JP3387300B2 - Image processing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus having a storage unit for temporarily storing image data, and more particularly to efficient buffer management.

[0002]

2. Description of the Related Art In recent years, in image processing apparatuses such as digital copying machines, printers, facsimiles, and multi-function machines combining these functions, generally, the speed difference between the image input section and the image output section is reduced. In order to absorb, an image storage unit is mounted in the device to some extent. As the image storage unit, a hard disk or a magneto-optical disk that can store a large amount of data at a low price but has a slow write / read speed, and a semiconductor memory that is expensive but has a fast write / read speed are known. .

Image processing apparatuses of recent years use them in combination in order to make the best use of the characteristics of both. By mounting such two types of image storage units, not only the speed difference absorption described above but also various and effective image processing can be realized.
That is, when such two types of image storage units are used together, for example, the function of storing the input image data in the image storage unit and outputting it a plurality of times, the image data in an output order different from the input order It is possible to realize functions that are indispensable for recent image processing apparatuses, such as an electronic sorting function for outputting

On the other hand, a method of compressing image data has become widespread in order to reduce the capacity of the image storage section and to transfer the image data at high speed. By compressing the image data, a large number of pages of images can be stored at one time, and the transfer time such as writing / reading can be shortened, so that high-speed processing becomes possible. However, according to a general variable-length compression process, the compression rate varies depending on the content of image data, so that the amount of data after compression varies for each page.

Therefore, in order to miniaturize and efficiently use a semiconductor memory (hereinafter referred to as a page buffer) capable of storing a plurality of image data, the buffer next to the last address is set to the first address to make the buffer virtual. A device that uses a page buffer (hereinafter referred to as a ring buffer) that is circular in nature is disclosed in, for example, Japanese Patent Laid-Open No. 60-100872. In the system which realizes the above electronic sorting function by using the page buffer and the hard disk while performing the compression process, the ring buffer method can be said to be the most suitable method at present.

However, in the image processing apparatus, the image input order and the image output order are not always the same due to double-sided / single-sided processing, the number of print copies, the operation sequence of the output apparatus, and the like. For example, for an output device capable of double-sided output (for example, a printer), a device that outputs in the order of front, back, front, ..., or a device that outputs in the order of front, front, front, back, back, back, ... Exists. Therefore, even if the input order is adjusted to a specific output device, it is impossible to output to the other output device in the input order. In this way, when the input order and the output order are different, in the above-mentioned ring buffer method that handles compressed images, free areas in the buffer are scattered when areas where compressed images are stored are released in a predetermined order. Will end up.

Since the empty area is an area in which the image data after variable length compression is stored, the size of the area varies, and even if there is an empty area, the next compressed image data is not always present. Can not be stored. That is, the ring buffer is characterized by being able to secure a continuous free area, but due to the difference in the input order and the output order, it cannot exhibit its characteristics. In some cases, the buffer as a whole has a sufficient free area. There is a problem (deadlock) in which the next image data cannot be stored due to the dispersion of each free area,
There was a problem that input processing and output processing could not be performed in parallel.

In this regard, as disclosed in Japanese Patent Laid-Open No. 2-288464, the buffer storage order is changed according to the page output order (descending order), and two-sided output is possible as in Japanese Patent Laid-Open No. 60-74768. In which a buffer is divided and stored in two, one for the front side and the other for the back side, Japanese Patent Laid-Open No. 6-86030
When deadlock occurs in the buffer due to a different order as in Japanese Patent Publication, a page different from the output order (page convenient for releasing the buffer area) is output to avoid the deadlock. Various methods such as things have been proposed.

[0009]

However, the buffer management system as disclosed in Japanese Patent Laid-Open No. 60-74768 described above only supports double-sided output, and output by double-sided / single-sided switching. The change in order and the efficient management of the buffer in the case of outputting a plurality of times are not sufficiently considered.

Further, in the deadlock avoidance method as disclosed in Japanese Patent Laid-Open No. 6-86030, not only the output order different from the output order intended by the user is output, but also the set regular order is set. Job is not processed in
Further, there is a problem that the user has to manually rearrange the image data after outputting the image, which is troublesome.

