JP2001157063A - Image data encoding and decoding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image data encoding and decoding device which detects an abnormal image occurring due to wrong encodings (coding errors) at the decoding of encoded image data and which informs a user of the detection of the abnormal images when detected. SOLUTION: A memory control part 805 prepares reduced image data obtained by reducing image data. When a decoding part 804 decodes the encoded image data, a data comparing part 802 accesses to a pixel having an address, where the part 805 prepares the reduced image data, to compare it with the values of the pixels of the reduced image data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image data encoding / decoding apparatus, and more particularly to a method of inputting image data as digital data to a storage means such as a memory or a hard disk, and repeatedly outputting the image data stored in the storage means. The present invention relates to an image data encoding / decoding device included in an image forming system such as a copying machine that can be used efficiently.

[0002]

2. Description of the Related Art Conventionally, some copying machines store image data once read by a scanner on a hard disk or the like. The copier eliminates the need to scan the original again by extracting the image data stored on the hard disk or the like.

FIG. 1 is a configuration diagram showing the internal configuration of a copying machine that handles image data as digital signals. According to FIG. 1, this copier includes a scanner 101, an A / D converter 10
2. The image processing unit 103 includes an image storage unit 104, an image output unit 105, an operation unit 106, and a main control unit 107.

The copying machine scans a document with a scanner 101 and converts the document into image data. The image data is converted from an analog signal to a digital signal in the A / D converter 102.

Next, an image processing section 103 performs image processing such as gamma conversion and image quality correction on the image data. The image data that has been subjected to image processing by the image processing unit 103 is once stored in the image storage unit 104. The image output unit 105 reads out the image data stored in the image storage unit 104 and prints the image data on a paper for each pixel.

At this time, the scanner 101 and the A / D converter 1
02, the image processing unit 103, the image storage unit 104, and the image output unit 105 receive a user instruction via the operation unit 106 and the main control unit 107 as control signals,
Processing is performed under the control of the main control unit 107.

FIG. 2 is a configuration diagram showing the internal configuration of the image storage unit 104. According to FIG. 2, the image storage unit 104
It comprises a memory 201, an encoding unit 202, a decoding unit 203, a memory control unit 204, a hard disk I / F unit 205, a hard disk 206, and a main control unit 107. Further, the encoding unit 202, the decoding unit 203, and the memory control unit 204 exist in the encoding / decoding IC 207.

The image data stored in the memory 201 in the image storage unit 104 from the image processing unit 103 is transmitted to the main control unit 1
Under the control of 07, access is made by the memory control unit 204 in the encoding / decoding IC 207.

As a result, the image data is transferred to the encoding unit 202 line by line. Next, the encoding unit 202 encodes (compresses) the image data.
After that, the data is transferred to the hard disk I / F unit 205.

The hard disk I / F unit 205 controls the hard disk 206 by outputting a control signal corresponding to the hard disk 206, and stores the transferred image data in the hard disk 206.

When the encoded image data (coded data) in the hard disk 206 is printed by the image output unit 105, the encoded image data (coded data) in the hard disk 206 is controlled under the control of the main control unit 107. )
Is transmitted to the decryption unit 20 via the hard disk I / F unit 205.
3 is output.

[0012] The decoding unit 203 to which the encoded image data (coded data) is input decodes the code. The decoded image data is written to an address on the memory 201 updated by the memory control unit 204.

After storing one page of image data in the memory 201, the main control unit 107
04 is set to output the image data stored in the memory 201 to the image output unit 105.

[0014] The memory control unit 204 having received this setting,
The address of the image data is sequentially updated, the image data on the memory 201 is read, and the image data is output to the image output unit 105. Thereby, the image output unit 105
This image data can be printed on paper.

As an encoding / decoding system used for the above-mentioned encoding and decoding, an arithmetic encoding system is often used. This arithmetic coding method is a method in which the appearance probability of a pixel of interest to be coded is obtained from the conditional probability of the state of a pixel (reference pixel) around the pixel of interest, and encoding is performed using the value of this probability.

For example, when the template shown in FIG. 4 is used, the probability that the target pixel X is black or white is determined by the pixels A, B, C, D, and E shown in FIG. From the conditional probability of the combination of

In the case of encoding the ninth pixel on the second line in the image data shown in FIG. 3, the template shown in FIG. 4 is as shown in FIG.

As described above, the above-mentioned arithmetic coding method does not use a code for line synchronization in the middle of coding one page of an image. Therefore, if a code error occurs in the middle of encoding, images subsequent to the pixel in which the code error occurs become completely random.

