JPH0927038A - Method and device for storing image data, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the productivity of a copy without increasing the capacity of a buffer memory. SOLUTION: By this storing method for image data, image data read by an image input part 10 are compressed and then transferred to and stored in a storage unit, and the compressed image data are optionally read out of the storage unit 25 are outputted to an image output part 30 at need after being expanded. Then this method includes the process wherein the image data read by the image input part 10 are compressed by an image compression and expansion part 22 in the input order and stored in the buffer memory 23, the process wherein a specific amount of data are transferred to and stored in the storage unit 25 as one block each time the stored data reaches the specific amount, and a process wherein data of plural transferred blocks are controlled, page by page.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to compressing and accumulating image data from an input means such as a scanner, reading out and compressing arbitrary compressed image data, and generating an image based on the expanded image data. The present invention relates to an image data storage method for outputting or forming, a storage device thereof, and an image forming apparatus.

[0002]

2. Description of the Related Art Recently, digital copying machines have been equipped with electronic RDs.
A function called H (Electronic Recirculating Document Handler) has been incorporated. Such an electronic RDH performs a copying operation for an arbitrary number of copies in a state in which a plurality of originals are sorted. For the first copy, the originals are read one by one with a scanner and the image output unit While the image is formed based on the image data and the storage device stores the image data, the second and subsequent copies are read in the order in which the stored image data is read, and based on the read image data. It is realized by forming an image. Therefore, in order to perform electronic RDH, a large-capacity storage device for storing image data is required. As is well known, there are various types of such storage devices, but a hard disk having a low unit price per storage capacity is used in a digital copying machine having an electronic RDH function.

Here, it is assumed that the transfer speed of image data output from an image input unit such as a scanner (or the transfer speed of image data supplied by the image output unit) is m, and the access speed to a storage device is n. , M / n times the speed difference occurs. Such speed difference is usually m> n. Further, when image formation is started in the image output section, the operation cannot be stopped. Therefore, the read operation cannot be intermittently driven in synchronization with the storage operation for data transfer to the storage device.

Therefore, conventionally, in order to absorb the speed difference, the read image data is compressed until the data amount can be written at the access speed to the storage device. Here, since the compressed data cannot be directly transferred to the storage device, a buffer memory having an access speed that is overwhelmingly higher than that of the hard disk is inserted between the compression device and the storage device for performing compression, and the compressed data is transferred in page units. When the compressed data is stored for a predetermined number of pages and the compressed data is stored for a predetermined number of pages, the compressed data is transferred and stored in the storage device in synchronization. On the other hand, when the compressed data corresponding to the desired page is read from the storage device and the image data is transferred to the image output unit, a similar speed difference occurs. In order to absorb such a speed difference, one page of compressed data read from the storage device is stored in the above-mentioned buffer memory, and at that point, decompression processing is performed for sequential decoding, and image data is decoded according to the decoded image data. The image is formed by the image output unit.

[0005]

In the buffer memory described above, the capacity of compressed data for one page is limited due to the necessity of good synchronization, the difference in document size, the variation in compression ratio, and the like. In consideration of the difference and the like, it is desirable to have a certain amount of capacity and to provide a dedicated storage device corresponding to each input / output of the storage device. In particular, considering that it can be synchronized with the reading operation of the image input section and the image forming operation of the image output section, if data for many pages can be stored at one time, the waiting time for data transfer to the storage device can be greatly shortened. Is possible. However,
Since the increase in capacity directly invites the high cost of the entire apparatus, it is currently required that the increase be minimized. In addition, if the capacity has a certain margin, the access frequency to the storage device surely decreases, but when the image data is generated to the extent that the capacity is exceeded, in order to prevent the loss of the image data, at a point before the excess, The transfer of the image data to the storage device must be started. That is, the measure of increasing the capacity of the buffer memory cannot fundamentally solve the problem of shortening the waiting time for data transfer to the storage device.