Further, in the buffer storage method disclosed in Japanese Patent Laid-Open No. 2-288464, since image data is stored in the buffer in the output order, there is no problem of deadlock, but the same image is generated. Since the number of data outputs is not considered, for example, when outputting only specific image data multiple times, the buffer area is released by the first output and the second output is attempted. To read the image data from the hard disk again, as a result,
The processing speed was slow.

In the buffer management method of dividing a block into blocks, which is a known technique, the buffer is cut out in page units even if the input order and the output order are different, but no problem occurs. When handling a long compressed image, a wasteful area is secured, and as a result, there is a problem that the entire buffer must be unnecessarily increased.

The present invention has been made in view of the above conventional problems, and an object thereof is to provide an image processing apparatus in which the order of writing image data to a buffer and the order of reading image data from the buffer are different. It is to solve the problem that the next image data cannot be stored because the free areas are dispersed in the buffer.

Another object of the present invention is to eliminate the above deadlock while minimizing the image data waiting for the free space.

[0015]

(1) To achieve the above object, the present invention provides a storage unit for storing a plurality of image data, a writing unit for writing image data in the storage unit, and a storage unit for storing the image data. comprising reading means for sending to the read output device image data, wherein the writing means, prior to storage in the storage unit of the image data, those
When necessary reading is performed for each image data
And having a release sequence calculation means for calculating the release order of the storage areas each image data is stored, and a write control means for writing the image data to the storage unit in accordance with the release order in.

According to the above construction, the image data is written by the writing means to the storage section constituted by, for example, a buffer, while the stored image data is read by the reading means to output the output device (eg printer). )
Is output to. Prior to writing each image data to the storage unit, the release order calculation means calculates the release order of the storage area for each image data. Then, the writing control unit writes each image data according to the release order.

In a preferred aspect of the present invention, the release order in which the storage area is actually released after each image data is read a required number of times is calculated in advance, and the image data is written according to the release order. Therefore, the free area (empty area) is always generated continuously, and the empty area can be made continuous. In particular, when storing variable-length compressed image data, which will be described later, the data amount of each image data differs depending on the compression degree. But
It is possible to smoothly store the data without putting it in a waiting state for writing. Further, according to the present invention, the next image data can be written from the next address of the previously stored storage area, so that efficient storage can be realized and the above deadlock can be prevented.

(2) In a preferred aspect of the present invention, the reading means reads each image data from the storage unit in a reading order according to the output condition of each image data and the operation condition of the output device. That is, for example, when the present invention is applied to a printing system, printing conditions (double-sided printing / single-sided printing, number of copies, etc.) as output conditions and operating conditions of a printing apparatus (feeding and printing operation sequence) Each image data is read out according to.

(3) In a preferred aspect of the present invention, further, before the writing of the image data in the storage unit, there is provided compression means for performing variable length compression on each image data. The present invention is
Although it is applicable to fixed-length image data, it is particularly effective for variable-length compressed image data.

(4) In a preferred aspect of the present invention, the release order calculation means determines the release order based on the output condition of each image data and the operation condition of the output device. Here, the release order calculation unit calculates the release order based on the calculated output order and the first calculation unit that calculates the output order of each image data while considering the number of output copies of each image data. A second calculation means.

In a preferred aspect of the present invention,
It includes a job content analysis unit that reads output conditions input together with the image data, and a job table that stores the output conditions. The release order calculation unit calculates the release order by referring to the job table.

Here, in a preferred aspect of the present invention, the storage unit is a hard disk or a buffer, and the latter is, for example, a ring buffer in which variable-length compressed image data is stored.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In this embodiment,
A printer device as an image processing device will be described as an example.

FIG. 1 is a schematic diagram showing a configuration example of a system to which the present invention is applied. Various printers 1A-1D
Are print servers 2A to
It is connected to 2D. The print servers 2A to 2D are
The input / output control of image data and the editing of image data are performed. The print servers 2A to 2D are connected to, for example, a local area network 4 (hereinafter, referred to as LAN) on a network set up in a predetermined area, and the LAN
It is connected to the public line 5 or the like via 4 and can communicate with other input / output devices and terminal devices (including the facsimile device 6 etc.) via these nets.

