amount of the
And format information indicating the format of the data to be transferred.

When one piece of image data stored in the image memory 43 is divided into a plurality of blocks and compressed by the compression / expansion unit 46, the code transfer DMAC 45 counts the amount of code data, If the data amount exceeds the original image data amount, the above operation is interrupted, the block is passed from the beginning of the block without passing through the compression / expansion unit 46, and sent back to the code transfer DMAC 45, and the original image not compressed is sent. The data is stored in the image memory 43 as it is.

As described above, each block is stored in the image memory 43 in the form of code data obtained by compressing image data or intact image data which has not been subjected to compression processing. In this case, based on the notification from the memory control unit 42, the system control unit 8 recognizes whether the image data of each block is code data obtained by compressing the image data or image data that has not been subjected to the compression processing. Another descriptor is recorded in the least significant bit (compression presence / absence bit) of the format information (see FIG. 5) of the descriptor corresponding to each block. For example, when the compression presence / absence recognition bit is 1, it indicates image data that has not been subjected to compression processing, and when it is 0, it indicates code data.

The image transfer DMAC 44 checks whether or not the image data of each block to be sent to the compression / expansion unit 46 is composed of white data of one white color or black data of one black color. When there is a block composed of white data of only white or black data of single black, the memory control unit 42
Clears the image data of the block stored in the image memory 43 and notifies the system control unit 8. In this case, whether to access the image memory 43 or not (1 bit) also to the two higher bits than the compression presence / absence recognition bit, and to generate white data when not accessing the image memory 43 , Generate a descriptor in which bits indicating whether to generate black data (1 bit) are arranged. The former one bit is called a memory access presence / absence recognition bit, and the latter one bit is called a color recognition bit. Regarding the former access to the image memory 43, the memory access presence / absence recognition bit is assumed to be accessed by 0, and when it is 1, the access is not performed and the value of the color recognition bit is reflected.
When the color recognition bit is 0, the transfer of white data is performed, and when the color recognition bit is 1, the transfer of black data is performed instead of the transfer of the image data stored in the image memory 43.

The process of transferring image data to the image memory 43 and creating a descriptor performed by the system control unit 8 and the storage unit 6 as described above will be described with reference to the flowchart of FIG. That is, the system control unit 8 transmits one image data to the storage unit 6, and the memory control unit 42 stores the image data in the image memory 43 (step S1). Then, the single image data is divided into a plurality of blocks, and when the code data amount after compression is smaller than the original image data amount as described above (N in step S2), the image data is compressed. Stored in the image memory 43 (step S3),
If it exceeds (Y in step S2), the image data is stored in the image memory 43 without compression (step S2).
4).

If there is a block composed of white data of one white color or black data of one black color (Y in step S5), the image data of the block stored in the image memory 43 is stored as described above. Is cleared (step S6). Then, the system control unit 8 stores the information in steps S2 to S
The result of the process 5 is notified (step S7).

By the steps S2 and S3, the characteristics of the image data such as whether or not the code data amount after compression exceeds the original image data amount and whether the image data is composed of white data of one white color or black data of one black color are obtained. Judgment is made for each block (thus, a judgment means and a judgment step are realized). Further, in step S3, the image data for each block is converted into a format in which the data is compressed and converted into code data according to the characteristic that the amount of code data after compression exceeds the amount of original image data. , The conversion process is realized). In this case, if the image data is composed of white data of only one color or black data of one black, the image data is cleared in step S6. Therefore, the conversion of the image data for each block is selectively performed. The storage of the image data for each block is also performed in accordance with the conversion of the image data for each block. Further, step S
The image data storage step is realized by 3 and S4.

Based on this notification, the system control unit 8 creates a plurality of descriptors A, B,... For each block (step S8) and stores them in the second storage means of the RAM (step S9). Step S8 implements a descriptor creation means and a descriptor creation step, and step S9 implements a descriptor storage step. In this case, based on the notification, the values are set in the descriptors A, B,... For the compression presence / absence recognition bit, the memory access presence / absence recognition bit, and the color recognition bit for each block as described above.

The compression presence / absence recognition bit, the memory access presence / absence recognition bit, and the color recognition bit
3, data used for processing to return to the original image data before performing the processing of S6. That is, the compression presence / absence recognition bit indicates whether the block has been compressed, the memory access presence / absence recognition bit indicates whether data transfer from the image memory 43 has been performed, and the color recognition bit has
When the transfer of data from block No. 3 is not performed, the block indicates a specific color, that is, white data or black data.