When the image data shown in FIG. 6 is encoded,
If a code error (code error) has occurred in the image data on the m-th line, the image becomes random from the m-th line as shown in FIG. turn into.

As described above, it has been pointed out that when a code error (code error) occurs during encoding by the arithmetic coding method, an image becomes a random noise.

As a prior art relating to a code error, there is one disclosed in Japanese Patent Application Laid-Open No. Hei 10-200416.

In this prior art, after the transmission of fixed byte code data is completed, an encoding agenda at the time of completion of the encoding of the current pixel is transmitted, and the decoding device transmits the encoding augend transmitted from the encoding device to the current pixel. A code error (code error) is detected by comparing with the decoding agend used in the encoding of (1).

According to the above-mentioned prior art, if there is a code error (code error) generated at the time of encoding, it can be detected.

[0024]

However, according to the above-mentioned prior art, for example, a code error (code error) due to a cause other than a code error (code error) generated at the time of decoding, such as noise to a decoding unit, is caused. ) Cannot be detected if present. Therefore, it cannot be said that this prior art shows a complete countermeasure for the above problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an image data encoding / decoding apparatus for detecting an abnormal image caused by a code error (code error) when decoding encoded image data. The purpose is to provide.
It is another object of the present invention to provide an image data encoding / decoding device that notifies a user when an abnormal image is detected.

[0026]

To achieve the above object, according to the first aspect of the present invention, there is provided first storage means for storing digital image data, and code data obtained by encoding the image data. Second storage means, reduced image generation means for generating reduced image data thinned out every n pixels in the horizontal direction of image data, and every m pixels in the vertical direction of image data, and reduced image data generated by the reduced image generation means The decoded image comparison means for comparing the image data with the image data obtained by decoding the code data stored by the second storage means, and the result of the comparison by the decoded image comparison means is that the reduced image data and the image data are different. Code error discriminating means for discriminating whether or not there is the decoded data comparing means, wherein the decoded image comparing means includes:
This is for comparing the reduced image data with pixels every n pixels in the horizontal direction and every m pixels in the vertical direction, and the code error determining means has a different value among the pixels compared by the decoded image comparing means. , It is determined that there is a code error in the code data.

According to a second aspect of the present invention, in the device of the first aspect, the reduced image data is stored by a second storage means.

According to a third aspect of the present invention, in the device of the first aspect, the reduced image data is stored by a first storage means.

According to a fourth aspect of the present invention, in the apparatus according to any one of the first to third aspects, when the code error discriminating means determines that there is a code error in the code data, the code error is determined. And a display unit for displaying that there is a conversion error.

[0030]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 8 shows an embodiment of the present invention.
3 is a configuration diagram showing an internal configuration of an image storage unit 104 of the copying machine shown in FIG. According to FIG. 8, the image storage unit 104 includes a memory 801, a data comparison unit 802, an encoding unit 803, a decoding unit 804, a memory control unit 805, and a hard disk I / O.
An F unit 806 and a hard disk 807 are provided.

The data comparing unit 802, the encoding unit 803, the decoding unit 804, and the memory control unit 805 exist in the encoding / decoding IC 808.

The memory 801 stores the image data input from the image processing unit. The memory 801 includes a decoding unit 80
4 stores the decoded image data. Memory 80
Numeral 1 stores reduced image data obtained by reducing image data.

The data comparing section 802 compares the reduced image data with the image data decoded by the decoding section 804. The data comparison unit 802 compares the reduced image data with the encoded image data,
An error bit is set in the status register in the data comparison unit 802.

The encoding unit 803 encodes the image data stored in the memory 801 and input from the image processing unit. The decoding unit 804 decodes coded image data (coded data) stored in the hard disk 807.

The memory control unit 805 reduces image data input from the image processing unit stored in the memory 801. The memory control unit 805 stores the image data at a predetermined address.

The hard disk I / F unit 806 stores encoded image data (coded data) and reduced image data on the hard disk 807. The hard disk I / F unit 806 extracts encoded image data (coded data) and reduced image data from the hard disk 807 and inputs them to the encoding / decoding IC 808.

The main control unit 107 has a hard disk I / F
Unit 806, hard disk 807, and encoding / decoding I
By controlling C808, the operation of the image storage unit 104 is controlled.

The operation of the image storage unit 104 in the image data encoding / decoding apparatus according to the embodiment of the present invention for decoding and storing image data will be described with reference to FIG.

The main control unit 107 controls the image processing unit 103 to
The image data is input to the image storage unit 104. The image storage unit 104 stores the image data input from the image processing unit 103 in a normal image area in the memory 801.