The user uses the graphical user interface (GUI) in the client 3 or a print command provided in an application such as word processing software to print to any of the print servers 2A to 2D on the net. Request (print job). The print server that receives this request outputs the image data to the printer connected to the print server or to another print server while performing the appropriate image processing by checking the content of the job. As a result, the print processing desired by the user is realized.

Direct printing is used for outputting image data to a printer connected to the print server.
The case where image data is output to another printer via another print server is called redirect printing.

FIG. 2 shows various printers 1A shown in FIG.
1 to 1D are cross-sectional views showing an example. The printer 1 shown in FIG. 2 will be described below for reference.

The image forming unit M1 provided inside the printer 1 forms a toner image corresponding to the original image on the recording paper based on the image information transmitted from the terminal device on the LAN 4 or the public line. And this printing unit M2
And a paper feeding unit M3 that supplies recording paper to the paper. Here, the printing unit M2 forms a toner image on a recording sheet by a well-known electrophotographic method in accordance with the digital image data from the processing unit, and the toner image of the photosensitive drum M5 uniformly charged by the charging device M4. The surface is exposed by laser light from the laser exposure device M6 to form an electrostatic latent image. The laser exposure device M6 is a laser element (not shown) such as a semiconductor laser whose drive current is modulated based on image data, and directs laser light from the laser element in a direction orthogonal to the moving direction of the surface of the photosensitive drum M5. It is composed of a rotating polygon mirror M7 that periodically deflects, a reflecting mirror M8, and the like.

The electrostatic latent image on the photoconductor drum M5 is developed by the developing devices M9 and M10 to form a toner image of a desired color on the photoconductor drum M5. This toner image is transferred to the transfer portion M.
By 11, the image is transferred onto the recording paper sent along the path A from any one of the plurality of trays M3a to 3e of the paper feeding unit M3. It should be noted that the trays M3a to 3c are paper feed trays for storing papers of different sizes, the tray M3d is an intermediate tray for temporarily storing recording papers for double-sided copying, and the M3e is for several hundred sheets. It is a large-capacity tray that stores the recording paper of. After the transfer, the residual toner remaining on the surface of the photosensitive drum M5 is removed by the cleaning unit M12.

The recording sheet after transfer is peeled from the photoconductor drum M5 by the peeling section M13, conveyed to the fixing section M15 by the conveyor M14, and subjected to the fixing process. The path of the sheet of paper after fixing is switched by the switching gate M16 to either the path B which goes to the discharging section M17 or the path C which goes to the intermediate tray M3d through the reversing section M18 for double-sided copying. In the case of double-sided copying, the front and back sides of the recording paper are reversed at the reversing unit M18 and are supplied again to the printing unit M2 along the path A via the intermediate tray M3d, and a toner image is formed on the back surface of the recording paper this time. After that, it is sent to the discharge unit M17.

FIG. 3 is a diagram showing an embodiment of the image processing apparatus according to the present invention, and is specifically a hardware block diagram in the print server 2. The print server 2 includes an image forming unit (Image Output Terminal: IOT) 1
10 (corresponding to the printer 1 shown in FIG. 1) is connected, and a network interface (Ether I / F) 101
The LAN 4 is connected via. In the present embodiment, Ethernet is shown as an example of LAN.

The print server 2 has the above-mentioned network interface 101, a compressor (Compressor) 102 for compressing image data, and a D for transferring image data.
MA (Direct Memory Access) controller 103, CPU 104 for performing software processing, RAM / R
CPU peripheral chips such as OM / clock generator (Peri
pheral) 105, a page buffer (ring buffer) 106 for storing image data, a hard disk 108 (HD) for temporarily storing image data,
A disk controller (Disk Cont) 107 for controlling a hard disk, a decompressor 109 for decompressing image data, an internal bus 111 for transferring image data and control data, and the like are included.

Next, the overall operation of the print server 2 will be described. Image information from the network is usually Page Description Language (PDL).
However, since the image information handled by the IOT 110 is raster data (bitmap data), it cannot be output to the IOT 110 as it is. Therefore, when image information is input from the LAN 4, it is necessary to first convert the image information into raster data. This processing is called decomposing, and the module (software or hardware) that performs the decomposing processing is called a decomposer. The image data that has undergone the decomposing process and has been converted into raster data is compressed by the compressor 102 and temporarily stored in the page buffer 106. Since the page buffer 106 has a small capacity, the image data is transferred to the hard disk 108 and temporarily saved.

