JP2002010088A - Image processor, image processing method and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable compression of image data in such a manner that the size of image data after compression is just sufficient to a locative region for locating the image data after compression, and image quality is damaged as little as possible. SOLUTION: When the size of a compressed image locative region 223 is smaller than the image data (S3002), an initial compression parameter is determined (S3004) from the ratio of the image data to the size of the locative region 223, and the image data are compressed (S3005) according to the initial compression parameter. The size of a compressed image block is counted (S3006). In the case of compression failure (S3010), the compression parameter is updated (S3011) on the basis of the size of original image data and the size of compressed image data for one page. The compression parameter is updated (S3013), corresponding to also a superfluous region in the locative region 223.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image processing apparatus, an image processing method, and a storage medium for compressing image data and storing the compressed image data in a predetermined storage means.

[0002]

2. Description of the Related Art There are various methods of compressing image data, and one of them is used in actual compression processing. The compression processing is basically performed according to the set compression parameters. If the storage area of the compressed image data becomes insufficient during the compression processing, the compression processing is stopped. Then, the compression parameter is changed by a fixed amount, the compression ratio is increased, and compression is attempted again. As described above, in the related art, when the compressed image data does not fit in the storage area of the image data, the operation of changing the compression process or changing the compression parameter by a certain amount is repeated until the image data becomes smaller.

[0003]

In the conventional image data compression processing, when the size of the compressed image data exceeds the size of the storage area, the compression processing is stopped and the compression parameter is changed. However, the amount of change in the compression parameter was always constant. Therefore, depending on the image data, the compression process and the change of the compression parameter may be repeatedly and repeatedly performed until the compressed image data fits in the storage area.

With a compression parameter that changes by a fixed amount, it is conceivable that the image data after compression becomes smaller than the storage area and the storage area is largely left behind. This means that the original image data is compressed more than necessary. In the case of irreversible compression, the image quality is wasted and high image quality cannot be expected.

[0005] The reason why the compressed image data is significantly larger or smaller than the storage area is that the optimal compression parameter has not been set or the compression method has not been properly set.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and the size of compressed image data is sufficient for a storage area for storing the compressed image data, and the image quality is not impaired as much as possible. The object of the present invention is to control the compression of the image data.

[0007]

In order to achieve the object of the present invention, for example, an image processing apparatus of the present invention has the following arrangement. That is, the image data is compressed,
What is claimed is: 1. An image processing apparatus for storing compressed image data in a predetermined storage unit, comprising: setting a compression parameter estimated to give a size that can be stored in the predetermined storage unit when the image data is compressed. Means, a calculating means for calculating a compression ratio when the image data is compressed using the compression parameter, and a size of the compressed image data is larger than a size of a storage area of the predetermined storage means. When the compression parameter is large, the compression ratio estimated by the compression parameter and the compression ratio by the calculation unit are provided with a change unit that changes the compression parameter according to the compression ratio, and the compression parameter changed by the change unit is used. Then, the image data is compressed again.

[0008] Further, when the size of the compressed image data is smaller than the size of the storage area of the predetermined storage means, the changing means determines the size of the storage area of the predetermined storage means and the size of the compressed image data. The compression parameter is changed according to the difference from the data size.

[0009] Furthermore, a plurality of compression methods and condition information for selecting each compression method are provided, and when a condition described in the condition information is satisfied, the plurality of compression methods correspond to the condition information. The image processing apparatus further includes a selection unit that selects a compression method, and performs compression on the image data again using the compression method selected by the selection unit and a compression parameter used for the compression method.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image processing apparatus according to the present invention is applied to a laser beam printer (hereinafter abbreviated as LBP), and the present invention will be described in detail according to preferred embodiments with reference to the accompanying drawings.

[First Embodiment] An LBP as an image processing apparatus according to the present embodiment will be described with reference to FIG.

FIG. 1 is a sectional view showing the internal structure of the aforementioned LBP.

