JP2711045B2 - Image compression device and image decompression 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 compression apparatus and an image expansion apparatus for compressing and expanding a plurality of image data having different magnifications for the same image source.

[0002]

2. Description of the Related Art In a printing plate making operation, an image information of a document (image source) is electrically processed such as performing a scaling process such as an enlargement / reduction process and a resolution changing process to create a plate for plate making. Scanners are widely used. However, in this type of scanner, even if the image subjected to the scaling process is finished, it may be necessary to further change the scaling factor due to various factors. Therefore, in order to quickly respond to such a demand, an image is previously stored in an image database from the same document at different magnifications.
In addition, image data having different magnifications is obtained by enlargement / reduction processing of images such as inflating and thinning.

[0003]

Generally, when an image is stored in an image database, it is necessary to compress the image as small as possible in consideration of the cost of a magnetic recording medium such as a magneto-optical disk. Therefore, when storing an image in the image database, the image data is compressed and stored by a predictive coding method such as a Huffman code or a transform coding method such as an orthogonal transform method.

However, in the above-mentioned conventional configuration, since the images obtained by scanning at different magnifications are individually compressed and stored, it is possible to obtain the effect of compression by a general compression method. However, the compression ratio cannot be increased dramatically. Therefore, image data scanned at different magnifications cannot be efficiently stored in the image database.

Further, in the configuration for performing the image reduction / enlargement processing, there is a problem that the image quality after the reduction / enlargement processing is deteriorated as compared with that before the rotation because the processing includes an error. An object of the present invention is to efficiently compress a plurality of image data having different scaling factors while maintaining image quality. Another object of the present invention is to expand efficiently compressed image data while suppressing image quality deterioration.

[0006]

An image compression apparatus according to the present invention is for compressing and outputting image data to be processed obtained from an image source. This apparatus includes a reference image data acquisition unit, a processing target image data acquisition unit, a scaling process data acquisition unit, a data difference unit, a compression unit, and a data output unit. The reference image data acquisition means is means for obtaining reference image data at a first magnification for the image source. The processing target image data acquiring means is configured to perform a second
This is means for obtaining processing target image data at a magnification. The scaling processing data obtaining means is means for obtaining scaling processing data by scaling the reference image data so that the first magnification matches the second magnification. The data difference means is a means for obtaining a difference between the processing target image data and the scaling processing data to obtain difference image data. The compression means is means for compressing the difference image data to obtain compressed image data. The data output unit is a unit that outputs the reference image data and the compressed image data.

An image decompression device according to the present invention matches reference image data obtained at a first magnification with respect to an image source, processing target image data obtained at a second magnification, and reference image data at a second magnification. In this way, the processing target image data is obtained based on the compressed image data obtained by compressing the difference image data which is the difference from the scaling processing data obtained by the scaling processing. This device includes a decompression unit, a scaling data acquisition unit, and a data addition unit. The decompression means is means for decompressing the compressed image data to obtain difference image data. In the scaling processing data acquisition means, the first magnification is the second magnification.
This is means for obtaining scaling data by scaling the reference image data so as to match the magnification. The data addition means is
This is a means for obtaining data to be processed by adding the difference image data and the scaling processing data.

[0008]

In the image compression apparatus according to the present invention, the reference image data is obtained from the image source at the first magnification by the reference image data obtaining means. Further, the processing target image data obtaining means obtains the processing target image data from the image source at the second magnification. Then, scaling processing data acquisition means performs scaling processing on the reference image data so that the first scaling factor matches the second scaling factor to obtain scaling processing data. Next, the data difference means obtains a difference between the processing target image data and the scaling processing data to obtain difference image data. The obtained difference image data is compressed by the compression means to become compressed image data, and the reference image data and the compressed image data are output by the data output means.

