JP2000295480A - Image processing unit and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce data processing time and to decrease the consumed capacity of a storage medium by applying rotation processing to image data obtained from an original image, so as to make the image data coincide with a direction providing efficient compression and applying compression processing to the rotated image data. SOLUTION: An image memory 26 temporarily stores image data received from a scanner 23, and a character/image discrimination section 31 discriminates whether the image data are character image data or a photographic or illustration image data and the like, other than the character image data. In the case that the image data represents a character image, a sentence direction discriminating section 32 discriminates whether the arrangement of the image data coincides with the direction of a sentence or vertical to the direction of the sentence. When the arrangement of the image data is coincident with the direction of the sentence, a companding processing section 28 applies compression processing to the image data without modifications. When the arrangement of the image data is vertical to the direction of the sentence, a rotation processing section 27 rotates the image data by 90 degrees, and then the companding processing section 28 applies compression processing to the rotated image data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image processing apparatus and an image forming apparatus for compressing input image data in a digital copying machine, a personal computer, or the like.

[0002]

2. Description of the Related Art In an image processing apparatus which is used in a digital copying machine or the like and compresses input image data read by an image reading apparatus and stores it in a storage medium such as a hard disk, the compression scanning direction of the conventional input image data is as follows. It depends on the direction of scanning of the original by the image reading device, and is fixed to be the same as the scanning direction of the original.

[0003]

Conventionally, the compression direction of input image data in an image processing apparatus has been fixed regardless of the content of the image data. For this reason, depending on the input image data, the compression efficiency is low, the size of the compressed data is large, the input / output performance of the compressed data to the storage medium is reduced, the processing time is required, and the required capacity of the storage medium is increased. Had.

Accordingly, the present invention has been made to solve the above-mentioned problem, and the data processing time can be shortened by increasing the compression efficiency and reducing the size of the compressed data regardless of the characteristics of the input image data. The purpose of the present invention is to reduce the used capacity of the device.

[0005]

According to the present invention, as means for solving the above problems, there is provided image input means for inputting image data obtained from a document image, and the image data inputted from the image input means. Direction detecting means for detecting an efficient compression direction of a document image; rotating means for rotating the image data so that the arrangement of the image data coincides with the efficient compression direction; Compression means for compressing the rotated data, data storage means for storing compressed data formed by the compression means, and expansion processing and rotation processing of the compressed data stored in the data storage means. Restoring means for restoring image data.

According to another aspect of the present invention, there is provided an image input means for inputting image data obtained from an original image, and an efficient method for converting the original image from the image data input by the image input means. Direction detecting means for detecting a proper compression direction, rotating means for rotating the image data so that the arrangement of the image data coincides with the efficient compression direction, and compressing the rotated data after the rotating processing by the rotating means. Compression means for processing, data storage means for storing compressed data formed by the compression means, and expansion and rotation processing of the compressed data stored in the data storage means to restore the image data A restoring means; and an image output means for forming a print image based on the image data restored by the restoring means.

With the above arrangement, the present invention reduces the size of the compressed data by rotating the image data in a direction to obtain an efficient compression in accordance with the content of the input image data and then compressing the image data. The object of the present invention is to shorten the data processing time, reduce the used capacity of the storage medium, and improve the functions.

According to another aspect of the present invention, there is provided an image input unit for inputting image data obtained from an original image, and the image data input by the image input unit is transmitted to an arbitrary part of the original image. Image dividing means for dividing each area; direction detecting means for detecting an efficient compression direction of the divided data for each area divided by the image dividing means; Rotation means for rotating the divided data so as to match the data, compression means for compressing the divided rotation data of the rotation processing by the rotation means, and data storage means for storing the divided compressed data formed by the compression means And decompression means for decompressing and rotating the divided compressed data stored in the data storage means to decompress the divided data. Is shall.

According to another aspect of the present invention, there is provided an image input unit for inputting image data obtained from an original image, and the image data input by the image input unit may be arbitrarily selected from the original image. Image dividing means for dividing each area; direction detecting means for detecting an efficient compression direction of the divided data for each area divided by the image dividing means; Rotation means for rotating the divided data so as to match the data, compression means for compressing the divided rotation data after the rotation processing by the rotation means, and data storage for storing the divided compressed data formed by the compression means. Means,
A restoring means for decompressing and rotating the divided compressed data stored in the data storage means to restore the divided data; and a reconstructing means for reconstructing the divided data restored by the restoring means into the image data. Constituent means,
And image output means for forming a print image based on the image data reconstructed by the reconstructing means.

According to the present invention, according to the present invention, the image data in a necessary area is rotated in a direction in which efficient compression can be obtained and then compressed in accordance with the content of the input image data, whereby the content of the image data is further increased. Thus, the size of compressed data can be further reduced, the data processing time can be further reduced, the used capacity of a storage medium can be further reduced, and functions can be further improved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the principle of the present invention will be described with reference to FIG. FIG. 1 shows a system configuration of a digital copying machine 1. A scanner 4, a printer 6, and an image processing device 7 are connected to a CPU 3 by a common bus 2. The image processing device 7 includes an image memory 8, a compression / decompression processing unit 10,
It consists of a hard disk 11. The memory 3 is connected to the CPU 3.

In such a digital copying machine 1, when normal copying is performed one by one in each case corresponding to a document at the time of image formation, the image data read by the scanner 4 is directly transferred to the printer 6. In the case of forming a copy image of a plurality of copies using a plurality of originals, image data read by the scanner 4 is temporarily stored in the image processing device 7, and then sequentially stored in the image processing device 7. The image data is transferred to the printer 6 to obtain a plurality of copy images.

In general, the operation of storing image data in the image processing apparatus 7 is described as “temporarily storing image data from the scanner 4 in the image memory 8,
The compressed data is transferred to the hard disk 11 and stored. Is sequentially performed on all the originals. After this, the printer 14
When a copy image is formed by printing, the operation of storing the compressed data is the reverse of the operation of storing the compressed data.
1 is decompressed by a compression / decompression processing unit 10 to restore image data, and the restored image data is temporarily stored in an image memory 8;
To the printer 8. Are sequentially performed. Further, the print forming process is repeated to obtain a required number of copies of the copied image.

Here, in order to increase the number of processed images per unit time so as to increase the speed of the image forming apparatus 1, the operation time of storing image data in the hard disk 11 in the image processing apparatus 7 and the time required In order to reduce the reading operation time, it is necessary for the compression / decompression processing unit 10 to compress the image data as small as possible. In order to save the limited storage capacity of the hard disk 11,
It is necessary to reduce compressed data per sheet as much as possible.

