JP2003037737A - Image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processor that can reduce adverse effects on a mosquito distortion reduction filter given on a block border. SOLUTION: The image processor uses an in-block filter application discriminating means 6 and an in-block flat portion detection means 7, to respectively obtain an in-block filter application flag and an in-block flat portion pattern and allows an in-block pixel filter means 10, so as to recognize a block conducted by in-block filter processing and block border flat pixels, whose values are possibly fluctuated by the filter processing. The image processor uses an inter-pixel difference coding calculation means 4 to obtain a code of a difference between the block border flat portion pixels and pixels adjacent to the block border flat portion pixels, so as to inspect in advance, whether or not the block border pixels by the in-block filter processing can take pixel values for increasing the inter-pixel difference at the block border more than that of the original image, thereby deciding the processing applied to the border pixels.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, and more particularly to an image processing apparatus that reduces distortion caused when reproducing compression-coded image data by quantizing in block units.

[0002]

2. Description of the Related Art It is known that, in image data coded / decoded in block units, a distortion unique to a flat portion around an edge in a block occurs during decoding due to a quantization error in coding. . This distortion is called mosquito distortion, and occurs in the constituent pixels of each block, which is the unit of quantization during encoding. As a method of reducing mosquito distortion, a method of inspecting whether or not there is a flat portion around an edge where mosquito distortion is likely to occur in each coding block and filtering the flat pixels in the block based on the inspection result Is common.

[0003]

In the above method, the filtering process is performed in units of coding blocks. Therefore, as shown in FIG. 12, when there is no undulation of pixel values, the difference in pixel value at the boundary between the filter target block (N-1) and the adjacent block (N) becomes larger than that of the original image, and the block It distorts the boundaries. In order to reduce this distortion, the block image data after the mosquito distortion reduction filter must be inspected again to detect the distortion in the pixels around the block boundary, resulting in an increase in processing time and an increase in circuit scale.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an image processing apparatus capable of reducing an adverse effect on a block boundary of a mosquito distortion reduction filter. is there.

[0005]

According to one aspect of the present invention, an image processing apparatus includes an input image memory, an inter-pixel difference code calculating means, an intra-block filter application determining means, and an intra-block flat portion detecting means. An in-block pixel filter means, an in-block filter information holding means, a processed block image data holding means, a boundary pixel determination means, a boundary pixel processing means, and an image output means.

The input image memory holds the original image. The inter-pixel difference code calculation means calculates the code of the inter-pixel difference of the original image data obtained from the input image memory. The in-block filter application determining means determines whether or not the in-block filter processing can be applied to the processing target block by detecting an edge location and a flat location in the image data in the processing target block obtained from the input image memory. The in-block flat portion detecting means detects a flat portion of the image data in the processing target block obtained from the input image memory.
The in-block pixel filter means, when the in-block filter application determining means determines that the in-block filter is applied to the processing target block, based on the in-block flat portion information detected by the in-block flat portion detecting means, Filter processing is performed on flat portions of the image data in the processing target block. The in-block filter information holding means detects the inter-pixel difference code obtained by the inter-pixel difference code calculating means, the in-block filter processing applicability determination result obtained by the in-block filter application determining means, and the in-block flat portion detection. The in-block flat portion information obtained by the means is held. The processed block image data holding unit holds the processed block image data obtained by the in-block pixel filter unit. The boundary pixel determining means determines the inter-pixel difference code of the processing target block obtained by the inter-pixel difference code calculating means, the in-block filter processing applicability determination result of the processing target block obtained by the in-block filter application determining means, and the in-block flatness. Of the intra-block flat portion information of the processing target block obtained by the location detection means and the intra-block filter information held by the intra-block filter information holding means, the inter-pixel differential code regarding the adjacent block and the intra-block filtering processing regarding the adjacent block are applied. The state of the block boundary pixels of the block to be processed and the adjacent block is inspected based on the result of the feasibility judgment and the in-block flat portion information about the adjacent block, and the process for the block boundary pixel is determined. The boundary pixel processing means processes the block boundary pixels based on the boundary pixel determination result obtained by the boundary pixel determination means. The image output means outputs the image data from the in-block pixel filter means, the boundary pixel processing means, and the input image memory as a video signal.

[0007] Preferably, the inter-pixel difference code calculation means is an inter-pixel difference code near the block boundary of the processing target block, an inter-pixel difference code near the block boundary of the adjacent block, and a block between the processing target block and the adjacent block. The boundary pixel difference code between the boundary pixels is calculated.