Here, since there is a strong correlation between reference image data, which is image data obtained at different magnifications for a common image source, and data to be processed, difference image data is data having a small difference. It shows a highly biased distribution. Since such biased differential image data is efficiently compressed by the compression means, by handling the efficiently compressed data, for example, the storage capacity of the image data can be reduced, and the data is transferred. Transfer time can be reduced.

In the image decompression device according to the present invention, the decompression means decompresses the compressed image data to obtain difference image data. Then, the scaling processing data acquisition means performs scaling processing to obtain scaling processing data so that the reference image data is the image data of the second magnification. The data adding means adds the difference image data and the scaling processing data to obtain processing target image data.

[0011]

EXAMPLES principle diagram 1 is a block diagram conceptually showing the processing flow of the image compression apparatus and an image decompression apparatus of the present invention. For the same image source OR, the image input unit 101 and the image input unit 10
The compression processing flow for compressing the image data OR (1) and the image data OR (2) obtained at the optical magnification MG (1) and the magnification MG (2) at 2, respectively, will be described.

First, the image data OR (1) is used as reference image data, encoded by the encoding unit 131 as it is, and the compressed image data CMD (1) is stored in the storage unit 141.
On the other hand, the compression processing of the image data OR (2) is performed as follows. Image data OR as reference image data
The magnification processing unit 112 performs magnification processing such as padding and thinning (magnification MG (2) / MG (1)) so that (1) becomes the same as the magnification of the image data OR (2). The processing data J (2) is obtained. Subsequently, the difference between the image data OR (2) and the scaling processing data J (2) is obtained by the differentiator 122, and the difference is used as difference image data DI (2). Image data CMD
(2) is stored in the storage unit 142. Through the above steps, the compressed image data CMD (1) and the compressed image data CMD of the image data OR (1) and the image data OR (2), respectively.
(2) is obtained.

Here, the image data OR (1) and the image data OR (2) are image data obtained from the same image source.
The data has a strong correlation with (2), so that the difference image data DI (2) has a larger distribution of data having a smaller value than the image data OR (2). Therefore, the data amount of the compressed image data CMD (2) obtained by encoding the difference image data DI (2) by the encoding unit 132 is smaller than the data amount obtained by directly compressing the image data OR (2). Can be reduced.

Next, image data OR (1) and image data OR (2) are obtained from the compressed image data CMD (1) and the compressed image data CMD (2) respectively stored in the storages 141 and 142. The decompression processing flow will be described. When obtaining the image data OR (1), the decoding unit 151 directly decodes the compressed image data CMD (1) to obtain the image data OR (1).

On the other hand, when obtaining the image data OR (2), the following is performed. By decoding the compressed image data CMD (2) by the decoding unit 152, the difference image data D
I (2) is obtained. Subsequently, the scaling processing section 162 performs scaling processing (magnification MG (2) / MG (1)) so that the image data OR (1) has the same magnification as that of the difference image data DI (2). The processing data J (2) is obtained. Adder 1
At 72, the difference image data DI (2) and the scaling processing data J
(2) is added to obtain image data OR (2). As described above, the image data O expanded from the compressed image data CMD (1) and the compressed image data CMD (2)
R (1) and image data OR (2) can be obtained.

[0016] Configuration FIG. 2 shows a color scanner which employs an embodiment of the present invention. The color scanner includes an image input unit 1 for inputting an image, and an image processing unit 2 for performing color correction, contour enhancement, magnification change, and the like on image data obtained by the image input unit 1.
And an image recording unit 3 for recording image-processed data on a film, an operation unit 4 for setting these operations and setup conditions, and storing the image data input by the image input unit 1. And a magneto-optical disk drive 5 for the purpose.

An openable / closable lid 7 is provided on the upper surface of the image input section 1.
Is provided. The lid 7 is opened and closed with one side thereof as a center of rotation. A scanning table 6 for mounting a document holder (described later) is provided inside the lid 7. The operation unit 4 mainly includes a personal computer 8 and a color graphic display 13. The personal computer 8 mainly includes a computer main body 9, a keyboard 10, a mouse 11, and a color display 12.