On the other hand, in the case of image data, compression efficiency is higher for data in which pixel information of the same element is continuous than in the case where adjacent pixel information is scattered. For example, when image data is character data. For example, when the image is compressed along the text direction, a higher data compression rate can be obtained than when the image is compressed in the text direction and the vertical direction.

Therefore, in the present invention, based on the above principle, image data is compressed and scanned in the direction of high compression efficiency in which pixel information of the same element is continuous to reduce the size of the compressed data.

Hereinafter, the present invention will be described with reference to the first embodiment shown in FIGS. FIG. 2 shows a system configuration of a digital copying machine 20 as an image forming apparatus.
The PU 22 has a scanner 23 as an image input unit for reading a document (not shown), a printer 24 as an image output unit for printing out image data, and processes image data input from the scanner 23 and transfers the image data to the printer 24. Image processing device 25 is connected. Image processing device 25
An image memory 26 for temporarily storing the image data input from the scanner 23, a rotation processing unit 27 for rotating the image data, a compression / decompression processing unit for compressing the image data or expanding the compressed image data 28, a hard disk 30 for storing the compressed data compressed by the compression / decompression processing unit 28, and a character image determination unit 3 for determining whether the image data is a character image or another image such as a photograph or illustration
1. Text direction determination unit 3 for determining the text direction of character data
Consists of two. The CPU 22 includes a scanner 2
3. A memory 33 composed of a ROM for storing control programs for the printer 24 and the image processing device 25, and a RAM for storing data from the scanner 23 and image processing conditions.
Is connected.

Next, the operation will be described. First, when a normal copy is to be performed partly each time corresponding to a document, the document image is first read by the scanner 23, and the read image data is directly transferred to the printer 24 via the common bus 21 to form a copy image. .

On the other hand, in the case of a copy operation using a sort function for copying a plurality of copies of a plurality of documents, image data of the plurality of documents is temporarily stored in the image processing device 25, and the stored data is stored in the printer 24. To form a copy image. That is, after the document image is read by the scanner 23, the image data of the document image is temporarily stored in the image memory 26 in the image processing device 25. Thereafter, the image data is compressed by the compression / decompression processing unit 28, and the compressed data is stored in the hard disk 30. When a copy image is printed and formed by the printer 24, the compressed data stored in the hard disk 30 is decompressed by the compression / decompression processing unit 28 to restore the image data, and the restored image data is temporarily stored in the image memory 26. Memorize and then printer 2
4 to form a copied image. Furthermore, this printer 24
Is repeated to obtain the required number of copies.

Next, the compression processing of image data in the image processing device 25 will be described in detail with reference to the flowchart shown in FIG. After the image data input from the scanner 23 is temporarily stored in the image memory 26, in step 100, the character image determination unit 31 determines whether the image data is a character image or another image such as a photograph or illustration. . If it is not a character image, the process proceeds to step 103, where the compression / decompression processing unit 28 directly compresses the image data.

If the image data is a character image, the process proceeds to step 101, where the sentence direction determining unit 32 determines whether the arrangement of the image data matches the sentence direction or is perpendicular to the sentence direction. . If the arrangement of the image data matches the sentence direction, the process proceeds to step 103, where the compression / decompression processing unit 28 directly compresses the image data. If the image data is in the vertical direction with respect to the text direction, the process proceeds to step 102 and the rotation processing unit 27
After the 0 ° rotation processing, the process proceeds to step 103, where the compression / decompression processing unit 28 compresses the rotated image data.

That is, as shown in FIG.
When the upper sentence direction is parallel to the reading scanning direction in the arrow s direction by the scanner 23 and the image data is arranged in the sentence direction, the compression processing is performed as it is because the data compression efficiency is high, while FIG. As shown in b), when the text direction on the document 36 is perpendicular to the scanning direction of the arrow s read by the scanner 23 and the image data array is perpendicular to the text direction, the image data is set to 90 °.
After rotation, the text direction is made to match the scanning direction of the arrow s by the scanner 23 to increase the data compression efficiency, and then the data is compressed. As shown in FIG. 5, the rotation information indicating whether or not the image data has been rotated during the compression process for all the originals is stored in the management table 33a of the memory 33.

In step 103, the image data is compressed, and the compressed data is stored in the hard disk 30. Next, for printing the copied image, the compressed data stored in the hard disk 30 is expanded by the compression / expansion processing unit 28, and then, based on the rotation information in the management table shown in FIG. The image data rotated in the direction 90
After returning, the image data is restored and stored in the image memory 26 and transferred to the printer 24 to form a copied image.

With this configuration, when the image data input from the scanner 23 is character data, the image data is rotated so that the text direction of the character data and the compression scanning direction are matched to increase the compression efficiency. After compression, the size of the compressed data can be further reduced, the processing time of the image data can be shortened, the used capacity in the hard disk 30 can be reduced, and the performance of the image processing apparatus and the image forming apparatus can be improved.

Next, the present invention will be described with reference to a second embodiment shown in FIGS. In the present embodiment, an input image is divided into a plurality of regions, and character data is rotated for each divided image region so that the text direction and the compression scanning direction match, and then image compression is performed. Therefore, the same portions are denoted by the same reference numerals and description thereof will be omitted. The image processing device 36 of the digital copying machine 35 shown in FIG.
7. The compression / decompression processing unit 28, the hard disk 30, the character image determination unit 31, the text direction determination unit 32, and the character image determination unit 31 and the text direction determination unit 32 recognize the character area and the other area, or It comprises an image division reconstruction processing unit 37 that recognizes an area for each direction, divides an image into respective areas, and reconstructs the divided areas.

Next, referring to a specific example, the image processing device 36
The following describes the compression processing of image data in the inside. (Specific Example 1) As shown in FIG. 7, a specific example 1 includes first character data 38a, photograph data 38b, and second character data 3b.
The original 40 on which the image data 38 composed of 8c is displayed is
When performing a copy operation using the sort function, the image area of the document 40 is divided into fixed regions. The first image above the line LL 'by the image division reconstruction processing unit 37 of the image processing device 36
, A divided area 40a including character data 38a and photo data 38b, and second character data 3 below the line LL '.
8c is divided into fixed upper and lower half regions of the divided region 40b. Then, the text direction judging unit 32 determines that the text direction of the first character data 38a in the upper divided area 40a is perpendicular to the compression scanning direction in the direction of the arrow t, while the second character in the lower divided area 40b is It is determined that the text direction of the data 38c matches the compression scanning direction of the arrow t.