In FIG. 1, reference numeral 100 denotes an LBP main body, which is a host computer (20 in FIG. 2) connected to the outside.
Character print command, various graphic drawing commands supplied from 1),
A corresponding character pattern, figure, image, or the like is created in accordance with an image drawing command, a color designation command, and the like, and an image is formed on a recording sheet as a recording medium.

Reference numeral 151 denotes an operation panel on which an operation switch and an LED display and an LCD display for displaying the status of the printer are arranged. 101 denotes a control of the entire LBP 100 and a character printing command supplied from the host computer 201. And a printer control unit for analyzing the data.

Note that the LBP in the present embodiment converts RGB color information into M (magenta) C (cyan) Y (yellow) K
Each of MCYKs has an image forming / developing mechanism to convert them into (black) images and develop and develop them in parallel. The printer control unit 101 generates a print image of each of MCYK, converts the print image into a video signal, and outputs the laser driver (110, 120, 130, 14) of each of MCYK.
0).

M (magenta) laser driver 110
Is a circuit for driving the semiconductor laser 111,
The laser beam 112 emitted from the semiconductor laser 111 is turned on / off according to a video signal input from the printer control unit 101. The laser beam 112 is swung right and left by a rotary polygon mirror 113 to scan on an electrostatic drum 114. As a result, an electrostatic latent image of a character or graphic pattern is formed on the electrostatic drum 114. This latent image is developed by a developing unit (toner cartridge) 115 around the electrostatic drum 114 and then transferred to a recording sheet.

C (cyan), Y (yellow), and K (black) have the same image forming and developing mechanism as M (magenta), and have 120, 121, 122, 123, 124,
125, an image forming / developing mechanism for C (cyan);
131, 132, 133, 134, 135 are image forming / developing mechanisms for Y (yellow), 140, 141, 142,
Reference numerals 143, 144, and 145 denote image forming / developing mechanisms for K (black). The individual functions are the same as those of the M (magenta) image forming / developing mechanism, and the description is omitted.

A cut sheet is used as a recording sheet, and the cut sheet recording sheet is a sheet cassette 1 mounted on the LBP 100.
02, which is held at a fixed height by a spring 103, is taken into the apparatus of the LBP 100 by a paper feed roller 104 and transport rollers 105 and 106, and is placed on a paper transport belt 107 to form each image of MCYK. It passes through the forming / developing mechanism.

Each toner (powder ink) of MCYK transferred to the recording paper is fixed to the recording paper by heat and pressure in a fixing device 108, and the recording paper is output to the upper part of the LBP 100 by conveying rollers 109 and 150.

FIG. 2 is a block diagram showing a schematic configuration of the printer control unit 101 of the LBP 100 shown in FIG.

The printer control unit 101 inputs data 214 including characters, graphics, image drawing commands, color information, and the like sent from the host computer 201, which is a source of print information. Document information and the like are printed. An input / output interface unit 202 exchanges various information with the host computer 201, and an input buffer memory 203 temporarily stores various information input from the host computer 201 via the input / output interface unit 202. Reference numeral 204 denotes a character pattern generator, which includes a font information section 218 storing attributes such as the width and height of the character and the address of the actual character pattern, and a character pattern section 219 storing the character pattern itself. The character pattern reading control program is stored in the ROM 215, and has a code conversion function of calculating a character pattern address corresponding to the character code when the character code is input.

Reference numeral 205 denotes a RAM, which is a character pattern generator 2
A font cache area 207 for storing a character pattern output from the host computer 04, a storage area 206 for storing external character fonts and form information sent from the host computer 201, a current printing environment, and the like. By storing the pattern information once expanded into the character pattern in the font cache area 207 as the font cache in this manner, when printing the same character, it is not necessary to decode the same character again and develop the pattern. Expansion into minute character patterns is faster.

Reference numeral 208 denotes a CPU for controlling the entire control system of the LBP 100, and a CPU 208 stored in the ROM 215.
The control program 208 controls the entire LBP 100. An intermediate buffer 209 stores intermediate data, which is an internal data group generated based on the input data 214.