As shown in FIG. 3, the scanning table 6 of the image input unit 1 is movable in the front-back direction (X-axis direction: sub-scanning direction) of the image input unit 1. A document holder 20 is fitted into the scanning table 6. Above the scanning table 6, a light shielding plate 16 fixed to a frame (not shown) of the image input unit 1 is provided. The light shielding plate 16 has a long groove-shaped opening at the center thereof.

Above the light shielding plate 16, a slit member 18 is provided.
Are provided along a Y-axis direction (main scanning direction) orthogonal to the X-axis direction. 5m width at the center of the slit member 18
A slit 18a of about m is formed. The slit member 18 has a flat U-shaped cross section, and a quartz rod 19 is disposed inside the slit member 18. The quartz rod 19
Both ends are supported by brackets erected on the light shielding plate 16. At one end of the quartz rod 19, a halogen lamp 14 for irradiating the quartz rod 19 with light is provided. The light emitted from the halogen lamp 14 can be emitted downward through the quartz rod 19 and the slit 18a.

The scanning table 6 has a rectangular parallelepiped shape, and has a circular opening at the center. On the lower surface of the scanning table 6, guide rails 21 and 21 are juxtaposed at intervals in the Y-axis direction. Guide rails 21, 21
On the upper side, a sliding member 2 fixed to the lower surface of the scanning table 6
2, 22 are mounted. A ball nut 23 is provided on the lower surface of the scanning table 6. A ball screw shaft 24 for moving the scanning table 6 in the X-axis direction is screwed to the ball nut 23. Ball screw shaft 2
4 is connected to a scan motor 25 for rotating it. The scan motor 25 is, for example, a pulse motor with an encoder. Scan motor 25
When the scanning table 6 is driven forward and backward, the scanning table 6 is reciprocated in the X-axis direction.

At the periphery of the circular opening of the scanning table 6,
An annular guide 26 having engagement projections at both ends is provided upright. The annular guide 26 supports a rotary table 27 having a square hole formed in the center so as to be rotatable around a vertical axis. An annular rack 29 is mounted concentrically with the annular guide 26 on the outer periphery of the lower surface of the turntable 27. On the other hand, a pulse motor 31 having a pinion 30 that meshes with the annular rack 29 is provided inside the scanning table 6. The rotary table 27 is guided by the annular guide 26 and rotated by the pulse motor 31.

A document holder 20 for holding the document D strongly against the table surface is mounted in the square hole of the rotary table 27. The document holder 20 has two transparent glasses, and the document D can be set between the transparent glasses. Below the scanning table 6, there is provided a reflecting mirror 35 for changing the optical path of light emitted from a light source (the halogen lamp 14 and the quartz rod 19) and passing through the document D by 90 °. On the exit side of the reflection mirror 35, a lens system 36 including a telecentric adapter lens and the like, and a dichroic prism 37 for separating read light into three primary colors of B, G, and R are arranged. The lens system 36 is movable in the X-axis direction, and is set at a position corresponding to the magnification. The light color-separated by the dichroic prism 37 passes through a slit (not shown) through a blue light reading B-light.
The light is projected on a CCD line sensor 38, a G-CCD line sensor 39 for reading green light, and an R-CCD line sensor 40 for reading red light, respectively. Each line sensor 38,
Numerals 39 and 40 photoelectrically convert the light of the three primary colors into image data for one line of the document.

As shown in FIG. 4, the image input unit 1 and the image processing unit 2 include interface circuits 50 and 47, respectively.
Is connected to the bus 40 via the. The bus 40 is connected to a frame buffer 48 for the color graphic display 13, an interface circuit 49 for the magneto-optical disk device 5, and the image recording unit 3.
The image processing unit 2 performs various types of image processing on the image input by the image input unit 1 based on the setup conditions set by the operation unit 4. The image recording unit 3 records the image input by the image input unit 1 on a film.