In addition, when the data stored in the buffer memory is transferred to the storage device, it is necessary to prepare for storing the next data. Here, if a hard disk is used as the storage device, data transfer is
A predetermined standard (for example, SCSI (Small Computer Seste
m Interface) standard). In such a protocol, transfer to a storage device is generally not possible unless the amount of data to be transferred is fixed. Therefore, if the compressed data for one page is not stored, the transfer to the storage device cannot be started, and it becomes difficult to access the storage device in synchronization with the operations of the image input unit and the image output unit. For the above reason, if the capacity of the buffer memory is increased, the copying operation can be performed at a high speed, and the productivity of the copy is improved, but the cost is increased, and conversely, the buffer memory Cost can be kept low by reducing the capacity,
There is a conflicting problem that the copying operation becomes slow and the productivity of the copied product is reduced.

The present invention has been made in view of the above problems, and an object of the present invention is to store an image data and an image in which the productivity of a copy is improved without increasing the capacity of the buffer memory. An object of the present invention is to provide a data storage device and an image forming apparatus having the same main part of the device configuration.

[0008]

In order to solve the above-mentioned problems, in the invention described in claim 1, after the image data read by the image input means is compressed by the compression means, the transfer speed is set to While transferring and storing to the first storage unit having an upper limit, the compressed image data is arbitrarily read from the first storage unit as needed, and the image data is expanded after being expanded by the expansion unit. In a method of storing image data to be output to an output unit, the image data is compressed by the compression unit in the order of input and stored in a second storage unit having a gentler upper limit of transfer rate than the first storage unit. And a second step of arbitrarily dividing the data stored in the second storage means into blocks, and transferring and storing each block in the first storage means. It is characterized by comprising a third step of managing data of a plurality of blocks in units of pages.

According to the second aspect of the present invention, the image data read by the image input means is compressed by the compression means, and then transferred to the first storage means having an upper limit of transfer rate for storage. , The compressed image data is arbitrarily read from the first storage means as needed, and the image data is stored in a storage device for the image data which is expanded by the expansion means and then output to the image output means. A second storage unit for compressing and storing in the input order by the compression unit, the second storage unit having a gentler upper limit of transfer rate than the first storage unit, and the second storage unit. The stored data is arbitrarily divided into blocks, and write control means for transferring and storing the data in the first storage means for each block, and the transferred data of a plurality of blocks in page units. It is characterized by comprising a management unit for management. According to the invention of claim 3,
In the invention of claim 2, the write control means is
Each time the amount of data stored in the second storage unit reaches a predetermined amount, the predetermined amount of data is transferred to the first storage unit as one block and stored therein. In the invention according to claim 4, in the invention according to claim 2 or 3, the first storage means, the second storage means, the write control means, or the management means, respectively, It is characterized in that storage, storage, transfer, or management is performed in synchronization with the image input means and the image output means. According to a fifth aspect of the present invention, in the second aspect of the present invention, the data of a plurality of blocks forming an image for one designated page is converted into the first block.
The storage means is read out in the order of storage and the second
Read control means for storing in the storage means of
The storage means is characterized in that the stored data amount is transferred to the decompression means every time the data amount when decompressed is determined. In the invention according to claim 6, in the invention according to claim 5, the first storage means, the second storage means, the writing means, the management means, or the read control means is Storage, storage, transfer, management, or reading are performed in synchronization with the image input means and the image output means, respectively. According to a seventh aspect of the present invention, in the second aspect of the present invention, the transfer speed at which the image data is output from the image input means and the compressed image data are stored in the first storage means. It is characterized by further comprising parameter setting means for setting a parameter for determining a compression rate in the compression means in accordance with a transfer speed at which the image data is expanded or a transfer speed at which the expanded image data is transferred to the image output means.

According to another aspect of the present invention, the image data read by the image input means is compressed by the compression means and then transferred to the first storage means having an upper limit of transfer rate for storage. , The compressed image data is arbitrarily read from the first storage means as needed, and the image data is stored in a storage device for the image data which is expanded by the expansion means and then output to the image output means. A second storage unit for compressing and storing in the input order by the compression unit, the second storage unit having a gentler upper limit of transfer rate than the first storage unit, and the second storage unit. The stored data is arbitrarily divided into blocks, and write control means for transferring and storing the data in the first storage means for each block, and the transferred data of a plurality of blocks in page units. And management means for management, has been designated 1
Read control means for reading the data of a plurality of blocks forming an image for a page from the first storage means in the stored order and storing the read data in the second storage means; and the second storage means. Each time the stored data amount is decompressed, the transferred data amount is transferred to the decompression unit, and the image output unit reconstructs an image based on the image data decompressed by the decompression unit. It is characterized by performing formation.