On the other hand, the compressed image data is I
When outputting to the OT 110, the image data is transferred to the decompressor 109 through writing / reading to the page buffer 106 as described later in detail, and the decompressed image data is output to the IOT 110. IOT
In 110, in the image forming unit M1 shown in FIG. 2, halftone dots are formed by controlling on / off of laser light for each pixel based on the binary data generated from the input image data. The halftone image is reproduced, and the print image is output.

The image data is output by such a series of processes. The process of decomposing the image information, the process of storing the compressed image data in the page buffer 106 while performing the compression process, the temporary saving to the hard disk 108 or the hard disk. To page buffer 106
The process of returning the image data to the IOT 110 and the process of outputting the image data from the page buffer 106 to the IOT 110 while decompressing the image data are processed in parallel by the bus arbitration and the time division process of the internal bus 111 as much as possible. As a result, the processing speed can be improved as a result.

FIG. 4 is a functional block diagram showing the control unit 10 of the print server 2. Also,
FIG. 5 shows a job management table used in controlling the control unit 10.

From a hardware perspective, the control unit 10 of FIG. 4 is, for example, C as shown by reference numeral 10 in FIG.
It is realized by the PU 104, the CPU peripheral chip group 105, and the like. Incidentally, the ROM included in the CPU peripheral chip group 105 stores a control program or the like for causing the CPU 104 to function as a control unit, and the RAM included in the CPU peripheral chip group 105 is formed with a job management table described later. It For convenience of description, FIG. 4 also shows configurations corresponding to the compressor 102, the disk controller 107, and the like.

In FIG. 4, the control unit 10 includes a job receiving unit 201 and a job scheduling unit 203,
Among them, the job queuing unit 202 acts as an intermediary for exchange for job processing. When the job receiving unit 201 receives a job processing request from a client via the net, the job content is analyzed there, and the analysis result is stored in the job ticket table 14 by the job content storage unit 210 (see FIG. 5).
As a result, the job queuing unit 202 performs queuing, while the processing of the job receiving unit 201 waits for the next job.

The job scheduling unit 203 constantly monitors whether or not a job exists in the job queue 12 (see FIG. 5) of the job queuing unit 202, and if there is, the request fetching unit 211 causes the job queue 12 to operate.
Take the job from and check its contents. When it is determined that the job can be processed, the release order calculation unit 2
The processing moves to 12, and the order of releasing the area storing the image data from the buffer is determined by referring to the job content. That is, for example, various parameters (front / back surface type, number of prints, etc.) of each image data (plate) are referred to, and based on this, the release order from the buffer, in other words, the image data is erased from the buffer. The order to do is determined. This release order is stored in the job ticket table 14 for each job (see FIG. 5).

The release order matches the output order when a part of each image data is output, but at least 1
If multiple outputs are made for one image data, the output order does not match. The plate corresponds to an image when printing in black and white. In the case of color printing, this corresponds to an image for each color on each side, and the present invention can be similarly applied.

After the release order is determined, the image generation / compression / writing unit 213 performs the above-described processing for outputting the image data. As is clear from the above, the writing of the image data is performed in the release order calculated by the release order calculation unit 212. The page buffer management unit 214 collectively manages information necessary for managing the image data in the page buffer, such as an empty area, a stored image data number (Plate No.), and an address to be written next.

The job scheduling unit 203 gives an instruction to the image reading unit 215 via the page buffer management unit 214 when preparation for output is completed. As a result, after the image data is written from the hard disk to the page buffer in the release order, the output processing control unit 216
The image data is read from the page buffer in a predetermined order and output processing is performed. As is clear from the above, the page buffer management unit 214 and the image reading unit 2
15 functions as a writing unit, while the output processing control unit 216 and the image reading unit 215 function as a reading unit. The connections between the above modules will be clarified by the flowcharts shown in FIGS.

Next, the page buffer management system according to the present invention will be specifically described.