Further, the bus 40 is provided with the computer 9
And keyboard 10 and mouse 11 and color display 1
2 are connected. The computer main body 9 mainly includes a semiconductor memory 41, a CPU 42, a hard disk drive (hereinafter, referred to as HDD) 45, and a flexible disk drive (hereinafter, referred to as FDD) 46. The HDD 45 is connected to the bus 40 via the interface circuit 43, and the FDD 4 is connected to the bus 40 via the interface circuit 44. A flexible disk 46a can be mounted on the FDD 46. The semiconductor memory 41 stores input image data, compression processing data,
It has an area for temporarily storing decompression data and the like, and an area for deploying an operation system and application software.

The HDD 45 stores file management information and magnification information of input image data in a table structure as shown in FIG. The file management table 76 includes a document name, a document identification number, the number of files having different magnification parameter conditions in the same document, and a magnification parameter pointer indicating the address of each file name on the magnification parameter table 77. Stored in a table structure. The magnification parameter table 77 includes magnification parameters MG (1), MG corresponding to the magnification parameter pointer.
(2)... And a file name pointer of the magnification parameter are stored. The magneto-optical disk device 5 stores compressed data corresponding to each pointer of the magnification parameter table 77. Here, the reference image data is, for example, image data that is directly compressed and directly stored in the magneto-optical disk device 5, and the processing target image data is a scaling process data of the reference image data. This is the data for which the difference processing is performed using the data.

As shown in FIG. 6, an operation system 71, a scanner program 72 for controlling the scanner, a command table 73 referred to in the scanner program 72, and a A front-end processor 74 used during execution and a dictionary 75 used by the front-end processor 74 are stored.

The reason why the file management table 76 and the magnification parameter table 77 are stored in the HDD 45 is as follows.
This is because these file information and management information need to be accessed at high speed at the time of retrieval. On the other hand, since the compressed data does not need to be accessed at high speed, it is stored in the magneto-optical disk device 5. Here, the operation of the above-described embodiment will be described while explaining the contents of the scanner program 72. 7 to 1
0 is a control flowchart of the scanner program 72. First, the flexible disk 46a is set in the FDD 46 of the personal computer 8, and the contents of the flexible disk 46a are taken into the personal computer 8. When the scanner program 72 starts up based on the automatic start-up function of the operation system 71, the scanner program 72 shown in FIGS. 7 to 10 is executed.

In step S1 of FIG.
Initial setting such as initialization of 1 is performed. Then step S
In steps S2 to S6, the process waits for an operator command from the keyboard 10. If a command for setting various conditions such as magnification is input, the process moves from step S2 to step S7, and a condition setting subroutine shown in FIG. 8 is executed. If a compression command is input, program steps S3 to S8 are executed.
Then, the compression processing subroutine shown in FIG. 9 is executed. If an extension command is input, the program proceeds to step S
4 to step S9, and the decompression processing subroutine shown in FIG. 10 is executed. If another command is input, the program proceeds from step S5 to step S18,
Other processing is performed according to the input command. If an end command is input, the determination in step S6 becomes YES, and the program ends.

In the condition setting processing subroutine shown in FIG. 8, first, in step S10, a variable m indicating the number of inputs is set to "1".
Set to. In step S11, a document name and a document identification number are received from the operator. In step S12, a file name corresponding to the image magnification (magnification parameter) is received from the operator. In step S13, a magnification parameter MG (m) is received from the operator. When the magnification parameter is received, the data is transferred to the image input unit 1 when the image is compressed, and the lens system 36 is set at a position corresponding to the magnification parameter. In step S14, it is determined whether an end command has been issued. If the end command has not been issued, the process proceeds to step S16, the variable m is incremented, and the process returns to step S12 to set the file name of the next magnification parameter. If it is determined that the end command has been issued, the process proceeds from step S14 to step S15. In step S15, the document name, document identification number, file number m, and magnification parameter pointer are registered in the file management table 76, and the magnification parameter, file name pointer, and the like are registered in the magnification parameter table 77. Further, the area of the magneto-optical disk device 5 is secured by the data of the number of files.