According to the first aspect of the invention, in the first step, the image data is compressed in the input order by the compression means and stored in the second storage means, and in the second step,
The data stored in the second storage means is arbitrarily divided into blocks, and for each block, transferred to the first storage means and stored therein. In the third process, the transferred data of a plurality of blocks is stored. It is managed in page units. Therefore, in the second storage means, it is not necessary to wait for transfer until one page of data is stored, and when the blocks are complete, the first storage is completed.
Since the data can be transferred to the storage means, the transfer waiting time can be shortened.

According to the second aspect of the present invention, the second storage means stores the image data after being compressed by the compression means in the input order, and the write control means stores in the second storage means. The divided data is arbitrarily divided into blocks, and each block is transferred to and stored in the first storage unit, and the management unit manages the transferred data of a plurality of blocks in page units. Therefore, in the second storage means, it is not necessary to wait for the transfer until one page of data is stored, and the data can be transferred to the first storage means at the time when the blocks are completed. Can be shortened. Further, according to the invention of claim 3, the write control means is
Each time the amount of data stored in the second storage means reaches a predetermined amount, the predetermined amount of data is transferred to and stored in the first storage means as one block. The transfer to the first storage means is performed in parallel. As a result, the amount of data itself stored in the second storage means is small. Therefore, the capacity required as the second storage means can be reduced.
According to the fifth aspect of the present invention, the reading control means reads the data of a plurality of blocks forming the designated image for one page from the first storage means in the order of storage and reads the second data. The data is stored in the storage means, and the second storage means stores the stored data each time the data amount when expanded is determined.
Since the data of the data amount is transferred to the decompression means, and the decompression means decompresses the transferred data and outputs the image data to the image output means, the reading from the first storage means and the second The storage in the storage means is performed in parallel. Further, reading of data from the first storage means is performed for each block. Therefore, even when the data stored in the first storage unit is read out, the capacity required as the second storage unit can be reduced and the transfer standby time can be shortened. Claim 7
According to the invention described in (1), since the compression rate is set according to each transfer time, when the data to be compressed is supplied from the image input means, or the data after the expansion processing is sent to the image output means. When supplied, the loss of image data is prevented in advance. According to the invention described in claim 4 or 6, the operation of each unit can be performed in synchronization with the image input means and the image output means.

According to the invention described in claim 8, it is not necessary to wait for the transfer until the data for one page is stored in the second storage means, and when the blocks are arranged, the first storage means is provided. Can be transferred to. Furthermore, since the storage in the second storage means and the transfer to the first storage means are performed in parallel, the amount of data itself stored in the second storage means is small. Therefore, it is possible to perform the image formation while shortening the transfer standby time and reducing the capacity required as the second storage means.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the present embodiment. As shown in this figure, the present embodiment is roughly divided into an image input unit 10, an image storage unit 20, and an image output unit 30. The image input unit 10 is composed of a scanner or the like, reads a document page by page, and outputs image data.
Forms an image for one page by, for example, laser light. Therefore, the image output unit 30 cannot temporarily stop the forming operation during the image formation. Further, at the time of reading an image, since image formation is also performed in synchronization with the reading operation, the reading operation of the image input unit 10 cannot be temporarily stopped after all. That is, the image input unit 10 and the image output unit 30 need to be synchronized with each other without pausing. SYNC is a synchronization signal therefor.

The image storage unit 20 is composed of the following units. First, reference numeral 21 is a line buffer,
Actually, a so-called ping-pong buffer is composed of two buffers that store image data for eight lines. Next, reference numeral 22 is an image compression / expansion unit that compresses the image data and expands the compressed data to the original image data. The compression / expansion algorithm used in the image compression / expansion unit 22 is, for example, JPE.
The one for still images recommended by G (Joint Photographic Experts Group) is used. Such an algorithm can maintain high image quality by compressing image data with a small compression rate and decompressing (decoding) this, but if compressed with a large compression rate and decompressing, the image quality of the image becomes low. Has irreversibility.