FIG. 6 illustrates the contents of the job 16 as a table. When a job is input, its contents are analyzed, and the analysis result is tabulated as shown in FIG. Here, the job 16 is the image data of 8 sheets (Plate
), A paper (sheet) number (Page No.), double-sided printing / single-sided printing, and the number of copies are associated with each image data. Here, the specific contents of the job 16 will be described. This job 16 indicates that images for 8 plates should be printed on both sides of three sheets and one side of two sheets. Two copies are required for the third and fourth sheets.

The release order calculation unit 212 determines the release order based on such job contents (processing conditions) and operation conditions (operation sequence) of the output device (IOT). Here, as an output device, for example, when performing double-sided printing, it is assumed that the output device has an operation condition of printing the back surface first and then the front surface in units of three pages at the maximum.

The release order calculation section 212 is roughly divided into two functions, that is, a first order for calculating the output order for each output count.
It has a calculation function and a function of calculating the release order based on the output order for each output count, and its operation is shown as a flowchart in FIG. 7.

In FIG. 7, first, in S101, n is set to 1 as an initial value. This n corresponds to the number of output times such as the first copy and the second copy. S102
Then, all the plates of the nth copy are referred to, and the output rank is calculated for each plate of the nth copy based on the job content and the operating conditions of the output device. FIG. 6 shows the output order for each plate of the first and second copies. In this example, since the output device has the operation condition of printing every three sheets as described above, when performing double-sided printing,
Since there is an operation condition of printing the back side first, a series of output orders as shown in FIG. 6 is set.

In FIG. 7, in S103, it is determined whether or not the output of the (n + 1) th copy is set in at least one plate.
Is incremented, and the output rank is similarly calculated for the next nth copy in S102. In the case of No in S103, the representative ranking is determined for each plate in S105. Specifically, for each plate, the largest output rank given is selected, and this is the representative rank. For example, with respect to the plate 1, 11 is determined as the representative order, and for the plate 3, the plate 5 is determined as the representative order. In S106, the release order is determined in the ascending order of the representative order of the plates thus determined. That is, this release order is an order in which the area where each plate is stored can be overwritten. When writing to the page buffer and reading from the page buffer based on such a release order progress alternately, the area is continuously released, and efficient writing of image data can be realized.

FIG. 8A schematically shows a state (conventional example) in which writing is simply performed in the order of plate numbers and reading is performed in a predetermined reading order. Now
Even if an attempt is made to write the next plate 20 in the write waiting state to the page buffer 106, the page buffer 10
In No. 6, the empty areas 22 to 32 are dispersed, and writing on the plate 20 cannot be performed. Therefore, the write waiting time increases, and deadlock occurs in some cases. On the other hand, according to the present invention, as shown in FIG. 8B, the empty areas are continuous (reference numerals 34 and 36).
), The plate 20 having a relatively low compression rate,
Writing can be smoothly performed using such continuous free areas, and as a result, the write waiting time can be shortened and deadlock can be prevented.

FIG. 9 shows an example of buffer management when writing to the job shown in FIG. 6 in the release order, and FIG. 10 shows buffer management when writing in the input order as Comparative Example 1. An example is shown, and FIG. 11 shows a comparative example 2.
As an example, a buffer management example in the case of writing in the output order is shown. It should be noted that FIGS. 9 to 11 show an example of buffer management in the case where the image data has a fixed length for simplification of description.

As can be seen from FIG. 9, in the buffer management according to the present invention, the image data is written and read in consideration of the number of times of reading required for each image data, so that efficient write and read control is performed. Can be realized. That is, according to the method of the present invention, after the image data is full in the page buffer 106,
The number of times of writing from the hard disk to the buffer, that is, the number of times of overwriting is 2 (writing 5 and writing 7 in the figure), whereas it is 4 times in Comparative Example 1 and 5 times in Comparative Example 2, and the completion time Can be shortened.

Normally, the read speed from the hard disk is slower than the output speed, and if the number of times of writing to the buffer increases, the data processing speed significantly decreases. In particular,
Since the image data having a very low compression rate such as a photographic image has a large data amount, the problem becomes remarkable. According to the present invention, there is an advantage that the processing speed can be improved even in such a case.