Therefore, the divided image data of the lower divided area 40b is directly compressed by the compression / expansion processing unit 28, while the divided image data of the upper divided area 40a is processed by the rotation processing unit 27 in order to improve the compression efficiency. After the rotation process, the divided compressed data formed for each divided region formed by compression processing by the compression / decompression processing unit 28 is stored in the hard disk 30. In the management table of the memory 33, rotation information about each of the upper divided area 40a and the lower divided area 40b of the document 40 is stored.

Next, for printing a copied image, the divided compressed data stored in the hard disk 30 is decompressed by the compression / decompression processing unit 28, and thereafter, based on the rotation information of the management table stored in the memory 33, the pre-compression processing is performed. The divided image data of the upper divided region 40a rotated by 90 ° is returned by 90 °, and the upper and lower divided regions 40a, 4
0b is reconstructed to restore the image data,
And transfer it to the printer 24 to form a copy image.

As a result, the text direction of the first character data 38a of the divided image data in the upper divided area 40a matches the compression scanning direction, and the compression efficiency of the divided image data is improved. Can be made smaller,
As a result, the compressed data size of the entire image data 38 of the document 40 can be reduced.

(Specific Example 2) As shown in FIG. 8, the specific example 2 includes the third character data 42a and the first illustration data 4a.
Document 43 on which image data 42 including 2b, second illustration data 42c, and fourth character data 42d is displayed
When a copy operation is performed using the sort function, the image area of the document is arbitrarily divided according to the contents of the image data 42. The image of the document 43 is converted by the character image determination unit 31 of the image processing device 36 into the A divided area 43 starting from the point A.
a has third character data 42a, a B illustration area 43b starting from point B has first illustration data 42b, and a C illustration area 43c starting from point C has second illustration data 42c. It is determined that there is the fourth character data 42d in the D division area 43d starting from the point D, and the image division reconstruction processing unit 37 determines that the fourth character data 42d
The image is divided into divided areas 43a to 43d starting from points, points C and D.

The sentence direction judging section 32 sets the A divided area 43
a, the text direction of the third character data 42a is perpendicular to the compression scanning direction in the direction of the arrow u, while the text direction of the fourth character data 42d in the D divided area 43d is the direction of the arrow u
It is determined that the direction matches the compression scanning direction.

Therefore, the B, C, and D divided areas 43b to 43b
The 3d divided image data is directly compressed by the compression / decompression processing unit 28, while the third character data 42a in the A divided area 43a is rotated by 90 ° by the rotation processing unit 27 in order to improve the compression efficiency, and then compressed / decompressed. The compression processing is performed by the processing unit 28, and the divided compressed data formed for each of the divided areas 43a to 43d is stored in the hard disk 30.

In the management table of the memory 33, as shown in FIG. 9, the position information of the starting points A to D of the divided areas 43a to 43d and the width and height of each of the divided areas 43a to 43d are stored. Before the compression processing, each divided area 43a-43
The rotation information of d is stored.

Next, for printing a copied image, the divided compressed data stored in the hard disk 30 is decompressed by the compression / decompression processing unit 28, and then, based on the rotation information of the management table stored in the memory 33, the pre-compression processing is performed. The divided image data of the rotated region is returned by 90 °, and the image data is restored by reconstructing the divided regions 43a to 43d based on the position information and the size information of the management table in the image division reconstruction processing unit 37. The image is stored in the memory 26 and transferred to the printer 24 to form a copy image.

Thus, the image area of the original 43 can be divided into A divided areas 43a to D divided areas 43a according to the contents of the image data.
d, the divided data of the A divided area 43a is rotated, and the text direction of the third character data 42a matches the compression scanning direction, thereby improving the compression efficiency of the divided image data in the A divided area 43a. As a result, the compressed data size of the third character data 42a in the A-divided area 43a can be made smaller, and the compressed data size of the entire image data 42 of the document 43 can be made smaller.

According to the present embodiment, a document is divided into a plurality of areas, and in an area where image data needs to be rotated in order to match the text direction of character data with the compression scanning direction, the divided image data By rotating and compressing, the compression efficiency can be improved for each area according to the image content of the original, the compressed data size can be reduced more effectively, and the processing time of the image data can be shortened and The capacity used in the hard disk 30 can be efficiently reduced, and the performance of the image processing apparatus and the image forming apparatus can be further improved.

Next, the present invention will be described with reference to FIGS.
This will be described with reference to the embodiment. In the present embodiment, a distribution direction of pixels for each line of image data in a plurality of scanning directions is compared to detect a line direction having a high compression efficiency, and this line direction matches the compression scanning direction of the image data. In this way, image data is compressed after rotating the image data.
Other parts are the same as those of the first embodiment, and therefore the same parts are denoted by the same reference numerals and description thereof will be omitted. The image processing device 46 of the digital copying machine 45 shown in FIG. 10 includes an image memory 26, a rotation processing unit 27, a compression / decompression processing unit 28, a hard disk 30, a frequency counter 47, and a flat direction determination unit 48. The frequency counter 47 is means for calculating the total number of pixels (frequency) for each line of input image data.
The frequency of each line obtained in step 7 is compared with a predetermined upper threshold and a predetermined lower threshold, and the sum of the number of lines exceeding the upper threshold and the number of lines falling below the lower threshold is obtained. This is a means for selecting a flat direction.

Next, referring to a specific example, the image processing device 36
The following describes the compression processing of image data in the inside. (Specific Example 3) As shown in FIG. 11, a document 50 having image data in which a pixel portion 50a and a non-pixel portion 50b are arranged.
Is copied using the sort function, first, FIG.
The frequency counter 4 of the image processing device 46 as shown in FIG.
At 7, the frequency which is the sum of the pixel units 50a for each line of the image data in the arrow v direction along the compression scanning direction is obtained, and then the flat direction determining unit 48 determines that the frequency is equal to or higher than the upper threshold (3). A total of 1 is obtained for the number of lines and the number of lines below the lower threshold (1). On the other hand, as shown in FIG. 12B, the frequency counter 47 of the image processing device 46 calculates the frequency that is the sum of the pixel units 50a for each line of the image data in the arrow w direction perpendicular to the compression scanning direction. Next, the flat direction determination unit 48 obtains a total of 4 of the number of lines whose frequency is equal to or higher than the upper threshold value (3) and the number of lines whose frequency is equal to or lower than the lower threshold value (1).
Comparing the number of lines 1 in the direction and the number of lines 4 in the direction of the arrow w, it is determined that the direction of the arrow w is a flat direction and the direction of the compression efficiency is high because the direction of the arrow w is large.