The operations of the line buffer 21 and the image compression / expansion unit 22 during compression / expansion will be briefly described below. When compressing the image data output from the image input unit 10, one of the line buffers 21 stores the image data and performs block scan conversion, while the other buffer stores images in the order of the converted blocks. The data is supplied to the image compression / decompression unit 22. Next, when the image data for one block (that is, for eight lines) is compressed by the image compression / expansion unit 22, the connection of the buffer is switched, and the other buffer is switched to the image input unit 10.
While storing the image data from and performing the block scan conversion, one buffer supplies the image data to the image compression / expansion unit 22 in the order of the converted blocks. Thereafter, this operation is repeated. With such a configuration, the image data supplied from the image input unit 10 in synchronization with the synchronization signal SYNC can be continuously compressed without pausing.

On the other hand, the compressed data is expanded by the image compression / expansion unit 22.
When decompressed by the image output unit 30, one buffer stores the image data decompressed by the image compression / decompression unit 22, while the other buffer synchronizes the stored data with the image output device 30. Read and supply. Next, one block of image data is converted into the image output device 3
When it is supplied to 0, the connection of the buffer is switched, and the other buffer stores the image data expanded by the image compression / expansion unit 22, while the one buffer transfers the stored data to the image output device 30. It is read and supplied in synchronization. Thereafter, this operation is repeated. With such a configuration, the expanded image data is output to the image output unit 3
Sync signal SYNC continuously without pausing to 0
It is possible to supply in synchronization with.

Next, reference numeral 23 is a buffer memory,
When the data compressed by the image compression / expansion unit 22 is transferred to the storage unit 25, or when the data stored in the storage unit 25 is transferred to the image compression / expansion unit 22, the data is temporarily divided into blocks. To be stored in. As the storage unit 25, a hard disk that can store a large amount of data and is relatively inexpensive is used, as in the conventional case. Reference numeral 24 is a storage control unit, which controls the transfer procedure of the storage unit 25. Reference numeral 26 is a control unit, which controls each unit via the system bus 27. Sign 2
Reference numeral 8 is a data bus through which image data or compressed data is transferred.

By the way, the transfer procedure of the storage unit 25 is performed based on the SCSI standard. Therefore, the buffer memory 23 and the storage unit 25
The data transfer rate during this period is about 3 Mbytes / s. On the other hand, the image compression / expansion unit 22 operates in synchronization with the synchronization signal SYNC, and the buffer memory 23, unlike the storage unit 22, stores and reads data purely electronically. The transfer rate between the output unit 30 and the buffer memory 23 is about 30 Mbytes /
s. Therefore, there is a speed difference of about 10 times. In order to absorb this speed difference, the control unit 2
A control unit 6 controls the image compression / expansion unit 22 so as to perform compression processing for reducing the image data from the image input unit 10 to 1/10 or less. Further, the control unit 26 controls the image input unit 10 and the image output unit 3 even if the document size changes.
The image compression / decompression unit 22 is configured so that the image data transferred between 0s is compressed at a compression rate that does not cause an overflow when compressed and transferred between the buffer memory 23 and the storage unit 25. It also controls the compression process.

Next, the operation of this embodiment will be described. First, the process until the image data output from the image input unit 10 is stored in the buffer memory 23 will be described. FIG. 2 is a flowchart showing the process. First, in step Sa1, the control unit 26
Sets the storage position where the compressed image data should be stored in the buffer memory 23. Here, the buffer memory 2
3 stores the image data at address positions that continuously increase.

Then, in step Sa2, the image input section 10 reads one original and outputs the image data, and then in step Sa3, the image compression / expansion section 22 compresses the image data. And the control unit 2
6 stores the compressed image data at the set storage position (step Sa4), and the control unit 2
6 holds the end position where the data is stored (step Sa5). Then, in step Sa6, the control unit 26 determines whether or not the input of the document is completed.

If the result of this determination is "No", the control unit 26 sets the position next to the held end position as the data storage position in step Sa7. On the other hand, if the determination result is “Yes”, the control unit 26 ends this operation. That is, image reading by the image input unit 10, compression processing by the image compression / expansion unit 22, and data storage in the buffer memory 23 are performed in synchronization with each other. This means that the data has been compressed and the storage in the buffer memory 23 has ended. Therefore, the control unit 26 ends the storage operation when the data input in the image input unit 10 is completed. As described above, the image data output from the image input unit 10 is compressed in synchronization with the reading operation and sequentially stored in the buffer memory 23.