Preferably, the boundary pixel determining means determines whether the intra-block filter processing is applicable when the intra-block filter processing application availability determination result of both or one of the target block and the adjacent block is valid. Refer to the in-block flat point information of the block for which is valid, and if the block flat point includes the block boundary pixel, the inter-pixel difference code near the block boundary of the block and the block of the block adjacent to the block It is preliminarily inspected from the difference code between the boundary pixels and the boundary pixel whether or not the block boundary pixel after the intra-block filter processing can take a pixel value that makes the difference between the pixels in the block boundary larger than the original image, and the inspection concerned. Based on the result, it is decided to perform the boundary processing on the block boundary pixel.

In the image processing apparatus, the in-block pixel filter means obtains the in-block filter processing applicability determination result of the block to be processed and the adjacent block by the in-block filter application determination means and the in-block filter information holding means. By recognizing the block to be subjected to the in-block filter processing, and obtaining the in-block flat portion information of the processing target block and the adjacent block by the in-block flat portion detection means and the in-block filter information holding means, By recognizing a block boundary flat pixel that may fluctuate and obtaining the sign of the pixel difference between the block boundary flat pixel and its adjacent pixel from the inter-pixel difference code calculation means, the block boundary is processed by the intra-block filter processing. Pixels compared to the original image An effect that makes it possible to check whether possible pixel values so as to increase the inter-pixel difference of the block boundary in advance.

Preferably, the boundary pixel determining means determines whether the intra-block filter processing is applicable if the intra-block filter processing application availability determination result of both or one of the target block and the adjacent block is valid. Refer to the in-block flat point information of the block for which is valid, and if the block flat point includes the block boundary pixel, the inter-pixel difference code near the block boundary of the block and the block of the block adjacent to the block From the difference code between the boundary pixels and the boundary pixel, the number of pixels that can take a pixel value that makes the block boundary pixel after the intra-block filter processing larger the pixel difference of the block boundary than the original image is counted, and the number of pixels is When the number exceeds the predetermined number, it is decided to perform the boundary processing on the block boundary pixels.

In the above image processing apparatus, the in-block pixel filter means obtains the in-block filter processing applicability determination result of the block to be processed and the adjacent block by the in-block filter application determination means and the in-block filter information holding means. By recognizing the block to be subjected to the filter processing, and obtaining the in-block flat portion information of the processing target block and the adjacent block by the in-block flat portion detecting means and the in-block filter information holding means, the pixel value changes in the in-block filter processing. By recognizing a possible block boundary flat pixel and obtaining the sign of the difference between the pixel of the block boundary flat pixel and the pixel adjacent thereto from the inter-pixel difference code calculation means, the block boundary pixel is determined by the intra-block filter processing. Block compared to the original image When it is possible to count the number of pixels that can take a pixel value that increases the difference between the pixels of the field and check in advance whether the number of pixels exceeds a predetermined number, and when the number of pixels exceeds the predetermined number In addition, it is possible to determine the execution of the boundary processing for the block boundary pixels that can take pixel values such that the boundary pixels of the block have a larger pixel difference at the block boundary than the original image by the intra-block filter processing. Have.

Preferably, the boundary pixel determining means determines whether the intra-block filter processing is applicable when the intra-block filter processing application availability determination result of both or one of the target block and the adjacent block is valid. Refer to the in-block flat portion information of the block in which is valid, if the block flat pixel includes the block boundary pixel, and if the peripheral pixels of the block boundary pixel are continuously flat by a predetermined number or more, the From the difference code between pixels near the block boundary of the block and the difference code between boundary pixels with the block boundary pixel of the block adjacent to the block, the block boundary pixel after the intra-block filter processing is compared with the original image. It is inspected in advance whether a pixel value that can increase the Lock boundary pixels to determine the implementation of the boundary processing.

In the above image processing apparatus, the in-block pixel filter means obtains the in-block filter processing applicability determination results of the block to be processed and the adjacent block by the in-block filter application determination means and the in-block filter information holding means. By recognizing the block to be filtered, and obtaining the in-block flat portion information of the target block and the adjacent block by the in-block flat portion detecting means and the in-block filter information holding means, the pixel value changes in the in-block filter processing. Recognize possible block boundary flat pixels, recognize whether the peripheral pixels of the block boundary flat pixels in the same block are flat, and if the peripheral pixels of the block boundary pixels are flat, the block boundary flat pixels And the pixel about the pixel adjacent to it By obtaining the code of the difference between the pixels from the inter-pixel difference code calculating means, the pixel value of the boundary pixel included in the flat part of the block can be taken to be larger than the original image by the intra-block filtering process. It has an effect of enabling to inspect whether or not in advance.

Preferably, the boundary pixel determining means determines whether the in-block filter processing is applicable if the in-block filter processing application availability determination result of both or one of the target block and the adjacent block is valid. Refer to the in-block flat portion information of the block in which is valid, if the block flat pixel includes the block boundary pixel, and the peripheral pixels of the block boundary pixel are continuously flat by a predetermined number or more, the From the difference code between pixels near the block boundary of the block and the difference code between boundary pixels with the block boundary pixel of the block adjacent to the block, the block boundary pixel after the intra-block filter processing is compared with the original image. The number of pixels that can take a pixel value that increases The block boundary pixels to determine the implementation of the boundary processing in the case.