Therefore, in order to improve the compression efficiency of the image data, the image data is rotated by 90 ° so that the direction of the flat line is
The data is compressed by the compression / decompression processing unit 28 to increase the data compression efficiency in accordance with the compression scanning direction, and the compressed data is stored in the hard disk 30. The rotation information for each document is stored in the management table of the memory 33.

Next, in order to print a copied image, the compressed data stored in the hard disk 30 is expanded by the compression / expansion processing unit 28, and then, based on the rotation information in the management table stored in the memory 33, the data is rotated before the compression processing. The rotated image data is returned by 90 ° in the direction opposite to the compression process by the rotation processing unit 27, and after the image data is restored, the image data is stored in the image memory 26.
The image is transferred to the printer 24 to form a copy image.

Thus, after detecting a flat line direction having high compression efficiency not only for character data but also for image data, the image data is compressed after rotating the image data so as to increase the compression efficiency by matching the flat line direction with the compression scanning direction. Therefore, the size of the compressed data can be further reduced, the processing time of the image data can be reduced, the capacity used in the hard disk 30 can be reduced, and the performance of the image processing apparatus and the image forming apparatus can be improved. (Specific Example 4) As shown in FIG. 13, a document 51 having image data in which a pixel portion 51a and a non-pixel portion 51b are arranged.
Is copied using the sort function, first, FIG.
The frequency counter 4 of the image processing device 46 as shown in FIG.
At 7, the frequency which is the sum of the pixel portions 51a of every other line of the image data in the arrow v direction along the compression scanning direction is obtained, and then the frequency is determined by the flat direction determination section 48 to be equal to or higher than the upper threshold (5). The total 0 of the number of lines and the number of lines equal to or less than the lower threshold (1) is obtained. On the other hand, as shown in FIG. 14B, the frequency counter 47 of the image processing device 46 calculates the frequency which is the sum of the pixel portions 51a of every other line of the image data in the direction of the arrow w perpendicular to the compression scanning direction. Then, the flat direction determination unit 48 obtains a total of 2 of the number of lines whose frequency is equal to or more than the upper threshold (5) and the number of lines equal to or less than the lower threshold (1), and determines the number of lines 0 in the arrow v direction and the number of lines in the arrow w direction. As compared with Equation 2, since the direction of the arrow w is large, it is determined that the direction of the arrow w is the flat direction and the direction of the line with high compression efficiency.

Therefore, in order to improve the compression efficiency of the image data, the image data is rotated by 90 ° to change the direction of the flat line.
The data is compressed by the compression / decompression processing unit 28 to increase the data compression efficiency in accordance with the compression scanning direction, and the compressed data is stored in the hard disk 30. The rotation information for each document is stored in the management table of the memory 33.

Next, in order to print a copied image, the compressed data stored in the hard disk 30 is expanded by the compression / expansion processing unit 28, and then, based on the rotation information of the management table stored in the memory 33, the data is rotated before the compression processing. The rotated image data is returned by 90 ° in the direction opposite to the compression process by the rotation processing unit 27, and after the image data is restored, the image data is stored in the image memory 26.
The image is transferred to the printer 24 to form a copy image.

Thus, after detecting a flat line direction having high compression efficiency not only for character data but also for image data, compression is performed after rotating the image data so as to increase the compression efficiency by matching the flat line direction with the compression scanning direction. Therefore, the size of the compressed data can be further reduced, the processing time of the image data can be reduced, the capacity used in the hard disk 30 can be reduced, and the performance of the image processing apparatus and the image forming apparatus can be improved. In addition, since the frequency is calculated every other line when detecting the direction of the flat line, the processing time can be reduced to 比 compared with the case where the frequency is calculated for all the lines.

In each of the specific examples 3 and 4, as a result of detecting a flat line, the same number of lines is used in both the arrow v direction and the arrow w direction, and the compression efficiency is the same in both directions. Compresses the image as it is.

Next, the present invention will be described with reference to FIGS.
This will be described with reference to the embodiment. In this embodiment, an input image is divided into a plurality of regions, and the image is compressed after rotating so that the flat line direction and the compression scanning direction coincide with each other for each of the divided image regions. Since they are the same, the same parts are denoted by the same reference numerals and description thereof will be omitted. The image processing device 53 of the digital copying machine 52 shown in FIG. 15 includes an image memory 26, a rotation processing unit 27, a compression / decompression processing unit 28, a hard disk 30, a frequency counter 47, a flat direction determination unit 48, and a divided image into specified areas. It comprises an image division reconstruction processing unit 54 for reconstructing a processed or divided area.

For example, as shown in FIG. 16, when a document 58 having image data in which the pixel portions 57a and the non-pixel portions 57b are arranged is copied using the sort function, the image area of the document 58 is fixed. It is to divide. That is, the image dividing / reconstructing unit 54 of the image processing device 53 divides the divided region 58a above the line MM 'and the fixed upper and lower half of the divided region 58b below the line MM'.

Then, a flat line direction is selected for each of the divided areas 58a and 58b in the same manner as in the third embodiment. That is, in the upper divided area 58a, the number of lines 1 in the direction of the arrow v is compared with the number of lines 4 in the direction of the arrow w, and
Since the direction of the arrow w is large, it is determined that the direction of the arrow w is the flat direction and the direction of the line with high compression efficiency. On the other hand, in the lower divided region 58b, the number of lines in the direction of arrow v is compared with the number of lines in the direction of arrow w, and the direction of arrow v is large. It is determined that the line direction is high in efficiency.

Therefore, in order to improve the compression efficiency of the image data, the image data of the upper divided area 58a is rotated by 90 °, the flat line direction is made coincident with the compression scan direction, and the data compression efficiency is increased. While the compression processing is performed by the compression / decompression processing unit 28, the image data of the lower divided region 58b is compressed by the compression / decompression processing unit 28 without rotating because the flat line direction matches the compression scanning direction as it is, The compressed data of both divided areas 58a and 58b is stored on the hard disk 30. The rotation information for each divided area is stored in the management table of the memory 33.

Next, in order to print a copied image, the compressed data stored in the hard disk 30 is expanded by the compression / expansion processing unit 28, and then, based on the rotation information in the management table stored in the memory 33, the data is rotated before the compression processing. The image data of the upper divided area 58a is returned by 90 °, and the upper and lower divided areas 58a and 58b are reconstructed by the image division reconstruction processing unit 37 to restore the image data, stored in the image memory 26, and stored in the printer 24. Transfer to form a copied image.