The main control unit 107 includes an encoding / decoding IC 808
Is set to a mode for handling reduced images (step S90).
1). In the mode for handling the reduced image, the image data stored in the memory 801 is reduced and the hard disk 807 is used.
When the image data is stored, the encoding unit 803 does not encode the reduced image data (step S902).

That is, the main control unit 107 sets the encoding unit 803 in the encoding / decoding IC 808 to the encoding off state,
The reduced image data is stored in the hard disk drive 80 by the memory control unit 805 using the reduced data as it is.
7 is stored. As a result, the reduced image data includes
No code error (code error) occurs.

After the above setting, the main control unit 107 sends the reduced image data to the encoding / decoding IC 808 and the hard disk I / F unit 806.
Set to start storing. After this setting, the image storage unit 104 stores the reduced image data in the hard disk 807
Then, the operation of storing the data in the storage device is started (step S903).

The memory control unit 805 accesses the pixels every ten pixels in the horizontal direction of the image data. That is, the memory control unit 805 determines that the first pixel in the horizontal direction of the image data, the eleventh pixel, the twenty-first pixel,...
to access.

The memory control unit 805 accesses the pixels every 10 lines in the vertical direction of the image data.
That is, the memory control unit 805 accesses the first line of the image data as the first pixel, the eleventh pixel, the twenty-first pixel,.
Line 1 is the first pixel in the horizontal direction, the eleventh pixel,
The first pixel is accessed.

The memory control unit 805 can generate reduced image data reduced to one tenth by repeating the above operation.

As described above, the pixels accessed by the memory control unit 805 are sequentially transferred to the hard disk 807 (step S904).

The main control unit 107 checks the status of the transfer (step S905). If the transfer of the pixel has not been completed (step S905 / NO), step S905
Returning to 904, the memory control unit 805 accesses a pixel in the image data and transfers the pixel to the hard disk.

When the transfer of the pixels is completed and the reduced image data is stored in the hard disk 807 (step S
905 / YES), the main control unit 107
For 808, the mode is set to a mode for handling a normal 1: 1 image (step S906).

By setting the mode for handling the normal normal-size image, the encoding unit 803 performs encoding on the input image data (encoding ON setting) (step S907). .

After this setting, the main control unit 107 sets the encoding / decoding IC 808 and the hard disk I / F 806 so as to start storing the image data in the hard disk 807 (hard disk storage start) (step S908). .

As a result, the image data stored in the memory is accessed by the memory control unit 805 and input to the encoding unit 803. Next, the encoding unit 803 encodes the input image data. Then, the encoded image data (coded data) is transferred to the hard disk 807 via the hard disk I / F unit 806 and stored (step S909).

The main control unit 107 checks the status of the transfer (step S910). If all of the image data stored in the memory has not been transferred to the hard disk 807 (step S910 / NO), step S910
Returning to step 909, the memory control unit 805 accesses the image data and inputs the accessed pixel to the encoding unit 803.

If all the image data stored in the memory has been transferred to the hard disk 807 (step S910 / YES), the main control unit 107 ends the processing.

The operation of the image storage unit shown in FIG. 8 according to the embodiment of the present invention for judging whether the decoded image data is normal when decoding the code data is shown in FIG.
This will be described with reference to FIG.

The main control unit 107 includes an encoding / decoding IC 808
Is set to transfer the reduced image data to the memory 801 (step S1001). The setting to instruct to transfer the reduced image data to the memory 801 is as follows.
The decoding unit 804 in the encoding / decoding 808 is set not to decode the reduced image data input to the encoding / decoding IC 808 via the hard disk I / F unit 806 (decoding off setting) (step S1002). Thus, the reduced image data is not decoded by the decoding unit 804, and is stored in the memory 801 as it is.

After the above setting, the main control unit 107 sets the encoding / decoding IC 808 and the hard disk I / F unit 806
In step S1003, a setting is made to start transferring the reduced image data to the memory 801 (start reading the hard disk).

With this setting, the hard disk I / F unit 806 reads the reduced image data stored in the hard disk 807 and inputs the data to the encoding / decoding IC 808.
The encoding / decoding IC 808 does not perform any processing on the reduced image data, transfers it to the memory 801 and expands it (step S1004).

The main control unit 107 checks the status of the transfer end (step S1005). To memory 801
If not all reduced image data has been transferred (step S1005 / NO), the process returns to step S1004,
The encoding / decoding IC 808 expands the remaining reduced image data in the memory 801.