In the compression processing subroutine shown in FIG. 9, a variable x is set to 1 in step S21. The variable x is a variable for counting the number of input files. In step S22, the magnification parameter MG (1) (normally the same magnification) is transferred to the image input unit 1. The image input unit 1 moves the lens system 36 in the X-axis direction, sets the lens system 36 at the position indicated by the transferred magnification parameter MG (1), and performs scanning.
In step S23, the scanned image is input as reference image data OR (1). In step S24, the input reference image data OR (1) is compressed by a compression method such as a Huffman code or an orthogonal transform coding method, and the compressed data CMD
(1) is stored in the HDD 45.

In step S25, the variable x is incremented. In step S26, it is determined whether or not the variable x has exceeded the set number m of files. If the number of files does not exceed the set number m, the process proceeds from step S26 to step S27. In step S27, the magnification parameter MG is set based on the incremented variable x.
(X) is transferred to the image input unit 1, the lens system 36 of the image input unit 1 is moved in the X-axis direction, and the magnification parameter MG (x)
Set to the position indicated by. In step S28, the next processing target image data OR (x) is input based on the incremented variable x. In step S29, the first input reference image data OR (1) is converted to a magnification parameter MG.
Enlargement / reduction processing is performed by (x) / MG (1) to obtain scaling processing data J (x). For this enlargement / reduction processing, a known scaling processing method such as a simple padding / thinning processing may be used. Here, the reason why the simple inflating / thinning processing is used is that the precision of the data is not particularly required because the scaling processing data J (x) is only data that becomes a reference at the time of decompression. It should be noted that the scaling method need not be limited to the method described above, and other scaling methods such as a hierarchical enlargement / reduction method using a Lagrange polynomial may be used.

In step S30, the image is enlarged /
Reduction processing data J (x) subjected to reduction processing and image input unit 1
Is subtracted from the processing target image data OR (x) obtained by performing magnification processing at the magnification indicated by the magnification parameter MG (x), and difference image data DI (x) is calculated. Step S
At 31, the calculated difference image data DI (x) is compressed by a compression method such as orthogonal transformation or vector transformation to obtain compressed image data CMD (x). When this process ends, the process returns to the step S25.

If it is determined in step S25 that image data for the set number m of files has been input, step S3 is reached.
Move to 2. In step S32, it is determined whether to store the obtained compressed image data CMD (1) to CMD (m) in the magneto-optical disk device 5 or to transmit the compressed image data to another device. When transmitting to another device, the process proceeds to step S33, and transmission to another device is performed. If the data is to be stored in the magneto-optical disk device 5, the process proceeds to step S34, where the data is transferred to the magneto-optical disk device 5 and stored. When these processes are completed, the process returns to the main routine.

In the decompression subroutine shown in FIG. 10, first, in step S41, a file name for selecting a file name from the files stored in the magneto-optical disk device 5 is input. In step S42, a magnification MF is specified.
The magnification MF specified here may not be the same as the magnification parameter MG (x) set in the condition setting processing subroutine. In step S43, a magnification parameter MG (x) approximating the specified magnification MF is selected. In step S44, the compressed image data CMD (1) is expanded.
By this expansion, reference image data OR (1) is obtained. In step S45, the expanded reference image data OR
(1) is displayed on the color graphic display 13.