The examples of FIGS. 9 to 11 are faithful to the ring buffer method in which the image data is written from the beginning of the buffer without fail and when the end address is reached, the data is returned to the beginning and stored. is there. As shown in Comparative Example 1 and Comparative Example 2, when the method of storing from an empty area early is applied, the probability of obtaining a large continuous empty area is reduced, and thus when the image compression rate is low, Even if there are sufficient free areas in the buffer as a whole, the free areas are dispersed, and it is not possible to store an image with a low compression rate, which often causes cases. If this phenomenon is further aggravated, for example, in an image processing apparatus that outputs a plurality of pages of image data after they are gathered in a page buffer, a large number of small empty areas are scattered discontinuously, so It is impossible to arrange them, and a deadlock occurs (processing is stopped after waiting all the time). According to the present invention, as described above, since writing is performed in the release order, empty areas are continuously formed, and such a problem can be effectively prevented.

Next, the operation of the image processing apparatus of this embodiment will be described with reference to FIGS.

FIG. 12 shows the job acceptance section 20 shown in FIG.
3 is a flowchart showing the operation of No. 1. First, in S1, it is determined whether or not there is a job processing request from the client. When the job processing request is determined, the job content is confirmed in S2, and if processing is possible, the job content is stored in the job management table (job ticket 14). To be done. Then, in S3, the job ticket 14 is queued,
In S4, the job scheduling unit 203 is notified that there is a job request, and the process returns to S1 to wait for the next job request.

FIG. 13 is a flow chart showing the operation of the job scheduling unit 203 shown in FIG.

In S5, when the notification from the job receiving unit 201 is received, the job ticket 14 is transferred from the job queue 12
Take out. Then, in S6, the job contents are checked to see if the information necessary for calculating the release order is given. In S7, the output order and the release order are determined according to the above-described calculation procedure, and the result is stored in the "buffer storage order" area in the job ticket shown in FIG. In S8, the image data is processed so that it can be output. Details of this process are shown in FIG. S
At 9, in order to output the image data, the image data is written in the page buffer. Details of the processing in this case are shown in FIG.

In S10, it is checked whether the above S8 and S9 are ready and output is possible. If not possible, the process proceeds to S11, and if possible, S12 is executed. In S11, it is checked which of the processes in S8 and S9 is not ready, and the process is returned to S8 or S9. Then, in S12, the output process of the image data is executed.
In S13, it is checked whether or not the output of all the image data is completed, and if not, the process returns to S10, and if all the output is completed, the process proceeds to S14. In this S14,
The image data on the hard disk is deleted. In S15, the job ending process is performed, and specifically, the job ticket is deleted.

Note that S16 represents a module that performs output processing by starting the output processing in S12.
It operates in parallel with the main processing (operations shown in FIGS. 12 to 15). The content of the output process is as described based on FIGS. 2 and 3.

FIG. 14 shows the operation of the image processing apparatus corresponding to S8 shown in FIG.

First, the decomposer is activated in S21, and the decompose process is executed in S22. This process is similar to the output process of S16, and is the main process (see FIG.
The operation shown in 15) can be performed in parallel. Since the image information sent from the client is in the page description language, raster data is generated here by decomposing.

At S23, an area for storing the decomposing result is requested on the page buffer. In this case, S24
If it is determined that the area can be secured, the process proceeds to S26.
If not possible, the process proceeds to S25.

At S25, the system waits for a free area, and S
At 26, the process waits for raster data to be stored in the page buffer at S22. Then, in S27, the stored raster data is compressed. In S28, the process of writing the compressed image data that has been compressed to the hard disk is started. The process of writing to the hard disk in S29 is executed in parallel with the main process (operations of FIGS. 12 to 15), like the decomposing process of S22 and the output process of S16.

At S30, when the process of writing to the hard disk is completed, the page buffer can be overwritten, so the buffer management table is updated. On the other hand, S3
In the case of 1, in the case of waiting for the buffer to be vacant in S25, it is checked in S24 whether it can be secured again based on the update result. In S32, it is checked whether or not the writing process has been completed for all the plates. If not, the process returns to S21 to repeat the process, and if completed, the flow exits.

FIG. 15 shows the operation of the image processing apparatus corresponding to S9 shown in FIG.

In S41, the process of reading the compressed image data from the hard disk is started based on the "buffer storage order" (release order) information set in S7. Here, the process of reading from the hard disk in S42 is
Similar to the writing process of S29, the main process (see FIGS.
(Operation shown in 5)). In S43, an area for storing the read result is requested on the page buffer.