With this configuration, after detecting a flat line direction having high compression efficiency not only for character data but also for image data, the image data is converted so as to match the flat line direction with the compression scanning direction to increase the compression efficiency. Since the compression is performed after the rotation, the size of the compressed data can be further reduced, the processing time of the image data can be reduced, the capacity used in the hard disk 30 can be reduced, and the performance of the image processing apparatus and the image forming apparatus can be improved. Moreover, since the image area is divided and the flat line direction can be detected and the image data can be rotated for each divided area, the flat line direction can be detected more in line with the image content, and the compression efficiency of the image data can be further improved. can get.

Next, the present invention will be described with reference to FIGS.
This will be described with reference to the embodiment. In this embodiment, a line direction having a high compression efficiency is detected by comparing different ratios (pixel variations) of adjacent pixels for each line of image data in a plurality of scanning directions, and this line direction is determined by the image data. The image data is rotated and compressed so that the image data coincides with the compression scanning direction. Since the other components are the same as those in the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted. The image processing device 61 of the digital copying machine 60 shown in FIG.
7, a compression / decompression processing unit 28, a hard disk 30, a difference counter 62, and a flat direction determination unit 63. The difference counter 62 is means for calculating the sum (difference) of the number of adjacent pixels different for each line of the input image data. The flat direction determination unit 63 determines the difference of each line obtained by the difference counter 62 in a predetermined manner. This is a means for comparing with the lower threshold value, calculating the total number of lines below the lower threshold value, and selecting the flat line direction having the largest total value.

For example, as shown in FIG. 18, when a document 68 having image data in which a black pixel portion 64, a gray pixel portion 66, and a non-pixel portion 67 are arranged is copied by using a sort function, first, FIG. As shown in FIG. 19A, the difference counter 62 of the image processing device 61 obtains a difference which is the sum of the number of different adjacent pixels for each line of the image data in the arrow x direction along the compression scanning direction (for example, The value of 1 is determined when adjacent pixels are different from each other such as black and gray or black and white, and 0 when the same is continuous such as white and white or black and black. ), And then the flat direction determination unit 63 calculates a total of 1 of the number of lines whose difference is equal to or smaller than the lower threshold (1). On the other hand, FIG.
As shown in FIG. 9B, the difference counter 62 of the image processing device 61 obtains a difference that is the sum of the number of different adjacent pixels for each line of image data in the arrow y direction perpendicular to the compression scanning direction. In the flat direction determination unit 63, the difference is
The total number of lines equal to or less than the lower threshold value (1) is calculated as 2 and the number of lines in the direction of the arrow x is compared with the number of lines in the direction of the arrow y. , And it is determined that the compression direction is a line direction with high compression efficiency.

Therefore, in order to improve the compression efficiency of the image data, the image data is rotated by 90 ° so that the direction of the flat line is
The data is compressed by the compression / decompression processing unit 28 to increase the data compression efficiency in accordance with the compression scanning direction, and the compressed data is stored in the hard disk 30. The rotation information for each document is stored in the management table of the memory 33.

Next, in order to print a copied image, the compression data stored in the hard disk 30 is expanded by the compression / expansion processing unit 28, and then, based on the rotation information in the management table stored in the memory 33, the data is rotated before the compression processing. The rotated image data is returned by 90 ° in the direction opposite to the compression process by the rotation processing unit 27, and after the image data is restored, the image data is stored in the image memory 26.
The image is transferred to the printer 24 to form a copy image.

With this configuration, after detecting a flat line direction having a high compression efficiency not only for the character data but also for the image data, the image data is compressed so as to match the flat line direction with the compression scanning direction to increase the compression efficiency. Since the compression is performed after the rotation, the size of the compressed data can be further reduced, the processing time of the image data can be reduced, the capacity used in the hard disk 30 can be reduced, and the performance of the image processing apparatus and the image forming apparatus can be improved. Moreover, when detecting the direction of the flat line, the number of adjacent pixels is different, so that the flat line direction can be detected even for an image (multi-valued image) composed of three or more different pixels.

Next, the present invention will be described with reference to FIGS.
This will be described with reference to the embodiment. In this embodiment, the input image is divided into a plurality of regions, and the image is compressed after rotating so that the flat line direction and the compression scanning direction match each other for each of the divided image regions. Since they are the same, the same parts are denoted by the same reference numerals and description thereof will be omitted. The image processing device 71 of the digital copying machine 70 shown in FIG. 20 includes an image memory 26, a rotation processing unit 27, a compression / expansion processing unit 28, a hard disk 30, a difference counter 62, a flat direction determination unit 63, and an image divided into defined areas. It comprises an image division reconstruction processing section 72 for reconstructing a processed or divided area.

As shown in FIG. 21, for example, when a document 77 having image data in which a black pixel portion 73, a gray pixel portion 74, and a non-pixel portion 76 are arranged is copied using a sort function, The image area 77 is divided into fixed areas. That is, the image segmentation reconstruction processing section 72 of the image processing apparatus 71 sets the divided area 77a above the line NN '
It is divided into fixed upper and lower halves of the divided area 77b below the -N 'line.

Then, a flat line direction is selected for each of the divided areas 77a and 77b in the same manner as in the fifth embodiment. That is, in the upper divided area 77a, the number of lines 1 in the arrow x direction and the number of lines 2 in the arrow y direction are compared, and
Since the direction of the arrow y is large, it is determined that the direction of the arrow y is the flat direction and the direction of the line with high compression efficiency. On the other hand, in the lower divided region 77b, the number of lines in the direction of the arrow x is compared with the number of lines in the direction of the arrow 1, and since the direction of the arrow x is large, the direction of the arrow x is flat. It is determined that the line direction is high in efficiency.

Therefore, in order to improve the compression efficiency of the image data, the image data in the upper divided area 77a is rotated by 90 °, and the flat line direction is made coincident with the compression scanning direction to increase the data compression efficiency. While the compression processing is performed by the compression / decompression processing unit 28, the image data of the lower divided area 77b is compressed by the compression / decompression processing unit 28 without rotating because the flat line direction matches the compression scanning direction as it is, The compressed data of both divided areas 77a and 77b is stored in the hard disk 30. The rotation information for each divided area is stored in the management table of the memory 33.

Next, in order to print a copied image, the compression data stored in the hard disk 30 is expanded by the compression / expansion processing unit 28, and then, based on the rotation information of the management table stored in the memory 33, the data is rotated before the compression processing. The image data of the upper divided area 77a is returned by 90 °, and the upper and lower divided areas 77a and 77b are reconstructed by the image division reconstruction processing unit 72 to restore the image data, stored in the image memory 26, and stored in the printer 24. Transfer to form a copied image.