If all the reduced image data has been transferred to the memory 801 (step S1005 / YE)
S), the main control unit 107 controls the hard disk I / F unit 80
6 and the encoding / decoding IC 808 so as to transfer normal 1: 1 image data to the memory 801 (step S1006).

The normal 1: 1 image data is stored in the memory 801.
The setting to transfer the image data is made such that the decoding unit 804 in the encoding / decoding IC 808 decodes the input image data.

After this setting, the main control unit 107 controls the encoding / decoding IC 808 and the hard disk I / F unit 806
Is set to start transferring the image data stored in the hard disk to the memory 801 (start reading the hard disk) (step S100).
8).

With this setting, the hard disk I / F unit 806 reads the encoded image data stored in the hard disk 807 and inputs it to the encoding / decoding IC 808.

The decoding unit 804 in the encoding / decoding IC 808
Decodes the encoded image data. Decoding unit 8
04 is stored in the memory controller 8
05, it is stored at a predetermined address on the memory 801 (step S1009).

At this time, the data comparing section 802 compares the reduced image data with the image data decoded by the decoding section 804 (step S1010).

As described above, the image data is obtained by reducing the image data input from the image processing unit 103. As described above, the memory control unit 805 outputs the reduced image data every 10 pixels (1 pixel) in the horizontal direction of the image data.
Pixel, eleventh pixel, twenty-first pixel ...
..) And accesses every ten lines in the vertical direction of the image data (first line, eleventh line, twenty-first line,...)
・) Created by accessing.

Therefore, the data comparing section 802 is connected to the decoding section 8
04, the image data decoded is accessed in the same manner as when the reduced image data is created, and by comparing this pixel with the corresponding pixel on the reduced image data, It is determined whether the image data is equal to the encoded and decoded image data.

If there is a code error (code error) in the coded image data (code data), the image data is random noise-like on the rear side of the code error (code error) as shown in FIG. become.

That is, the image data behind the code error (code error) is completely different from the original image data as shown in FIGS. for that reason,
If there is a code error (code error) in the code data, the pixel of the reduced image data and the pixel sampled by the same method as that for generating the reduced image data from the decoded image data are different. Become.

Therefore, the data comparing section 802 determines whether or not there is a code error (code error) in the code data by comparing the reduced image data with the image data decoded by the decoding section 804. Will be possible.

When the data comparing section 802 determines that there is a code error (code error) in the image data (coded data) encoded by the encoding section 803, the data comparing section 802 stores the data in the status register in the data comparing section 802. , Set an error bit.

The main control unit 107 checks the status of the transfer end (step S1011). Hard disk 8
07 has not been transferred to the memory 801 (step S1011 / N).
O), returning to step S1009, the main control unit 107
The remaining image data is transferred to the memory 801.

When all the image data stored in the hard disk 807 has been transferred to the memory 801 (step S1011 / YES), the main control unit 107 checks whether the error bit of the status register in the data comparison unit 802 is set. It is confirmed (whether a code error has been detected) (step S1012).

When the error bit of the status register in the data comparison unit 802 has not been set (step S
(1012 / NO), the image storage unit 104 ends the processing.

When the error bit of the status register in the data comparison unit 802 is set (step S101)
2 / YES), the main control unit 107 causes a display unit (not shown) to display a notification that there is a code error as shown in FIG.

According to the embodiment of the present invention, even when a code error (code error) occurs at the time of coding / decoding of image data and an abnormal image is formed, the image data coding / decoding apparatus can be used. , It is possible to determine the situation.

Further, at the time of encoding / decoding the image data, the user can confirm that a code error (code error) has occurred and the image has become abnormal. Therefore, the user does not need to distribute the image that has become abnormal due to the occurrence of the code and without knowing that the image has become abnormal.

The reduced image data may be stored in the memory 801 instead of the hard disk 807. According to this, the reduced image data created by the memory control unit 805 is transmitted to the hard disk 80 via the encoding / decoding IC 808 and the hard disk I / F unit 806.
7 and decode the coded data, there is no need to develop the data in the memory via the hard disk I / F unit 806 and the coding / decoding IC 808. Therefore, since the processing procedure is omitted, the processing speed is improved.

FIG. 12 shows a data area of the memory 801. As shown in FIG. 12, the memory 801 includes a normal image area for storing image data and a reduced image area for storing reduced image data.

As described above, the memory 801 needs to have a reduced image area for storing the reduced image data. Alternatively, the memory 801 needs an extra area for storing reduced image data.

However, as in the case of the reduced image data, 10
When the image data is reduced to one-hundredth, the reduced image data has a data amount of 1/100 of the image data. Therefore, the above-mentioned extra area is small.