Next, steps required until the data stored in the buffer memory 23 are stored in the storage unit 25 will be described. FIG. 3 is a flowchart showing the process. This step is a read operation performed in parallel with the storage operation in the buffer memory 23 shown in FIG. 2, and shows the transfer operation to the storage unit 25. The transfer to the storage unit 25 is performed under the control of the storage control unit 24.
Are under the control of the control unit 26. First, the control unit 26 sets the block size at the time of transferring the stored compressed data to the storage unit 25 in step Sb1. In the present embodiment, the transfer of the compressed data between the buffer memory 23 and the storage unit 25 is performed by dividing the compressed data corresponding to one page into blocks and subdividing the blocks. Therefore, step Sb
In 1, the capacity (size) of the block at that time is set. The block size is irrelevant to one block for eight lines in the line buffer 22, and may be set every storage time or may be a certain fixed value. In this embodiment, this block size is one transfer capacity in the SCSI standard.

Next, in step Sb2, the control unit 26 sets the read position for reading the compressed data from the buffer memory 23 to the storage position in the previous step. This is a measure for making it possible to immediately read the stored compressed data. After that, the control unit 26
In step Sb3, it is determined whether the set block size is smaller than the difference between the storage position and the read position. If the determination result is “No”, it means that the storage position does not precede the read position by the block size, and therefore the read position may overtake the storage position. Therefore, the processing procedure returns to step Sb3 again. As a result, the read position is always 1 more than the storage position.
It will be delayed by more than the block size.

On the other hand, when the result of the determination in step Sb2 is "Yes", the control unit 26 causes the next step Sb.
In 4, the compressed data for one block size is read from the current read position, transferred to the storage unit 25, and stored therein. Then, in step Sb5, the control unit 26 determines whether or not the transfer of the compressed data for the one block size is completed. If this determination result is “No”, in order to perform the transfer completely,
The processing procedure returns to step Sb5 again. Further, when the transfer of the compressed data for the one block size is completed and the determination result in step Sb5 is “Yes”, the control unit 26 in step Sb6.
It is determined whether or not all the compressed data to be read is read. If read, the control unit 26 does not need to perform the following process in this transfer process. Therefore, if the process is not read, the control unit 26 reads compressed data corresponding to the next block. In step Sb7, the read position is shifted by one block size. At this time, the processing procedure is performed again in step S so that the read position does not precede the storage position.
Return to b3.

Then, the control section 26 starts from step Sb3.
As a result of repeatedly executing the process of Sb7, the compressed data stored in the buffer memory 23 is read out and transferred by being delimited for each one block size from a position delayed by one block size or more from the storage position. It will be stored in the storage unit 25. That is, in this embodiment, instead of storing the compressed data for one page in the buffer memory 23 and then starting the transfer to the storage unit 25, if the compressed data for one block size is stored, that portion is immediately stored. 25. Therefore, the buffer memory 23 can exert its function even with a small capacity, and further, the time required for transfer can be shortened.

The storage unit 25 stores one page of compressed data in a plurality of blocks transferred for each block size. Here, in the storage unit 25, block numbers are assigned in the order of transferred blocks, and these blocks are assigned to the control unit 2
6 manages in page units. For example, as shown in FIG. 5, the compressed data corresponding to the original A is a block (1).
Compressed data corresponding to the original B is similarly stored in blocks (5) to (17), and compressed data corresponding to the original C is similarly stored in blocks (17) to (2).
0) are stored respectively. Since the compressed data capacity for one page varies depending on the document size and the like, the number of blocks naturally varies.

On the other hand, when the compressed data stored in this way is read out, by designating a page of a desired document, the blocks corresponding to the page are read out in order of increasing number. . Therefore, the compressed data stored in the storage unit 25 next is stored in the buffer memory 23.
The process up to the transfer to the image compression / decompression unit 22 via the will be described. FIG. 4 is a flowchart showing the process. This step is performed by the buffer memory 2 shown in FIG.
3 is stored in the buffer memory 23, and the image compression / decompression unit 22 is read from the buffer memory 23.
To transfer.