In step S46, a determination as to whether the displayed reference image data is a desired image is received from the operator. If the image is not the desired image, the process returns to step S41 and repeats from the input of the file name. If it is determined that the image is the desired image, the process proceeds to step S47. In the step S47, it is determined whether or not the variable x is “1”. Variable x is "1"
If not, the process moves to step S48. In step S48, the reference image data OR (1) is stored in step S4.
The enlargement / reduction processing is performed by MG (x) / MG (1) which is the ratio between the magnification parameter MG (x) selected in Step 3 and the magnification parameter MG (1) of the reference image data OR (1), and the magnification processing is performed. Obtain data J (x). In step S49, the compressed image data CMD stored in the optical disk drive 5 is stored.
(X) is expanded to obtain difference image data DI (x). In step S50, the scaling processing data J (x) and the difference image data DI (x) are added, and the processing target image data O (x) is added.
Obtain R (x). In step S51, enlargement / reduction processing is performed on the processing target image data OR (x) at a ratio MF / MG (x) of a scaling parameter MG (x) and a specified magnification MF. In step S52, the obtained image data IM is output to the image processing unit 2 for editing.

If the variable x is "1" in step S47, the process proceeds to step S51. Step S51
Then, the reference image data OR (1) is converted into the magnification parameter MG.
Enlargement / reduction processing is performed at the ratio between (x) and the designated magnification MF. As described above, in this embodiment, the magnification parameter MG
Only the compressed image data of the reference image data OR (1) of (1) is stored, and the processing target image data OR (2) to OR (m) of other magnification parameters are stored.
Is the scaled image data J (2) obtained by the enlargement / reduction processing
-Difference image data DI (2) which is a difference from J (m)-
Only the compressed data of DI (m) is stored. Therefore, the data capacity can be reduced. Here, the distribution of the difference data obtained by taking the difference between the image data to be processed and the image data subjected to the scaling process, in which the original is common, has a bias in the distribution based on the correlation between the images. For this reason, when compression is performed by a known compression method, the compression efficiency is dramatically increased as compared with the case where image data having a uniform distribution is compressed. For this reason, the amount of data to be handled is reduced, and when these are stored in a database and stored, they can be stored efficiently, and when these are transferred, the transfer time can be reduced.

[Other Embodiments] (a) In the above embodiment, the enlargement / reduction processing and the compression / expansion processing are performed by software. However, these may be realized by dedicated hardware. . FIG. 11 shows an example in which the compression / decompression processing unit 100 is configured by dedicated hardware. Here, the compression / decompression processing unit 100 is connected to the bus 40. The compression / decompression processing unit 100 includes, as shown in FIG.
4, a decompression processing unit 65, and a control unit 66.

The compression processing section 64 is adapted to store the reference image data OR
A selector 51 for selecting (1) and processing target image data OR (2) to OR (m); and reference image data OR (1)
52, an enlargement / reduction processing unit 53 that enlarges / reduces the reference image data OR (1) by the magnification parameter, and scaled image data J (x) that has undergone enlargement / reduction processing
A difference unit 54 for obtaining a difference between the image data OR (x) and the processing target image data; an encoder 55 for compressing and encoding the reference image data OR (1) and the difference image data DI (x) by the above-described compression method; And a buffer 56 for temporarily storing the compressed image data CMD (x). These units are controlled by the control unit 63.

The decompression processing unit 65 includes a buffer 57 for temporarily receiving the compressed image data, a decoder 58 for decompressing the compressed image data, and an expanded reference image data OR.
(1), a selector 59 for selecting the difference image data DI (x), a memory 60 for storing the reference image data OR (1), and a reference image data O stored in the memory 60.
Enlargement / reduction processing unit 61 for enlarging / reducing R (1)
And the data J (x) subjected to the scaling process and the difference image data D
I (x) and reference image data O
R (1) and processing target image data OR (2) of the addition result
ＯＲOR (m) is a magnification parameter MG (x) and a designated magnification M
Enlargement / reduction processing unit 63 that performs enlargement / reduction processing by the ratio of F
It is mainly composed of Each of these units is a control unit 66
Is controlled by

The control unit 66 switches the selector 51 in accordance with the information indicating the file name from the CPU 42. That is, the magnification parameter MG whose file name is the reference
In the case of the file indicating (1), the reference image data OR
Switch to the (1) side, otherwise switch to the processing target image data OR (2) to OR (m) side. Further, the control unit 66 switches the selector 59 according to the address information from the CPU 42. That is, when the reference image data OR (1) of the magneto-optical disk device 5 is acquired, the selector 59 is switched to the reference image data side, and in other cases, the selector 59 is switched to the difference image data side.