FIG. 7 is a block diagram for explaining the configuration of the code transfer DMAC 45. As shown in FIG. 7, the code transfer DMAC 45 includes a data transfer control unit 51 that controls the transfer of image data, and a descriptor storage register 52 that stores a descriptor.

The image data 53 shown in FIG. 8 is for one image after the processing described with reference to FIG.
For example, it is divided into four blocks a to d. In this example, it is assumed that the block a is code data obtained by normally compressing image data. In block b, since the compression ratio exceeds 1, and the data amount becomes larger than the image data before compression, it is assumed that the original image data remains unchanged. In the block c, no image is included in the image data, the entire image is solid white, the storage area is not secured in the image memory 43, and the data transfer of the white data is performed only by the data transfer control unit 51. (Described later). Therefore, the data of the block c is not stored in the image memory 43. Further, it is assumed that the block d is divided into memory areas designated by two descriptors during compression (blocks d1 and d2) and image data is stored.

The data in which these plural data formats are mixed are described below by code transfer DMA using a descriptor.
A procedure in which the C45 performs a series of DMA transfers will be described with reference to a flowchart of FIG. First, when the CPU of the memory control unit 42 receives the decompression command from the system control unit 8 (Y in step S11), the DMA starts (step S12). Read access is made to the descriptor storage register 52 with the chain destination address of the descriptor A set by the CPU in advance, and the descriptors A, B,... Stored in the second storage means in the RAM of the system control unit 8 are read. Is loaded into the descriptor storage register 52 of the code transfer DMAC 45 (step S13).

As described above, the compression presence / absence recognition bit of the format information is a bit indicating whether the data to be transferred is code data obtained by compressing image data or image data that has not been subjected to compression processing. When the image data has not been subjected to the compression processing, the image data has been processed. As described above, the memory access presence / absence recognition bit and the color recognition bit indicate whether the former accesses the image memory 43 or not, and the latter generates white data when the image memory 43 is not accessed. Or whether to generate black data.

Then, the data transfer control unit 51 determines the value of the memory access presence / absence recognition bit of the format information of the first descriptor A (step S14). If there is no memory access to the image memory 43 based on the value of the memory access presence / absence recognition bit (Y in step S14), the value of the color recognition bit is determined (step S1).
5). Then, without accessing the image memory 43, white data or black data of a fixed gradation is DMA-transferred to the image forming unit 3 via the image input / output DMAC 41 according to the value of the color recognition bit (step S16). , S1
7).

If there is memory access to the image memory 43 from the value of the memory access presence / absence recognition bit (N in step S14), the value of the compression presence / absence recognition bit is determined (step S18). If the head block is the compressed code data from the compression presence / absence recognition bit (Y in step S18), the data of the block in the image memory 43 is transmitted to the compression / decompression unit 46 to return to the original image data. Thereafter, DMA transfer is performed to the image forming unit 3 via the image input / output DMAC 41 (step S19). The presence or absence of compression is determined from the memory access presence / absence recognition bit (step S
18) If there is no compression (N in step S18), the image data in the image
Transfer (step S20). The processing from step S14 onward is repeated (N in step S21) until DMA transfer is completed for all blocks (Y in step S21).

The reference process is realized by steps S14, S15, S16, and steps S16, S17, S19, S20
Since these methods refer to a descriptor and perform DMA transfer of image data based on this descriptor, the reference step and the transfer step are realized.

According to the digital copying machine 1 described above,
Even if each block obtained by dividing one piece of image data is compressed for each block or is cleared and held, each block can be compressed and returned to the original image data before clearing by the descriptor, and DMA transfer can be performed. Therefore, the image data of one image can be DMA-transferred by one decompression command.

Further, it is possible to store the original image data for blocks whose data amount increases instead of compression by the compression presence / absence recognition bit, and to store them in the image memory 43 as compressed code data for blocks that do not. Thus, the storage capacity of the image memory 43 can be saved, and the manufacturing cost can be reduced.

Further, for a block of an image such as a single white color or a single black color, data transfer from the image memory 43 can be prevented by the memory access presence / absence recognition bit. By omitting the storage in the image memory 43 by the recognition bit, the storage capacity of the image memory 43 can be saved by the memory access presence / absence recognition bit, and the manufacturing cost can be reduced.

In this case, for a block composed of an image of a specific color, such as a single color of white or black, even if the storage of the image data in the image memory 43 is omitted, the color can be reproduced by the color recognition bits. it can.

[0086]

According to the first aspect of the present invention, each block is returned to the image data before conversion by the
Since the A transfer can be performed, even if the image data of one image is divided into a plurality of blocks and the image data is converted into a different format for each block, the image data of one image is DMA transfer can be performed by a command.