When the reception of one page of data from the host computer 201 has been completed,
The received data for one page is converted into intermediate data and stored in the intermediate buffer 209, then rendered by the renderer 210 based on the intermediate data, and output to the image buffer 211 as a print image.

The image buffer 211 is a renderer 210
Can be stored as dot data for one page. The compressor 222 is a part for compressing an image. When a print image for one page is output to the image buffer 211, the compressor 222 compresses the image and outputs it to the compressed image storage area 223. The compressed image storage area 223 is a buffer smaller in size than the image buffer 211, and the compressed print image data output here is copied to the hard disk 220 as it is.

The hard disk 220 can record arbitrary information and does not lose information even when the power is turned off. When the same print image is repeatedly used by storing the print image after compression in the hard disk 220, the hard disk 220 may be referred to. Even when a certain page is being output, subsequent pages can be stored in the hard disk 220 one after another, so that the overall processing efficiency can be improved.

In addition to storing the compressed print image, the hard icer 220 also stores the print image in the host computer 20 via the hard disk interface unit 221.
1 for storing print data transmitted from
When the shortage of the capacity 09 occurs, the intermediate data being generated is expanded into image data and used as a work area for compression.

The print image stored in the hard disk 220 is decompressed by an RGB to MCYK converter 224, converted from an RGB color space to an MCYK color space, and passed to an output image interface unit 212 described later. The print image converted into MCYK is further output to the output image interface unit 212.
Is converted into a video signal and output to the printer unit 213. The printer unit 213 is a page for printing image information based on the video signal from the output interface unit 212.
This is the printing mechanism of the printer.

As described above with reference to FIG. 1, since the LBP 100 in this embodiment performs MCYK image formation and development in parallel, the output interface unit 212 includes an M output interface unit, a C output interface unit, and a Y output unit.
An output interface unit and a K output interface unit are configured of four interface units, each of which independently reads dot data from the image buffer 211,
Convert to video signal and laser driver 1 for each plane
Output to 10, 120, 130, 140.

Reference numeral 216 denotes a non-volatile memory constituted by a general EEPROM or the like.
RAM). The NVRAM 216 stores panel setting values specified on the operation panel 151 and the like.

Reference numeral 217 denotes data transmitted from the LBP 100 to the host computer 201.

The ROM 215 stores analysis of data input from the host computer 201, generation of intermediate data, a printer unit (a control program for the printing mechanism main unit 9213, and the like).

Next, the procedure of image data compression processing in the present embodiment will be described with reference to the flowchart of FIG. Note that the program code according to the flowchart shown in FIG. 3 is stored in the ROM 215, read by the CPU 208, and executed using a part of the memory space of the RAM 205 as a work area.

In step S3001, the renderer 210
One page of intermediate data is read from the intermediate buffer 209 and developed into image data (dot data), which is used as original image data in the image buffer 2.
11 is output.

Next, in step S3002, the compressor 222 compares the size of the image data output to the image buffer 211 with the size of the compressed image storage area 223 for storing the compressed image data. If the size of the compressed image storage area 223 is larger than the size of the image data, there is no need for compression, and the process advances to step S3003, and the image buffer 211
Is directly copied to the compressed image storage area 223. However, if the size of the compressed image storage area 223 is smaller than the size of the image data, the size of the image data stored in the image buffer 211 is changed to the size of the compressed image storage area 223.
Must be compressed to a size that can be stored in
Proceed to step S3004.

In step S3004, initial compression parameters are set in preparation for compression of image data. It is assumed that the compression parameter takes a value from 0 to 100. When the compression parameter is 100, there is no loss of image information of the image data at the time of compression, and the loss of image information increases as the compression parameter decreases. In other words, as the compression parameter is larger, higher quality compressed image data can be obtained but higher compression cannot be expected. Conversely, as the compression parameter is smaller, higher compression can be applied to the image data, but higher image quality cannot be expected. For example, in JPEG compression, the Q factor corresponds to this compression parameter.