With this configuration, after detecting a flat line direction having a high compression efficiency not only for character data but also for image data, the image data is converted so that the flat line direction and the compression scanning direction are matched to increase the compression efficiency. Since the compression is performed after the rotation, the size of the compressed data can be further reduced, the processing time of the image data can be reduced, the capacity used in the hard disk 30 can be reduced, and the performance of the image processing apparatus and the image forming apparatus can be improved. Moreover, since the image area is divided and the flat line direction can be detected and the image data can be rotated for each divided area, the flat line direction can be detected more in line with the image content, and the compression efficiency of the image data can be further improved. can get. Furthermore, even with image data composed of multi-valued images, more efficient image compression is possible.

It should be noted that the present invention is not limited to the above-described embodiment, and can be changed without departing from the spirit of the present invention. The image can be divided into left, right, and many, and the case where image contents are read and divided is completely arbitrary. The color of each pixel of the image is not limited, and the number of pixels of the multi-valued image is arbitrary. Further, when detecting the direction of the flat line, the scanning direction of the line is free, and the scanning is not limited to two directions, but may be arbitrary, such as scanning from many directions.

[0064]

As described above, according to the present invention, the compression processing is performed after rotating in the direction of high compression efficiency in accordance with the content of the image data. The data processing time required for inputting / outputting compressed data can be shortened, the capacity of the storage medium used for the compressed data can be reduced, and the performance of the image processing apparatus and the image forming apparatus can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a system configuration of a digital copying machine according to the principle of the present invention.

FIG. 2 is a schematic configuration diagram showing a system configuration of the digital copying machine according to the first embodiment of the present invention.

FIG. 3 is a flowchart illustrating a process of compressing image data according to the first embodiment of the present invention.

4A and 4B show handling of image data according to the first embodiment of the present invention. FIG. 4A shows a case where the text direction and the compression direction match, and FIG. 4B shows a case where the text direction and the compression direction are perpendicular. It is a schematic explanatory view showing a case.

FIG. 5 is a schematic explanatory diagram showing a part of the contents of a management table stored in a memory according to the first embodiment of this invention.

FIG. 6 is a schematic configuration diagram showing a system configuration of a digital copying machine according to a second embodiment of the present invention.

FIG. 7 is a schematic explanatory diagram illustrating a document according to Example 1 of the second embodiment of the present invention.

FIG. 8 is a schematic explanatory diagram showing a document of a specific example 2 of the second embodiment of the present invention.

FIG. 9 is a schematic explanatory diagram showing a part of the contents of a management table stored in a memory according to the second embodiment of this invention.

FIG. 10 is a schematic configuration diagram showing a system configuration of a digital copying machine according to a third embodiment of the present invention.

FIG. 11 is a schematic explanatory view showing a document of Example 3 of the third embodiment of the present invention.

12A and 12B show a detection operation in the flat line direction according to the third example of the third embodiment of the present invention. FIG. 12A shows the case where the frequency of each line in the compression scanning direction is obtained, and FIG. FIG. 5 is a schematic explanatory diagram showing a case where a frequency is obtained for each line in a scanning direction and a vertical direction.

FIG. 13 is a schematic explanatory diagram showing a document of Example 4 of the third embodiment of the present invention.

14A and 14B show a detection operation in the flat line direction according to Example 4 of the third embodiment of the present invention. FIG. 14A shows the case where the frequency of every other line in the compression scanning direction is obtained, and FIG. FIG. 7 is a schematic explanatory diagram showing a case where the frequency is obtained every other line in the compression scanning direction and the vertical direction.

FIG. 15 is a schematic configuration diagram showing a system configuration of a digital copying machine according to a fourth embodiment of the present invention.

FIG. 16 is a schematic explanatory view showing a document according to a fourth embodiment of the present invention.

FIG. 17 is a schematic configuration diagram showing a system configuration of a digital copying machine according to a fifth embodiment of the present invention.

FIG. 18 is a schematic explanatory view showing a document according to a fifth embodiment of the present invention.

19A and 19B show a detection operation in the flat line direction according to the fifth embodiment of the present invention, wherein FIG. 19A shows a case where a difference for each line in the compression scanning direction is obtained, and FIG. FIG. 9 is a schematic explanatory diagram showing a case where a difference for each line in a direction is obtained.

FIG. 20 is a schematic configuration diagram showing a system configuration of a digital copying machine according to a sixth embodiment of the present invention.

FIG. 21 is a schematic explanatory view showing a document according to a sixth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 20 ... Digital copying machine 21 ... Common bus 22 ... CPU 23 ... Scanner 24 ... Printer 25 ... Image processing device 26 ... Image memory 27 ... Rotation processing unit 28 ... Compression / decompression processing unit 30 ... Hard disk 31 ... Character image judgment unit 32 ... Text Direction determination unit 33 ... Memory

Continued on front page F-term (reference) 2C087 BB10 BC02 BC05 BC14 BD24 BD40 CA13 2H027 EC19 EE08 FD02 FD08 5C078 CA27 CA31 DA01 DA02 DA21 DB16 9A001 BB03 EE02 HH22 HH24 HH27 HH34 JJ35 KK31 KK42

Claims (22)