The compression / compression by such hardware processing
By performing the decompression processing and the enlargement / reduction processing, the processing can be performed at a higher speed than in the case of using software. Note that these hardware may be configured by a digital signal processor (DSP). (B) In the above embodiment, the Huffman code or the orthogonal transform coding method has been described as an example of the compression / decompression method, but any of these known compression / decompression methods may be used. Is also good. (C) In the above embodiment, the reference image data is compressed and stored in order to increase the compression efficiency, but may be stored without compression.

[0042]

According to the image compression apparatus of the present invention, the difference between the scaling processing data obtained from a common image source and the reference processing target image data is obtained and the difference image data is compressed, so that the image quality is maintained. While increasing the compression efficiency. For this reason, it is possible to compress the image data to be processed more efficiently than when the image data is compressed as it is. For example, when storing the image data, the capacity is reduced, and when transferring it, the transfer time is shortened.

Further, in the image decompression apparatus of the present invention, since the image data actually obtained by scanning is decompressed by the addition, it is possible to decompress the image data which has been efficiently compressed without deteriorating the image quality. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the principle of the present invention.

FIG. 2 is a perspective view showing the appearance of a color scanner equipped with an image compression / decompression device according to one embodiment of the present invention.

FIG. 3 is a partially cutaway perspective schematic view showing a configuration of a main part of an image input unit.

FIG. 4 is a block diagram showing a configuration of a control system of the color scanner.

FIG. 5 is a view showing data storage contents of a hard disk drive and a magneto-optical disk device.

FIG. 6 is a diagram showing stored contents of a flexible disk.

FIG. 7 is a control flowchart of a scanner program.

FIG. 8 is a control flowchart of a scanner program.

FIG. 9 is a control flowchart of a scanner program.

FIG. 10 is a control flowchart of a scanner program.

FIG. 11 is a block diagram illustrating a configuration of a control system of a color scanner according to another embodiment.

FIG. 12 is a control block diagram of a compression / decompression processing unit according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image input part 2 Image processing part 3 Image recording part 4 Operation part 8 Microcomputer 9 Computer main body 42 CPU 100 Compression / expansion processing part

Claims (2)

(57) [Claims] 1. An image compression apparatus for compressing and outputting image data to be processed obtained from an image source, comprising: a reference image data acquisition unit for obtaining reference image data at a first magnification for the image source; A processing target image data obtaining means for obtaining the processing target image data at a second magnification with respect to the image source; and performing scaling processing on the reference image data so that the first magnification matches the second magnification. Scaling processing data acquisition means for obtaining double processing data; data difference means for obtaining difference between the processing target image data and the scaling processing data to obtain difference image data; and compressing the difference image data to obtain a compressed image. An image compression apparatus comprising: compression means for obtaining data; and data output means for outputting the reference image data and the compressed image data. 2. A scaling process for a reference image data obtained at a first magnification with respect to an image source, processing target image data obtained at a second magnification, and the reference image data so as to match the second magnification. An image decompression device for obtaining processing target image data based on compressed image data obtained by compressing differential image data that is a difference from scaling processing data obtained by performing Decompression means for decompressing data to obtain the differential image data; and scaling processing data for obtaining the scaling processing data by scaling the reference image data so that the first magnification matches the second magnification. An image decompression device comprising: an acquisition unit; and a data addition unit that adds the difference image data and the scaling processing data to obtain the processing target image data.