Next, the details of the method for setting the initial compression parameter will be described. The table shown in FIG. 4 is an example in which, when image data is compressed by a certain compression method, an average image data compression ratio can be obtained for each compression parameter. The left part of the table shows the compression parameter values used when compressing the image data, and the right part shows the percentage of the size of the compressed image data with respect to the original image data when compressed with each compression parameter value. I have. In the compression method shown in the table of FIG. 4, for example, when the compression processing is performed with the compression parameter 90, the size of the image data after compression becomes 91.8% of the size before compression. The table data indicating the correspondence between the compression parameter value and the average compression ratio shown in FIG. 4 is stored in the ROM 215.

In step S3004, an initial compression parameter is tentatively determined from the ratio between the original image data and the size of the compressed image storage area 223. In the present embodiment, the table shown in FIG. 4 is referred to when determining the compression parameter.

First, when the size of the original image data is m and the size of the compressed image storage area 223 is n, the ratio is n / m. Therefore, the maximum value of n / m or less is searched from the column of "average compression ratio (%)" shown in the table of FIG. 4, and the corresponding compression parameter is set as the initial compression parameter. For example, the size of the original image data is 1000 bytes, and the compressed image storage area 223
Is 800 bytes, the ratio is 800/1000 =
80%. If the compression process surely promises a compression rate of 80%, selecting a compression parameter value that can expect the compression rate allows the compressed image data to be stored in the compressed image storage area 223. .

In FIG. 4, the maximum value of the "average compression ratio (%)" of 80% or less is 79.5, and the "compression parameter value" for which this percentage can be expected is 72. Therefore, in this case, the compression parameter value 72 becomes the initial compression parameter.

In step S3005, the previous steps (step S3004, step S3011, step S3
013), one block of image data (one block when the image data is divided into blocks) is compressed. In this embodiment, one block of the compressed data thus created is stored in the compressed image storage area 223 as needed.
This will be described with reference to 3009.

In step S3006, in step S30
The size of the compressed image data for one block output in 05 is acquired and added to the total value of the sizes of the compressed image blocks compressed so far. Of course, when the process of step S3006 is executed for the first time, the above-described total value = 1 compressed image data for one block. Here, the size of the compressed image data for one block is counted regardless of whether the size is stored in the compressed image storage area 223. As a result, even if the compressed image data for one page cannot be finally stored in the compressed image storage area 223, the size of the compressed image data for one page as the compression result can be obtained.

In step S3007, the size of the compressed image data output so far is compared with the size of the compressed image storage area 223. That is, it is determined whether or not one block of image data compressed in step S3005 can be stored in the compressed image storage area 223. If the size of the compressed image storage area 223 is larger than the size of the compressed image data,
The process advances to step S3008 to store the output compressed image data in the storage area. That is, the compressed image data of one block compressed in step S3005 is stored in the compressed image storage area 223. On the other hand, if the size of the compressed image storage area 223 is smaller than the size of the compressed image data, step S3
Since the image data of one block compressed in 005 cannot be stored in the compressed image storage area 23 any more, the process proceeds to step S3009 without doing anything.

In step S3008, the compressed image data is stored in the compressed image storage area 223, and the flow advances to step S3009.

In step S3009, it is checked whether the compression processing for one page of image data has been completed. If the compression process for one page is completed, step S
Proceed to 3010. If not, the process returns to step S3005 to compress the remaining blocks.

The above steps S3005 to S3
What is important between the loops 009 is that the compression processing is not stopped even if the area for storing the compressed image data is insufficient during the compression processing. As a result, the count of each block of the compressed data of one block in step S3006 is utilized, and when the compression processing of one page of the image data is completed, the size after the compression (1
(The size of the compressed image data of the page). In other words, when compression is performed using the compression parameter used at that time, it is necessary to have a size enough to count as a storage area for the compressed image data.