[Claims] An image input unit for inputting image data obtained from an original image; a direction detecting unit for detecting an efficient compression direction of the original image from the image data input by the image input unit; A rotation unit configured to rotate the image data so that an array of the image data matches the efficient compression direction; a compression unit configured to compress the rotation data after the rotation processing by the rotation unit; and a compression unit formed by the compression unit. Image storing means for storing compressed data stored in the storage means, and decompressing means for decompressing and rotating the compressed data stored in the data storing means to decompress the image data. Processing equipment. 2. An image input means for inputting image data obtained from an original image, a direction detecting means for detecting an efficient compression direction of the original image from the image data input by the image input means, A rotation unit configured to rotate the image data so that an array of the image data matches the efficient compression direction; a compression unit configured to compress the rotation data after the rotation processing by the rotation unit; and a compression unit formed by the compression unit. Data storage means for storing compressed data to be stored, decompression means for decompressing and rotating the compressed data stored in the data storage means to restore the image data, and An image forming apparatus comprising: an image output unit that forms a print image based on image data. 3. Image input means for inputting image data obtained from a document image, image dividing means for dividing the image data input by the image input means into arbitrary regions of the document image, Direction detecting means for detecting an efficient compression direction of the divided data for each of the areas divided by the dividing means; and rotation for rotating the divided data so that the arrangement of the divided data matches the efficient compression direction. Means, compression means for compressing the divided rotation data of the rotation processing by the rotation means, data storage means for storing the divided compressed data formed by the compression means, and the division stored in the data storage means An image processing apparatus comprising: a decompression unit for decompressing and rotating compressed data to decompress the divided data. 4. Image input means for inputting image data obtained from a document image, image dividing means for dividing the image data input by the image input means into arbitrary regions of the document image, Direction detecting means for detecting an efficient compression direction of the divided data for each of the areas divided by the dividing means; and rotation for rotating the divided data so that the arrangement of the divided data matches the efficient compression direction. Means, compression means for compressing the divided rotation data of the rotation processing by the rotation means, data storage means for storing the divided compressed data formed by the compression means, and the division stored in the data storage means Restoring means for decompressing and rotating the compressed data to restore the divided data; and An image forming apparatus comprising: reconstructing means for reconstructing image data; and image output means for forming a print image based on the image data reconstructed by the reconstructing means. 5. Image input means for inputting image data obtained from a document image, character determination means for determining whether the image data input by the image input means is character data, and text of the character data Text direction determining means for determining a direction, rotating means for rotating the image data so that the arrangement of the character data matches the text direction, and compressing means for compressing the rotated data after the rotating processing by the rotating means. Data storage means for storing compressed data formed by the compression means; and decompression means for decompressing and rotating the compressed data stored in the data storage means to restore the image data. An image processing apparatus comprising: 6. Image input means for inputting image data obtained from a document image, character determination means for determining whether the image data input by the image input means is character data, and text of the character data Text direction determining means for determining a direction, rotating means for rotating the image data so that the arrangement of the character data matches the text direction, and compressing means for compressing the rotated data after the rotating processing by the rotating means. Data storage means for storing compressed data formed by the compression means; decompression means for decompressing and rotating the compressed data stored in the data storage means to restore the image data; An image output unit for forming a print image based on the image data restored by the restoration unit. . 7. Image input means for inputting image data obtained from a document image, image dividing means for dividing the image data input by the image input means into fixed regions for each area of the document image, Character determining means for determining whether or not the divided data for each area divided by the image dividing means is divided character data; text direction determining means for determining the text direction of the divided character data; and an array of the divided character data Means for rotating the divided data so as to match the sentence direction, compression means for compressing the divided rotation data after the rotation processing by the rotating means, and storing the divided compressed data formed by the compression means. Data storage means for performing expansion processing and rotation processing on the divided compressed data stored in the data storage means to restore the divided data. An image processing apparatus comprising: 8. An image inputting means for inputting image data obtained from a document image, an image dividing means for dividing the image data inputted by the image inputting means into fixed regions for each area of the document image, Character determining means for determining whether or not the divided data for each area divided by the image dividing means is divided character data; text direction determining means for determining the text direction of the divided character data; and an array of the divided character data Means for rotating the divided data so as to match the sentence direction, compression means for compressing the divided rotation data after the rotation processing by the rotating means, and storing the divided compressed data formed by the compression means. Data storage means for performing expansion processing and rotation processing on the divided compressed data stored in the data storage means to restore the divided data. Restoring means, reconstructing means for reconstructing the divided data restored by the restoring means into the image data, and image output means for forming a print image based on the image data reconstructed by the reconstructing means An image forming apparatus comprising: 9. An image input means for inputting image data obtained from a document image, a character area extracting means for extracting a character image area from the image data input by the image input means, and a character area extracting means. An image dividing unit for dividing the extracted character image region; a text direction determining unit for determining a text direction of the divided character data of the character image region divided by the image dividing device; and an array of the divided character data. A rotating means for rotating the divided data so as to match the sentence direction; a compressing means for compressing the divided rotated character data after the rotating processing by the rotating means; and storing the divided compressed data formed by the compressing means. Data storage means for expanding and compressing the divided compressed data stored in the data storage means and rotating the divided compressed data. An image processing apparatus, comprising: restoring means for restoring split character data. 10. An image input means for inputting image data obtained from a document image, a character area extracting means for extracting a character image area from the image data input by the image input means, and a character area extracting means. An image dividing unit for dividing the extracted character image region; a text direction determining unit for determining a text direction of the divided character data of the character image region divided by the image dividing device; and an array of the divided character data. A rotating means for rotating the divided data so as to match the sentence direction; a compressing means for compressing the divided rotated character data after the rotating processing by the rotating means; and storing the divided compressed data formed by the compressing means. Data storage means for performing expansion processing and rotation processing on the divided compressed data stored in the data storage means, Restoring means for restoring the divided character data, reconstructing means for returning the divided character data restored by the restoring means to the character image area of the image data to reconstruct the image data, An image output unit configured to form a print image based on the reconstructed image data. 11. An image input means for inputting image data obtained from a document image, and a plurality of scan data obtained by scanning the document image in a plurality of directions from the image data input by the image input means. Scanning data extracting means for extracting, and for each of the plurality of scanning data obtained by the scanning data extracting means, extracting a data frequency in a line along the scanning direction, wherein the extracted data frequency is a predetermined upper threshold. Flat line direction discriminating means for summing the number of upper lines and the number of lower lines for which the data frequency is equal to or less than a predetermined lower threshold, and judging a predetermined line direction in which the total number of total lines is maximized, The image data is arranged such that the arrangement of the image data matches the predetermined line direction determined by the flat line direction determination unit. Rotation means for performing rotation processing, compression means for compressing rotation data after rotation processing by the rotation means, data storage means for storing compressed data formed by the compression means, and data stored in the data storage means A decompression unit for decompressing and rotating the compressed data to decompress the image data. 12. The method according to claim 11, wherein the data frequency is extracted from sampling lines formed by sampling at predetermined intervals from all the lines along the scanning direction.