According to a second aspect of the present invention, in the information processing apparatus according to the first aspect, blocks whose data amount increases instead of being compressed remain original image data, and blocks which are not compressed are compressed. It can be stored as code data in the first storage means,
The storage capacity of the first storage means can be saved, and the manufacturing cost can be reduced.

The third aspect of the present invention is the first or second aspect.
In the information processing apparatus described in the item (1), data transfer from the first storage unit can be made not to be performed for an image block such as a white color or a black color, so that the image data of the block is stored in the first storage unit. By omitting the storage in the means, the storage capacity of the first storage means can be saved, and the manufacturing cost can be reduced.

According to a fourth aspect of the present invention, in the information processing apparatus according to the third aspect, a block including a specific one-color image such as a single-color image or a single-color image is stored in a first storage unit of the image data. Can be reproduced even if the memory is omitted.

According to the fifth aspect of the present invention, the image reading apparatus can provide the same functions and effects as those of the first to fourth aspects of the present invention.

According to the sixth aspect of the present invention, the image forming apparatus can provide the same operation and effect as those of the first to fourth aspects of the present invention.

According to the seventh aspect of the invention, an image forming apparatus such as a copying machine can have the same functions and effects as those of the first to fourth aspects of the invention.

According to an eighth aspect of the present invention, each block is returned to the image data before conversion by using
Even if the image data of one image is divided into a plurality of blocks and the image data is converted into a different format for each block, the image data of one image can be transferred by one command. Can be used for DMA transfer.

According to a ninth aspect of the present invention, in the image data storage method according to the eighth aspect, blocks whose data amount increases instead of being compressed remain original image data, and blocks which are not compressed are compressed. This makes it possible to store the encoded data in the first storage means, thereby saving the storage capacity of the first storage means and reducing the manufacturing cost.

According to a tenth aspect of the present invention, in the image data storage method according to the eighth or ninth aspect, data transfer from the first storage means is not performed for an image block such as a white color or a black color. So that you can
By omitting storing the image data of the block in the first storage means, saving the storage capacity of the first storage means,
Manufacturing costs can be reduced.

According to an eleventh aspect of the present invention, in the image data storage method according to the tenth aspect, a first storage means for storing image data of a block composed of a specific one-color image such as a white color or a black color. The color can be reproduced even if the memory is omitted.

According to the twelfth aspect of the present invention, each block is returned to the image data before conversion by the
Since the A transfer can be performed, even if the image data of one image is divided into a plurality of blocks and the image data is converted into a different format for each block, the image data of one image is DMA transfer can be performed by a command.

According to a thirteenth aspect of the present invention, in the DMA transfer method according to the twelfth aspect, blocks whose data amount increases instead of being compressed remain original image data and blocks which are not compressed are compressed. Code data can be stored in the first storage means, so that the storage capacity of the first storage means can be saved and the manufacturing cost can be reduced.

According to a fourteenth aspect of the present invention, in the DMA transfer method according to the twelfth or thirteenth aspect, data transfer from the first storage means is not performed with respect to an image block such as a white color or a black color. So that
By omitting storing the image data of the block in the first storage means, saving the storage capacity of the first storage means,
Manufacturing costs can be reduced.

According to a fifteenth aspect of the present invention, there is provided the DMA transfer method according to the fourteenth aspect, wherein the DMA transfer method comprises the steps of:
For a block composed of a specific one-color image, the color can be reproduced even without storing the image data in the first storage means.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a digital copying machine according to an embodiment of the present invention.

FIG. 2 is a timing chart showing an image synchronization signal output from an IPU of the digital copying machine.

FIG. 3 is a block diagram illustrating a detailed configuration of a storage unit of the digital copying machine.

FIG. 4 is a block diagram illustrating a detailed configuration of a memory control unit of the storage unit.

FIG. 5 is a block diagram illustrating a data structure of a descriptor used for DMA transfer performed by the storage unit.

FIG. 6 is a flowchart illustrating a process of creating the disk revoter and a process of storing image data in an image memory.

FIG. 7 is a block diagram illustrating a detailed configuration of a code transfer DMA controller of the storage unit.

FIG. 8 is an explanatory diagram illustrating a plurality of blocks constituting one piece of image data.

FIG. 9 is a flowchart illustrating a DMA transfer process performed by the storage unit.