In step S3010, the size of the obtained compressed image data and the compressed image storage area 22
Compare with size 3. Compressed image storage area 223
Is smaller than the size of the compressed image data, the compression has failed, and the process advances to step S3011 to set the compression parameter again. If the size of the compressed image storage area 223 is larger than the size of the compressed image data, the process advances to step S3012.

First, if the compression has failed in step S3010, the following procedure will be described. If the compression has failed, it is necessary to reset the compression parameters so that the compressed image data will fit in the compressed image storage area 223 in the next compression process to increase the compression ratio.

In step S3011, the compression parameters used in the next compression processing are determined by comparing the size of the original image data before compression with the size of the original image data from step S3005 to step S30.
09 is determined based on the size of the compressed image data for one page obtained in step S09.

First, since the sizes of the image data before and after compression are clear, it is possible to know the actual compression ratio of the compression processing performed up to step S1010. Then, a point indicates how far the compression ratio is from the originally desired compression ratio, and the initial compression parameter is increased or decreased according to the point, and the compression parameter in the next compression is determined. FIG. 5 is a table showing an example in which this point and the amount of increase or decrease of the compression parameter corresponding thereto are set arbitrarily. The table data of the correspondence between the points shown in this table and the increase / decrease value of the compression parameter is stored in the ROM 215.

As in the case of step S3004, this is an example of compression processing in which the original image data is 1000 bytes and the compressed image storage area 223 is 800 bytes.
The procedure for determining the compression parameter in step S3011 will be described.

First, if the original image data is 1000
Since the byte and the compressed image storage area 223 are 800 bytes, the desired compression ratio is 80%. Therefore, step S
In step 3004, 72 is set as the initial compression parameter in expectation of a compression ratio of 79.5% according to the table of FIG. Step S3
From 005, actual compression is performed in step S3009,
As a result, it is assumed that the size of the compressed image data is 850 bytes. Since the size of the compressed image storage area 223 (800 bytes) <the size of the compressed image data (850 bytes) in step S3010, the process advances to step S3011. Here, the original image data is 1000 bytes, and the compressed image data is 85 bytes.
The 0 byte means that the actual compression rate of the compression performed in steps S3005 to S3009 was 85%, which exceeds the desired compression rate of 80% by 5 points. In the table, +
Means 5 points. In the table of FIG. 5, the increase / decrease value of the compression parameter corresponding to the (+5) point is (−6). Therefore, the compression parameter used for the next compression process is 72−6 = 6.
It becomes 6. When a new compression parameter is set, the process proceeds to step S3005, and the compression process is started again using the compression parameter with the initial value set to 66.

In this way, although depending on how the table shown in FIG. 5 is created, the optimum compression parameter can be obtained faster than at least a method of changing the compression parameter by a fixed amount each time.

Next, in step S3010, the procedure in the case where the compressed image data is sufficiently stored in the compressed image storage area 223 will be described. In this case, the process proceeds to step S3012.

In step S3012, when the compressed image data is stored in the compressed image storage area 223, it is checked how much space is left in the compressed image storage area 223. If the compression parameter is changed in step S3011, and the compression processing from step S3005 to step S3010 is repeated several times, the process reaches step S3012.
There is no particular problem since the surplus area should be small. However, in the initial compression using the initial compression parameter, the compression may be more than expected, and the size of the compressed image data may be significantly smaller than the size of the compressed image storage area 223, leaving a surplus area. In the case of irreversible compression, this is nothing but wasting the image quality of the image data.

In step S3012, it is checked how much of the remaining area occupies the entire compressed image storage area 223 in order to keep the image data as high in quality as possible. Then, depending on the ratio, the compression parameter is reset, and the process proceeds to step S3013 to perform the compression process again. On the other hand, if the check of the surplus area is cleared, it is determined that optimal compression has been performed, and the compression processing ends.

An example in which the surplus area in step S3012 occupies a large proportion in the compressed image storage area 223, and the process proceeds to step S3013 in order to perform the compression process again, will be described.
The size of the original image data is 1000 bytes,
The compression processing when the size of the compressed image storage area 223 is 800 bytes will be described. In this embodiment, if the size of the surplus area is less than 20% of the entire size of the compressed image storage area 223 in step S3012, it is determined that the optimal compression has been performed.