In S44, if the area can be secured, the process proceeds to S46, and if not, the process proceeds to S45. In S45, a free space waiting state is entered. In S46, the process waits for the compressed image data to be read onto the buffer in S42.

S47 is a module for performing the output process shown in S16. Every time the output of one page is completed, the fact is notified. In S48, the buffer management table is updated based on the information indicating the end of output of one page. In S49, when waiting for the buffer to be free in S45, it is determined whether or not the buffer can be secured again based on the update result.
Check at 4. Then, in S50, it is checked whether or not all the outputs are completed, and if not, S4.
When the process returns to 1 and the process is repeated, and the process ends, this flow ends.

Note that, in actual input / output control of image data, error cancellation processing, communication processing, and the like exist in addition to the above, but they are omitted because they are not related to the present invention. Further, in the above embodiment, the printer is taken as an example, but if the image processing apparatus has a buffer,
The present invention can be applied to any image processing device such as a copying machine, a printer device, a facsimile device, and the like.

[0070]

As described above, according to the present invention,
In an image processing device in which the order of writing image data to the buffer and the order of reading image data from the buffer are different, it is possible to solve the problem that the empty area is dispersed in the buffer and the next image data cannot be stored. Also, deadlock can be effectively prevented while minimizing the amount of image data waiting for a free space.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a system configuration to which the present invention is applied.

FIG. 2 is a sectional view showing a schematic configuration of a printer to which the present invention is applied.

FIG. 3 is a hardware block diagram showing an embodiment of an image processing apparatus according to the present invention.

FIG. 4 is a diagram showing a configuration of a control unit according to the present invention.

FIG. 5 is a diagram showing a management table.

FIG. 6 is a diagram showing the contents of a job.

FIG. 7 is a flowchart showing a method of calculating a release order.

FIG. 8 is an explanatory diagram comparing a conventional example with the present invention.

FIG. 9 is a diagram showing buffer write control according to the present invention.

FIG. 10 is a diagram showing a first comparative example in which writing is performed in input order.

FIG. 11 is a diagram showing a comparative example 2 in which writing is performed in output order.

FIG. 12 is a flowchart illustrating a control procedure according to the present invention.

FIG. 13 is a flowchart illustrating a control procedure according to the present invention.

FIG. 14 is a flowchart illustrating a control procedure according to the present invention.

FIG. 15 is a flowchart illustrating a control procedure according to the present invention.

[Explanation of symbols]

1A-1C printer, 2A-2D print server,
102 compressor, 109 decompressor, 106 page buffer, 201 job receiving unit, 202 job queuing unit, 203 job scheduling unit, 212
Release order calculation unit, 214 page buffer management unit.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 1/21 G06F 3/12 G06T 1/00 G06F 12/00

Claims (7)

(57) [Claims] 1. A storage unit for storing a plurality of image data, a writing unit for writing the image data to the storage unit, and a reading unit for reading the image data from the storage unit and sending the image data to an output device. writing means, prior to storage in the storage unit of the image data, the respective
When necessary reading of image data is performed
The image is characterized by comprising: a release order calculation means for calculating a release order of a storage area in which each of the image data is stored; and a write control means for writing the image data to the storage section according to the release order. Processing equipment. 2. The apparatus according to claim 1, wherein the reading unit reads each image data from the storage unit in a reading order according to an output condition of each image data and an operation condition of the output device. Image processing device. 3. The image processing apparatus according to claim 1, further comprising a compression unit that compresses each image data in a variable length prior to writing the image data in the storage unit. 4. The image processing apparatus according to claim 1, wherein the release order calculation unit determines the release order based on an output condition of each image data and an operation condition of the output device. 5. The apparatus according to claim 4, wherein the release order calculation unit calculates the output order of each image data while considering the number of output copies of each image data, and the calculated output. An image processing apparatus comprising: a second calculation unit that calculates the release order based on the order. 6. The apparatus according to claim 1, further comprising: a job content analysis unit that reads an output condition that is input together with the image data; and a job table that stores the output condition. An image processing apparatus, wherein the output order is calculated with reference to the job table. 7. The image processing apparatus according to claim 1, wherein the storage unit is a ring buffer in which variable-length compressed image data is stored.