[0082]

As is apparent from the above description, according to the first aspect of the present invention, the first storage means for storing digital image data and the second storage means for storing code data obtained by encoding image data. 2, a reduced image generating means for generating reduced image data thinned out every n pixels in the horizontal direction of the image data and every m pixels in the vertical direction of the image data, and a reduced image generated by the reduced image generating means Data and the second
A decoded image comparing means for comparing the decoded image data with the decoded image data stored by the storage means, and a code error for determining whether the reduced image data is different from the image data as a result of the comparison by the decoded image comparing means. And a decoded image comparison unit, wherein the decoded image comparison unit decodes the encoded data stored in the second storage unit, and sets the reduced image data to n-pixels in the horizontal direction and m-pixels in the vertical direction. The image data is compared, and the code error determination means determines that there is a code error in the code data if any of the pixels compared by the decoded image comparison means has a different value. Accordingly, the occurrence of an abnormal image can be easily detected by a simple method.

According to the second aspect of the present invention, in the apparatus of the first aspect, since the reduced image data is stored by the second storage means, the occurrence of an abnormal image can be reduced by a simple method. , And can be easily detected.

According to the third aspect of the present invention, in the apparatus of the first aspect, since the reduced image data is stored in the first storage means, the processing procedure is reduced, and the overall productivity is reduced. Can be improved.

According to a fourth aspect of the present invention, in the apparatus according to any one of the first to third aspects, when the code error determining means determines that there is a code error in the code data, In addition, by further providing a display unit for displaying that there is an encoding error, it becomes possible for the user to know that the image is an abnormal image.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram illustrating an internal configuration of an image storage unit according to the related art.

FIG. 3 is an enlarged view of image data according to the embodiment of the present invention.

FIG. 4 is a diagram showing an example of a template of an arithmetic coding scheme according to the embodiment of the present invention.

FIG. 5 is a diagram in which the template shown in FIG. 4 is applied to the image data shown in FIG. 3 according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating an example of image data according to the embodiment of the present invention.

FIG. 7 is a diagram showing an example of an abnormal image generated when a code error (code error) has occurred in the embodiment of the present invention.

FIG. 8 is a configuration diagram illustrating an internal configuration of an image storage unit according to the embodiment of the present invention.

FIG. 9 is a flowchart for explaining an operation in which the image storage unit encodes image data and creates reduced image data in the embodiment of the present invention.

FIG. 10 is a flowchart illustrating an operation of the image storage unit according to the embodiment of the present invention for determining whether there is a code error (code error) in the code data.

FIG. 11 is an example of a message notified to a user when a code error (code error) occurs in code data according to the embodiment of the present invention.

FIG. 12 is a diagram showing a configuration of a memory area according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 101 scanner 102 A / D conversion unit 103 image processing unit 104 image storage unit 105 image output unit 106 operation unit 107 main control unit 201 memory 202 encoding unit 203 decoding unit 204 memory control unit 205 hard disk I / F unit 206 hard disk 207 code Encoding / decoding IC 801 Memory 802 Data comparing unit 803 Encoding unit 804 Decoding unit 805 Memory control unit 806 Hard disk I / F unit 807 Hard disk 808 Encoding / decoding IC

Claims (4)

[Claims] A first storage unit configured to store digital image data; a second storage unit configured to store encoded data obtained by encoding the image data; and n pixels in a horizontal direction of the image data. Reduced image generation means for generating reduced image data thinned out every m pixels in the vertical direction of image data, reduced image data created by the reduced image generation means, and code data stored by the second storage means Decoded image comparison means for comparing image data obtained by decoding the image data, and code error determination means for determining whether the reduced image data and the image data are different as a result of the comparison by the decoded image comparison means. The decoded image comparison means is configured to decode, for each of n pixels in the horizontal direction and m pixels in the vertical direction, image data obtained by decoding the code data stored by the second storage means. Comparing the reduced image data, wherein the code error determining means includes a code error in the code data when any of the pixels compared by the decoded image comparing means has a different value. An image data encoding / decoding device characterized in that the image data encoding / decoding device determines that there is an image. 2. The image data encoding / decoding apparatus according to claim 1, wherein said reduced image data is stored by said second storage means. 3. The image data encoding / decoding apparatus according to claim 2, wherein said reduced image data is stored by said first storage means. 4. The image processing apparatus according to claim 1, further comprising: display means for displaying that there is a coding error when said coding error determining means determines that there is a coding error in said coded data. Any one of claims 1 to 3
Item 3. The image data encoding / decoding device according to Item 1.