An image processing apparatus according to claim 1. 13. An image input means for inputting image data obtained from a document image, and a plurality of scan data obtained by scanning the document image in a plurality of directions from the image data input by the image input means. Scanning data extracting means for extracting, and for each of the plurality of scanning data obtained by the scanning data extracting means, extracting a data frequency in a line along the scanning direction, wherein the extracted data frequency is a predetermined upper threshold. Flat line direction discriminating means for summing the number of upper lines and the number of lower lines for which the data frequency is equal to or less than a predetermined lower threshold, and judging a predetermined line direction in which the total number of total lines is maximized, The image data is arranged such that the arrangement of the image data matches the predetermined line direction determined by the flat line direction determination unit. Rotation means for performing rotation processing, compression means for compressing rotation data after rotation processing by the rotation means, data storage means for storing compressed data formed by the compression means, and data stored in the data storage means Restoration means for restoring the image data by expanding and rotating the compressed data, and image output means for forming a print image based on the image data restored by the restoration means. Image forming apparatus. 14. The data frequency is extracted from sampling lines formed by sampling at predetermined intervals from all lines along the scanning direction.
An image forming apparatus according to claim 1. 15. An image input means for inputting image data obtained from a document image, an image dividing means for dividing the image data input by the image input means into arbitrary regions of the document image, Scanning data extracting means for extracting a plurality of divided scan data obtained by scanning an arbitrary area of the document image in a plurality of directions from the divided data for each area divided by the dividing means; For each of the plurality of obtained divided scan data, a divided data frequency in a divided line along the scanning direction is extracted, and the extracted divided data frequency is equal to or greater than a predetermined upper threshold, and The number of divided lower lines whose data frequency is equal to or less than a predetermined lower threshold value is summed up, and a predetermined divided line in which the total number of divided lines becomes the maximum is obtained. Flat line direction determining means for determining a line direction; rotating means for rotating the divided data so that the arrangement of the divided data matches the predetermined divided line direction determined by the flat line direction determining means; Compression means for compressing the divided rotation data after the rotation processing by the rotation means, data storage means for storing the divided compression data formed by the compression means, and the divided compression data stored in the data storage means An image processing apparatus comprising: a decompression unit that performs decompression processing and rotation processing to recover the divided data. 16. The image processing apparatus according to claim 15, wherein the division data frequency is extracted for sampling division lines obtained by sampling at predetermined intervals from all division lines along the scanning direction. 17. An image input means for inputting image data obtained from a document image, an image dividing means for dividing the image data input by the image input means into arbitrary regions of the document image, Scanning data extracting means for extracting a plurality of divided scan data obtained by scanning an arbitrary area of the document image in a plurality of directions from the divided data for each area divided by the dividing means; For each of the plurality of obtained divided scan data, a divided data frequency in a divided line along the scanning direction is extracted, and the extracted divided data frequency is equal to or greater than a predetermined upper threshold, and The number of divided lower lines whose data frequency is equal to or less than a predetermined lower threshold value is summed up, and a predetermined divided line in which the total number of divided lines becomes the maximum is obtained. Flat line direction determining means for determining a line direction; rotating means for rotating the divided data so that the arrangement of the divided data matches the predetermined divided line direction determined by the flat line direction determining means; Compression means for compressing the divided rotation data after the rotation processing by the rotation means, data storage means for storing the divided compression data formed by the compression means, and the divided compression data stored in the data storage means Restoring means for performing decompression processing and rotation processing to restore the divided data, reconstructing means for reconstructing the divided data restored by the restoring means into the image data, and reconstructing by the reconstructing means An image forming apparatus comprising: an image output unit that forms a print image based on the image data. 18. The image forming apparatus according to claim 17, wherein the division data frequency is extracted from sampling division lines obtained by sampling at predetermined intervals from all division lines along the scanning direction. 19. An image input means for inputting image data obtained from a document image, and a plurality of scan data obtained by scanning the document image in a plurality of directions from the image data input by the image input means. Scanning data extracting means to be extracted, and for each of the plurality of scanning data obtained by the scanning data extracting means, the number of discontinuities with adjacent pixels in a line along the scanning direction is summed, Flat line direction discriminating means for judging a predetermined line direction that minimizes the number; rotating processing of the image data so that the arrangement of the image data matches the predetermined line direction judged by the flat line direction judging means Rotating means for performing rotation processing, compression means for compressing rotation data after rotation processing by the rotating means, and compression means formed by the compression means. Image storage means for storing compressed data to be stored, and decompression means for decompressing and rotating the compressed data stored in the data storage means to decompress the image data. Processing equipment. 20. Image input means for inputting image data obtained from a document image, and a plurality of scan data obtained by scanning the document image in a plurality of directions from the image data input by the image input means. Scanning data extraction means to be extracted; and for each of the plurality of scanning data obtained by the scanning data extraction means, a sum of discontinuous values of adjacent pixels in a line along the scanning direction, Flat line direction determining means for determining a predetermined line direction having a minimum value; and rotating the image data so that the arrangement of the image data matches the predetermined line direction determined by the flat line direction determining means. Rotating means for performing rotation processing, compression means for compressing rotation data after rotation processing by the rotating means, and compression means formed by the compression means. Data storage means for storing compressed data to be restored, decompression means for decompressing and rotating the compressed data stored in the data storage means to restore the image data, and An image forming apparatus comprising: an image output unit that forms a print image based on image data. 21. Image input means for inputting image data obtained from a document image; image dividing means for dividing the image data input by the image input means into arbitrary regions of the document image; Scanning data extracting means for extracting a plurality of divided scan data obtained by scanning an arbitrary area of the document image in a plurality of directions from the divided data for each area divided by the dividing means; For each of the plurality of obtained divided scan data, the number of division discontinuities with adjacent pixels in the division line along the scanning direction is summed, and a predetermined division line direction in which the sum of the division total discontinuity is minimized Flat line direction determining means for determining whether the predetermined divided line is determined by the flat line direction determining means. Rotation means for rotating the divided data so as to match the direction, compression means for compressing the divided rotation data after the rotation processing by the rotation means, and data storage for storing the divided compressed data formed by the compression means. An image processing apparatus comprising: a memory means; and a decompression means for decompressing and rotating the divided compressed data stored in the data storage means to decompress the divided data. 22. Image input means for inputting image data obtained from a document image; image dividing means for dividing the image data input by the image input means into arbitrary regions of the document image; Scanning data extracting means for extracting a plurality of divided scan data obtained by scanning an arbitrary area of the document image in a plurality of directions from the divided data for each area divided by the dividing means; For each of the plurality of obtained divided scan data, the number of division discontinuities with adjacent pixels in the division line along the scanning direction is summed, and a predetermined division line direction in which the sum of the division total discontinuity is minimized Flat line direction determining means for determining whether the predetermined divided line is determined by the flat line direction determining means. Rotation means for rotating the divided data so as to match the direction, compression means for compressing the divided rotation data after the rotation processing by the rotation means, and data storage for storing the divided compressed data formed by the compression means. Means for decompressing and compressing the divided compressed data stored in the data storage means to restore the divided data, and the divided data restored by the restoration means to the image data. An image forming apparatus comprising: reconstructing means for reconstructing; and image output means for forming a print image based on the image data reconstructed by the reconstructing means.