In the image processing apparatus, the in-block pixel filter means obtains the in-block filter processing applicability determination result of the block to be processed and the adjacent block by the in-block filter application determination means and the in-block filter information holding means. By recognizing the block to be subjected to the filter processing, and obtaining the in-block flat portion information of the processing target block and the adjacent block by the in-block flat portion detecting means and the in-block filter information holding means, the pixel value changes in the in-block filter processing. Recognizing possible block boundary flat pixels, recognizing whether the peripheral pixels of the block boundary pixels in the same block are flat, and if the peripheral pixels of the block boundary flat pixels are flat, the block boundary flat pixels And the pixel about the pixel adjacent to it By obtaining the code of the difference between the pixels from the inter-pixel difference code calculation means, the pixel value of the boundary pixel included in the flat part of the block by the intra-block filter processing can be larger than that of the original image. It is possible to count the number of pixels and check in advance whether or not the number of pixels exceeds a predetermined number.When the number of pixels exceeds a predetermined number, the boundary pixel of the block is compared with the original image by the intra-block filter processing. This has the effect of making it possible to determine the implementation of boundary processing for block boundary pixels that can take pixel values that increase the pixel difference between block boundaries.

Preferably, the boundary pixel processing means outputs the boundary pixel of the original image instead of the intra-block filter processing pixel for the boundary processing execution pixel.

In the above-mentioned pixel processing device, the intra-block filter is applied to the block boundary pixel having a pixel value that makes the inter-pixel difference of the block boundary larger than the original image by the intra-block filter processing based on the inspection result. By selecting the boundary pixel of the original image instead of the processed pixel, it is possible to prevent the inter-pixel difference value at the block boundary from becoming larger than that of the original image.

According to another aspect of the present invention, an image processing apparatus has an input image memory, an inter-pixel difference code calculating means, an inter-pixel difference value calculating means, an intra-block filter application determining means, and an intra-block flatness. The position detecting unit, the in-block pixel filtering unit, the in-block filter information holding unit, the processed block image data holding unit, the boundary pixel determining unit, the boundary pixel processing unit, and the image output unit are provided.

The input image memory holds the original image. The inter-pixel difference code calculation means calculates the code of the inter-pixel difference of the original image data obtained from the input image memory. The inter-pixel difference value calculation means calculates the inter-pixel difference value between the block boundary pixel pixel of the processing target block of the original image data obtained from the input image memory and the block boundary pixel of the adjacent block. The in-block filter application determining means determines whether or not the in-block filter processing can be applied to the processing target block by detecting an edge location and a flat location in the image data in the processing target block obtained from the input image memory. The in-block flat portion detecting means detects a flat portion in the processing target block obtained from the input image memory.
The in-block pixel filter means, when the in-block filter application determining means determines that the in-block filter is applied to the block to be processed, based on the in-block flat portion information detected by the in-block flat portion detecting means, Filter processing is performed on the flat part of the processing target block. The in-block filter information holding means is
The inter-pixel difference code obtained by the inter-pixel difference code calculation means, the in-block filter processing applicability determination result obtained by the in-block filter application determination means, and the block obtained by the in-block flat portion detection means The flat area information and are held. The processed block image data holding unit holds the processed block image data obtained by the in-block pixel filter unit. The boundary pixel determining means determines the inter-pixel difference code of the processing target block obtained by the inter-pixel difference code calculating means, the in-block filter processing applicability determination result of the processing target block obtained by the in-block filter application determining means, and the in-block flatness. The intra-block flat portion information of the block to be processed obtained by the location detection means and the block filter information held by the intra-block filter information holding means are applied to the inter-pixel differential code regarding the adjacent block and the intra-block filter processing regarding the adjacent block. The state of the block boundary pixels of the block to be processed and the adjacent block is inspected based on the result of the propriety determination and the in-block flat portion information about the adjacent block, and the process for the block boundary pixel is determined. The boundary pixel processing means processes the block boundary pixels based on the boundary pixel determination result obtained by the boundary pixel determination means. Image output means
The image data from the in-block pixel filter means, the boundary pixel processing means, and the input image memory is output as a video signal.

Preferably, the inter-pixel difference code calculation means is an inter-pixel difference code near the block boundary of the processing target block, an inter-pixel difference code near the block boundary of the adjacent block, and a block between the processing target block and the adjacent block. The boundary pixel difference code between the boundary pixels is calculated.