First, since the size of the original image data is 1000 bytes and the size of the compressed image storage area 223 is 800 bytes, the desired compression ratio is 80%. In step S3004, the compression ratio is set according to the table in FIG.
Set 72 for the initial compression parameter, expecting 5%.
It is assumed that actual compression is performed in steps S3005 to S3009, and as a result, the size of the compressed image data is 600 bytes. At this time, step S30
10, the size of the compressed image storage area 223 (800
Byte)> the size of the compressed image data (600 bytes), and the process advances to step S3012.

In step S3012, since the compressed image data is 600 bytes, the remaining area 20 out of the 800 bytes in the size of the compressed image storage area 223 is stored.
0 bytes correspond to 25% of the entire size of the compressed image storage area 223. This does not meet the above condition of less than 20%, and the process proceeds to step S3013 to change the compression parameter again.

Here, when the original image data is 10
00 bytes and 600 bytes of image data after compression means that steps S1005 to S100
This means that the actual compression rate of the compression performed at 9 was 60%, which is 20 points less than the expected compression rate of 80%. In the table of FIG. 5, the increase / decrease value of the compression parameter corresponding to the (−20) point is (+10). Therefore, the compression parameter used for the next compression processing is 72 + 10 = 82.
Becomes When a new compression parameter is set, the process proceeds to step S3005, and the compression process is started again using the compression parameter with the initial value set to 82.

As described above, in step S3012, even if the image data is once stored in the compressed image storage area 223, the size of the remaining area is checked to realize the optimum compression for obtaining the highest quality image data. Can be.

As described above, L in the present embodiment is
The BP can control the compression of the image data so that the size of the compressed image data is not too large or small for a storage area for storing the compressed image data, and the image quality is not impaired as much as possible. .

[Second Embodiment] In the first embodiment, when image data is compressed, the compression parameter is changed in some cases, but the compression method itself is not changed. In this embodiment, a plurality of compression methods are prepared,
One compression method is tried, and when it is determined that an expected compression result cannot be obtained due to deterioration in image quality due to compression, reduction in compression processing speed, or the like, the compression method itself is changed.

At this time, the table shown in FIG. 6 is used. In the left column, the compression methods are arranged in order from the top, which means that the compression methods are switched in this order, and the right is a condition that is a switch for switching the compression method. That is, the compression is first performed by the compression method 1, but when the condition 1 is satisfied, the compression processing method is switched to the compression method 2. Similarly, when the compression is performed by the compression method 2 and the condition 2 is satisfied, the compression processing method is switched to the compression method 3. Actually, as a condition for switching the compression method, a compression parameter, a compression processing speed, and the like can be considered.

The procedure for compressing image data by a plurality of compression methods in this embodiment will be described with reference to FIG. However, FIG. 8 shows two new steps (step S80) between step S3004 and step S3005 in FIG.
05, S8006), and the other flow is as described in the first embodiment. In the present embodiment, as shown in FIG.
JPEG and JPEG2000 as compression method 2 are prepared, and the switch condition for switching the compression method from JPEG to JPEG2000 is that the compression parameter of JPEG becomes 60 or less. Note that JPEG
2000 is a compression method that will appear in the near future (2000).
Higher image quality is guaranteed.

Steps S8001 to S800
4 correspond to Step S3 in the first embodiment.
001 to the step S3004. The difference is that in the present embodiment, two compression methods are prepared, and immediately after the start of compression, JPEG compression is selected as the compression method as shown in FIG. Also, in step S8004, the initial compression parameter must be determined.
5 is a table in the format shown in FIG. 4 in which the average compression ratio for each compression parameter in G compression is summarized. When the initial compression parameters are determined, the process proceeds to step S8005.

In step S8005, it is determined whether to change the compression method. If the JPEG compression parameter is 60 or less, the process advances to step S8006.
Otherwise, the process proceeds to step S8007.