[Explanation of symbols]

 1 Information Processing Apparatus, Image Reading Apparatus, Image Forming Apparatus 43 First Storage Means 45 DMA Controller 53 Image Data

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G06T 1/60 450 G06T 1/60 450E 5C062 H04N 1/00 H04N 1/00 C 5C073 1/21 1/21 5C076 1/387 1/387 (72) Inventor Yasumitsu Shimizu 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Norio Michiya 1-3-6 Nakamagome, Ota-ku, Tokyo Share F-term within Ricoh Company (reference) 2C087 AA03 AA09 BA03 BA07 BA14 BB10 BD10 BD40 BD41 CA13 2C187 AD03 5B021 AA19 BB11 BB12 DD04 QQ04 5B047 AA01 BB02 CA21 CB22 DC09 EB15 EB17 5B061 BA03 AC05 AB03 AC05 AB03 AC05 BB02 CE01 5C076 AA36 BA03 BA05 BA06 BA09

Claims (15)

[Claims] 1. A determining means for determining characteristics of image data for each block obtained by dividing image data of one image into a plurality of blocks, and selectively converting the image data of each block into a format according to the characteristics. Conversion means for performing the conversion, first storage means for storing the image data of each block after the conversion in accordance with the conversion, and a descriptor used for DMA transfer of the image data from the first storage means, Descriptor creating means for creating each block including data used for processing for converting the converted blocks to the image data before the conversion to perform the DMA transfer, and a second storage for storing the descriptors Means for returning each block to the image data before conversion based on the data used in the processing included in the descriptor. D performed based DMA transfer of the image data composed of the plurality of blocks to the disk pre descriptor
An information processing apparatus, comprising: an MA controller, for performing a process using the image data. 2. The information processing apparatus according to claim 1, wherein the descriptor includes, as data used in the processing, data indicating whether the block is compressed. 3. The information processing apparatus according to claim 1, wherein the descriptor includes, as data used for the processing, data indicating whether data transfer from the first storage unit is performed. 4. When the descriptor includes data indicating that the access is not executed, the descriptor includes data indicating that the block is a specific one-color image as data used in the processing. Item 4. The information processing device according to item 3. 5. An image reading apparatus as an information processing apparatus according to claim 1, further comprising a photoelectric conversion element for reading an image of a document, and storing the read image data in said first storage means. . 6. The information according to claim 1, further comprising a printer engine for forming an image on a sheet based on the transferred image data, wherein the printer engine is a transfer destination of the DMA transfer. An image forming apparatus which is a processing apparatus. 7. The image forming apparatus according to claim 6, further comprising: a photoelectric conversion element for reading a document and outputting image data to be stored in the first storage unit. 8. A judging step of judging a characteristic of the image data for each block obtained by dividing the image data of one image into a plurality of blocks, and a converting step of converting the image data of each block into a format according to the characteristic. An image data storing step of storing the converted image data of each block in a first storage means in accordance with the conversion; and a descriptor used when the image data is DMA-transferred from the first storage means. A descriptor creation step of creating, for each of the blocks, data including data used for returning each block to the image data before conversion in order to perform the DMA transfer; and a descriptor storage step of storing the created descriptor. And a method for storing image data. 9. The image data storage method according to claim 8, wherein the descriptor includes data indicating whether or not the block is compressed as data used in the processing. 10. The descriptor includes data indicating whether or not data transfer from the first storage unit is to be executed, as data used for the processing.
2. The image data storage method according to 1. 11. When the descriptor includes data indicating that the access is not executed, the descriptor includes data indicating that the block is a specific one-color image as data used for the processing. Item 10
2. The image data storage method according to 1. 12. A reference step of referring to a descriptor, and a transfer step of DMA-transferring image data stored in the first storage means based on the referenced descriptor, wherein the image data is A plurality of blocks obtained by dividing the image data of one image, and selectively converted into a format corresponding to the characteristics of the image data for each block, and stored in the first storage means in accordance with the conversion. The descriptor is prepared for each of the blocks, including data used for returning each converted block to the image data before the conversion in order to perform the DMA transfer. The transfer step is to return the converted blocks to the image data before the conversion with reference to the data used for the processing, the DMA transfer method is to perform the MA transfer. 13. The DMA transfer method according to claim 12, wherein the descriptor includes data indicating whether or not the block is compressed as a type of the data. 14. The DMA transfer method according to claim 12, wherein the descriptor includes, as a type of the processing, data indicating whether or not data transfer from the first storage unit is performed. 15. When the descriptor includes data indicating that the access is not executed, the descriptor includes data indicating that the block is a specific one-color image as a type of the data. 15. The DMA transfer method according to 14.