First, the control unit 26 sets the storage position where the read compressed data should be stored in the buffer memory 23 (step Sc1), and sets the block number corresponding to the designated page as the read block number (step S1). S
c2) Further, the read position for reading the compressed data from the buffer memory 23 is shifted to the set storage position (step Sc3).

Next, in step Sc4, the control unit 26 determines whether or not the buffer memory 23 has an area for storing the compressed data of one block size. If the area does not exist, the processing procedure returns to step Sc4 again, and continues to circulate until the area is secured. When the area exists, the determination result of step Sc4 is “Yes”, and the control unit 26 reads the compressed data of the set read block number from the storage unit 25 and outputs the compressed data to the buffer memory in step Sc5. 23, and transfers the transferred compressed data to the buffer memory 23 in the next step Sc6.
Store at the set storage location.

Next, the control unit 26 determines in step Sc7 whether or not the data size when the compressed data stored in the buffer memory 23 is expanded is fixed.
If not decided, the processing procedure will be described in step S below.
On the other hand, if it is determined while skipping to c10, the control unit 26 transfers the determined compressed data to the image compression / expansion unit 22 (step Sc8), and reads the next compressed data stored in the buffer memory. The read position of 23 is shifted (step Sc9).

The control unit 26 then proceeds to step Sc10.
In the above, the transfer of the compressed data from the storage unit 25 to the buffer memory 23, and the buffer memory 2
It is determined whether or not the transfer of the compressed data from 3 to the image compression / expansion unit 22 is completed. If you're done,
Since all the data to be transferred has been transferred, this process ends, while if it has not ended, the processes of the next steps Sc11 and Sc12 are performed. That is, the control unit 26 shifts the storage position of the buffer memory 23 by one block size to store the compressed data belonging to the next block (step Sc11), and reads the compressed data corresponding to the next block. , The read block number is set to the next number (step Sc12). Transfer to the buffer memory 23 cannot be performed unless there is a storage area in the buffer memory 23.
After the processing of, the processing procedure returns to step Sc4.

Then, the control section 26 starts from step Sc4.
As a result of repeatedly executing the process of Sc12, the compressed data stored in the storage unit 25 is stored in the order of block numbers as long as the storage area exists in the buffer memory 23, while the stored compressed data is expanded. Each time the subsequent data size is determined, the data size is transferred to the image compression / expansion unit 22. The compressed data transferred to the image compression / decompression unit 22 is decompressed and decoded into the original image data. After that, the image data is sent to the image output unit 30 in synchronization with the synchronization signal SYNC via the line buffer 21, as described above.
The image output unit 30 forms an image according to the image data.

As described above, according to this embodiment, when the compressed data is read from the storage unit 25 and decompressed, the read speed from the storage unit 25 and the transfer speed to the image output unit 30 are significantly increased. Even when the difference is different from the above, the image formation can be performed based on the expanded image data. Moreover, storage unit 2
At the time of reading from 5, the storage area exists, and of the designated one page of compressed data, which corresponds to the first block, is stored in the buffer memory 23,
Since the transfer from the buffer memory 23 to the image compression / expansion unit 22 is started (step Sc5), it is not necessary to wait for the transfer until all the compressed data for one page is stored in the buffer memory 23, and the transfer waiting time is increased accordingly. It can be shortened.

Since the line buffer 22 in the above-described embodiment is provided mainly for the purpose of converting the format of image data, the format of the data output from the image input unit 10 and the image compression / expansion unit 22 are used. If the required data format matches and the data format expanded by the image compression / expansion unit 22 matches the data format requested by the image output unit 30, it is not necessary to provide it. Further, in the present embodiment, the JPEG method is used as the compression / expansion algorithm, but the present application is not limited to this.

[0036]

As described above, according to the present invention,
It has the following effects. It is not necessary to wait for the transfer until one page of data is stored, and it is possible to transfer when the blocks are completed, so that the transfer waiting time can be shortened (claims 1 and 2). Since the storage and the transfer are performed in parallel, it is possible to reduce the capacity required as the second storage means (claim 3,
4). Even when the already stored data is read out, the capacity required as the second storage means can be reduced and the transfer standby time can be shortened (claims 5 and 6). When the data to be compressed is supplied from the image input means, or when the data after the expansion processing is supplied to the image output means, it is possible to prevent the loss of the image data. . An image can be formed by shortening the transfer standby time and reducing the capacity required as the second storage means (claim 8).