The processing after step S8007 has the same flow as the processing after step S3005 described in the first embodiment. In step S8006, step S8006
Since the switch condition is satisfied in 8005, the compression method is changed from JPEG to JPEG2000, and thereafter the compression is performed using JPEG2000. In step S8006, the initial compression parameters in JPEG2000 must be determined. At this time, the table shown in FIG. 4 is used to summarize the average compression ratio for each compression parameter in JPEG2000 compression. When the initial compression parameters are determined, step S800
Proceed to 7.

In step S8013 or step S8015, the compression parameter is changed and the
When returning to 8005, as shown in FIG.
000 has no switch condition to change the compression method. Therefore, in this case, the process proceeds to step S8007.

As described above, in the present embodiment, JPEG and J
PEG2000 and two compression methods were prepared to perform image data compression processing. As described above, by preparing a plurality of compression methods and switching them according to the purpose such as image quality and processing speed, more optimal compression processing can be realized.

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (one device) For example, the present invention may be applied to a copying machine, a facsimile machine, and the like.

Further, an object of the present invention is to supply a storage medium (or a recording medium) on which a program code of software for realizing the functions of the above-described embodiments is recorded to a system or an apparatus, and a computer (a computer) of the system or the apparatus. Or a CPU or MPU) reads out and executes the program code stored in the storage medium,
Needless to say, this is achieved. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.
In addition, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also based on the instructions of the program code,
The operating system (OS) running on the computer performs part or all of the actual processing,
It goes without saying that a case where the function of the above-described embodiment is realized by the processing is also included.

Further, after the program code read from the storage medium is written into the memory provided in the function expansion card inserted into the computer or the function expansion unit connected to the computer, the program code is read based on the instruction of the program code. , The CPU provided in the function expansion card or the function expansion unit performs part or all of the actual processing,
It goes without saying that a case where the function of the above-described embodiment is realized by the processing is also included.

When the present invention is applied to the storage medium described above, the storage medium has the above-described structure (shown in FIG. 3 or FIG. 8).
The program code corresponding to the flowchart is stored.

[0075]

As described above, according to the present invention, the size of the compressed image data must be sufficient for the storage area for storing the compressed image data, and the image quality should not be impaired as much as possible. , The image data can be compressed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an internal structure of an LBP as an image processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a printer control unit 101 of the LBP 100 shown in FIG.

FIG. 3 is a flowchart of a compression processing procedure of image data according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating an example in which, when image data is compressed by a certain compression method, an average compression ratio of image data can be obtained for each compression parameter;

FIG. 5 is a diagram showing an example in which a point and an increase / decrease amount of a compression parameter corresponding to the point are arbitrarily set.

FIG. 6 is a diagram showing a table in which compression methods and conditions for selecting the compression method are described.

FIG. 7 is a diagram showing a specific table of the table shown in FIG. 6 used in the second embodiment of the present invention.

FIG. 8 is a flowchart of a procedure for compressing image data by a plurality of compression methods according to the second embodiment of the present invention.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H04N 5/91 H04N 5/92 H 5/92 7/133 Z 7/30 F term (reference) 2C087 AB01 AB05 AC08 BA02 BA03 BA07 BA09 BD40 5C053 FA04 FA07 FA14 FA23 GA11 GB28 GB36 KA03 KA21 KA24 KA25 LA01 LA03 5C059 KK08 KK27 KK33 MA00 MC38 PP01 PP14 SS14 SS26 TA17 TA57 TA60 TB04 TC15 TC39 TD06 TD12 TD17 UA02 UA05 A07 5A07 5C

Claims (12)