[Brief description of drawings]

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

FIG. 2 is a flowchart showing steps until image data output from an image input unit is stored in a buffer memory in the embodiment.

FIG. 3 is a flowchart showing a process until encoded data stored in a buffer memory is stored in a storage unit in the embodiment.

FIG. 4 is a flowchart showing a process until encoded data stored in a storage unit is transferred to an image compression / decompression unit via a buffer memory in the embodiment.

FIG. 5 is a diagram for explaining a storage state of a storage unit.

[Explanation of symbols]

10 ... Image input section (image input means), 22 ... Image compression / expansion means (compression means, expansion means), 23 ... Buffer memory (second storage means), 25 ... Storage unit (first storage) 26) control unit (writing control unit, read control unit, management unit, parameter setting unit), 30 ... image output unit (image output unit)

Claims (8)

[Claims] 1. The image data read by the image input means is compressed by the compression means and then transferred to and stored in the first storage means having the upper limit of the transfer speed, while the first storage means is stored as necessary. In the image data storage method of arbitrarily reading out the compressed image data from the means, decompressing the image data by the decompressing means, and outputting the image data to the image output means, the image data is compressed in the input order by the compressing means, A second transfer means that the upper limit of the transfer speed is gentler than that of the first storage means.
And a second step of storing the data stored in the second storage means into blocks by arbitrarily dividing the data stored in the first storage means and storing the data in blocks. And a third step of managing the transferred plural blocks of data in page units. 2. The image data read by the image input means is compressed by the compression means and then transferred to and stored in the first storage means having the upper limit of the transfer speed, while the first storage means is stored as necessary. The image data compressed by the means is arbitrarily read out, and after being decompressed by the decompressing means, the image data is output to the image output means in the image data storage device, and the image data is compressed by the compressing means in the order of input. Second storage means for storing the second storage means having a gentler upper limit of transfer rate than the first storage means, and data stored in the second storage means Write control means for dividing the data into blocks and transferring and storing the data in the first storage means for each block, and management means for managing the transferred data of a plurality of blocks in page units. And a storage device for image data. 3. The writing control means transfers a predetermined amount of data to the first storage means as one block each time the amount of data stored in the second storage means reaches a predetermined amount. The image data storage device according to claim 2, wherein the image data storage device stores the image data. 4. The first storage means, the second storage means, the writing control means, or the management means stores, stores, in synchronization with the image input means and the image output means, respectively. The image data storage device according to claim 2 or 3, wherein the image data storage device transfers or manages the image data. 5. A read control means for reading out data of a plurality of blocks forming an image for one designated page from the first storage means in the order in which they are stored and storing the read data in the second storage means. 3. The image according to claim 2, wherein the second storage unit transfers the data of the stored data to the decompression unit each time the data amount of the decompressed data is determined. Data storage device. 6. The first storage means, the second storage means, the writing means, the management means, or the read control means are synchronized with the image input means and the image output means, respectively. The image data storage device according to claim 5, which stores, stores, transfers, manages, or reads. 7. The transfer speed when the image data is output from the image input means, and the compressed image data is the first
Parameter setting means for setting a parameter that determines the compression ratio in the compression means according to the transfer rate of the data transferred to the storage means or the transfer rate of the expanded image data to the image output means. The image data storage device according to claim 2. 8. The image data read by the image input means is compressed by the compression means and then transferred to and stored in the first storage means having the upper limit of the transfer speed, while the first storage means is stored as necessary. The image data compressed by the means is arbitrarily read out, and after being decompressed by the decompressing means, the image data is output to the image output means in the image data storage device, and the image data is compressed by the compressing means in the order of input. Second storage means for storing the second storage means having a gentler upper limit of transfer rate than the first storage means, and data stored in the second storage means Write control means for dividing the data into blocks and transferring and storing the data in the first storage means for each block, and management means for managing the transferred data of a plurality of blocks in page units are designated. Read control means for reading data of a plurality of blocks forming an image for one page from the first storage means in the stored order and storing the read data in the second storage means; The means transfers the stored data to the decompression means each time the data amount when decompressing the stored data is determined, and the image output means forms an image based on the image data decompressed by the decompression means. An image forming apparatus characterized by performing.