[Claims] An image processing apparatus for compressing image data and storing the compressed image data in a predetermined storage means, wherein the compressed image data can be stored in the predetermined storage means when the image data is compressed. Setting means for setting a compression parameter estimated to give a suitable size; calculating means for calculating a compression ratio when the image data is compressed using the compression parameter; When the size is larger than the size of the storage area of the predetermined storage unit, a change unit that changes the compression parameter according to the compression ratio estimated by the compression parameter and the compression ratio by the calculation unit. And compressing the image data again using the compression parameter changed by the changing means. Image processing apparatus. 2. The image processing apparatus according to claim 1, wherein the changing unit determines that the size of the storage area of the predetermined storage unit is smaller than the size of the storage area of the predetermined storage unit. The image processing apparatus according to claim 1, wherein the compression parameter is changed according to a difference from the size of the image data. And a plurality of compression methods and condition information for selecting each compression method. When the condition described in the condition information is satisfied, the plurality of compression methods are converted into the condition information. A selecting means for selecting a corresponding compression method, wherein the image data is compressed again using the compression method selected by the selecting means and a compression parameter used for the compression method. 1 or 2
An image processing apparatus according to claim 1. 4. The method according to claim 1, wherein the setting unit uses a table in which an estimated compression ratio of the image data is described according to the compression parameter having a value within a predetermined range when setting the compression parameter. Claims 1 to 3
The image processing device according to any one of claims 1 to 4. 5. The change unit, when changing the compression parameter, uses a table in which a change amount of the compression parameter according to a degree of divergence of the compression ratio by the calculation unit with respect to the estimated compression ratio is used. The image processing apparatus according to claim 1, wherein: 6. The apparatus according to claim 1, wherein said changing means uses a table in which a change amount of said compression parameter according to said difference is described when said compression parameter is changed. 2. The image processing device according to claim 1. 7. An image processing method for compressing image data and storing the compressed image data in a predetermined storage means, wherein when the image data is compressed, the image data can be stored in the predetermined storage means. A setting step of setting a compression parameter estimated to give a suitable size; a calculating step of calculating a compression ratio when the image data is compressed using the compression parameter; When the size is larger than the size of the storage area of the predetermined storage unit, a change step of changing the compression parameter according to the compression ratio estimated by the compression parameter and the compression ratio by the calculation step. The image data is compressed again using the compression parameter changed in the changing step. Processing method. 8. The method according to claim 1, further comprising the step of: when the size of the compressed image data is smaller than the size of the storage area of the predetermined storage means, the size of the storage area of the predetermined storage means and the size of the compressed storage area. 8. The image processing method according to claim 7, wherein the compression parameter is changed according to a difference from the size of the image data. 9. The image processing apparatus further includes a plurality of compression methods and condition information for selecting each compression method, and when a condition described in the condition information is satisfied, the plurality of compression methods are converted from the plurality of compression methods to the condition information. A selecting step of selecting a corresponding compression method, wherein the image data is compressed again using the compression method selected in the selecting step and a compression parameter used in the compression method. 9. The image processing method according to 7 or 8. 10. Compression of image data,
A storage medium that stores a program code that functions as an image processing device that stores compressed image data in a predetermined storage unit, and that, when the image data is compressed, gives a size that can be stored in the predetermined storage unit. A program code of a setting step of setting a compression parameter estimated to be; a program code of a calculation step of calculating a compression ratio when the image data is compressed using the compression parameter; A changing step of changing the compression parameter according to the compression ratio estimated by the compression parameter and the compression ratio in the calculation step, when the data size is larger than the size of the storage area of the predetermined storage unit. And using the compression parameters changed in the changing process, A storage medium for recompressing image data. 11. The program code of the changing step, wherein, when the size of the compressed image data is smaller than the size of the storage area of the predetermined storage means, the size of the storage area of the predetermined storage means; The storage medium according to claim 10, wherein the compression parameter is changed according to a difference from a size of the compressed image data. 12. The image processing apparatus further includes a plurality of compression methods and condition information for selecting each compression method, and when the condition described in the condition information is satisfied, the plurality of compression methods convert the condition information to the condition information. A program code for a selecting step of selecting a corresponding compression method, wherein the image data is compressed again using the compression method selected in the selecting step and a compression parameter used for the compression method. Claim 10 or 11
A storage medium according to claim 1.