Preferably, the boundary pixel determining means determines whether the intra-block filter processing is applicable when the intra-block filter processing application availability determination result of both or one of the target block and the adjacent block is valid. Refer to the in-block flat portion information of the block in which is valid, the block flat pixel includes the block boundary pixel, and the block boundary pixel is continuously flat for a predetermined number or more, and the processing target block If the pixel difference value between the block boundary pixel of the block and the block boundary pixel of the adjacent block is greater than or equal to the first threshold value and less than or equal to the second threshold value, the inter-pixel difference code near the block boundary of the block and the block After performing the intra-block filter processing from the boundary pixel difference code between the block boundary pixel of the block adjacent to Lock boundary pixel if possible pixel values so as to increase the inter-pixel difference of the block boundary compared to the original image in advance inspection, to determine the implementation of the boundary processing for the block boundary pixels based on the inspection results.

In the above image processing apparatus, the in-block pixel filter means obtains the in-block filter processing applicability determination result of the block to be processed and the adjacent block by the in-block filter application determination means and the in-block filter information holding means. By recognizing the block to be subjected to the filter processing, and obtaining the in-block flat portion information of the processing target block and the adjacent block by the in-block flat portion detecting means and the in-block filter information holding means, the pixel value changes in the in-block filter processing. Recognize possible block boundary flat pixels, recognize whether the peripheral pixels of the block boundary flat pixels in the same block are flat, and if the peripheral pixels of the block boundary flat pixel are flat, block boundary flat About a pixel and its neighbors A pixel value that causes a boundary pixel included in a flat portion of a block to have a larger pixel difference at the block boundary than the original image by obtaining the code of the pixel difference from the pixel difference code calculation means by the intra-block filter processing It is possible to check in advance whether or not it is possible, and if the boundary pixel can take a pixel value that makes the difference between the pixels of the block boundary larger than the original image, the pixel of the block boundary pixel of the processing target block and the adjacent block By obtaining the inter-pixel difference value from the inter-pixel difference value calculating means, the inter-pixel difference value between the boundary pixel and the boundary pixel of the block adjacent to the block including the boundary pixel is larger than the first threshold value and the second threshold value. If the difference between pixels is larger than the first threshold value and smaller than the second threshold value, the intra-block filter can be checked. Boundary pixels of a block by physical has an effect that makes it possible to determine the implementation of the boundary processing for the block boundary pixels of possible pixel values so as to increase the inter-pixel difference of the block boundary compared to the original image.

Preferably, the boundary pixel determining means determines whether the intra-block filter processing is applicable when the intra-block filter processing application availability determination result of both or one of the target block and the adjacent block is valid. Refer to the in-block flat portion information of the block for which the block is valid, the block flat pixel includes the block boundary pixel, and the peripheral pixels of the block boundary pixel are continuously flat by a predetermined number or more, and the processing is performed. When the pixel difference value between the block boundary pixel of the target block and the block boundary pixel of the adjacent block is greater than or equal to the first threshold value and less than or equal to the second threshold value, an inter-pixel difference code near the block boundary of the block and The intra-block filter processing is performed based on the difference code between the boundary pixels with the block boundary pixel of the block adjacent to the block. Counts the number of pixels that can take pixel values so that the subsequent block boundary pixels can increase the difference between pixels at the block boundary compared to the original image, and if the number of pixels exceeds a predetermined number, perform boundary processing on the block boundary pixels. To decide.

In the above image processing apparatus, the in-block pixel filter means obtains the in-block filter processing applicability determination result of the block to be processed and the adjacent block by the in-block filter application determination means and the in-block filter information holding means. By recognizing the block to be subjected to the filter processing, and obtaining the in-block flat portion information of the processing target block and the adjacent block by the in-block flat portion detecting means and the in-block filter information holding means, the pixel value changes in the in-block filter processing. Recognize possible block boundary flat pixels, recognize whether the peripheral pixels of the block boundary flat pixels in the same block are flat, and if the peripheral pixels of the block boundary flat pixel are flat, block boundary flat About a pixel and its neighbors A pixel value that causes a boundary pixel included in a flat portion of a block to have a larger pixel difference at the block boundary than the original image by obtaining the code of the pixel difference from the pixel difference code calculation means by the intra-block filter processing It is possible to check in advance whether or not it is possible, and if the boundary pixel can take a pixel value that makes the difference between the pixels of the block boundary larger than the original image, the pixel of the block boundary pixel of the processing target block and the adjacent block By obtaining the inter-pixel difference value from the inter-pixel difference value calculating means, the inter-pixel difference value between the boundary pixel and the boundary pixel of the block adjacent to the block including the boundary pixel is larger than the first threshold value and the second threshold value. It is possible to count the number of block boundary pixels that are smaller than the value and check in advance whether or not the number of pixels exceeds a predetermined number. An effect that makes it possible to determine the implementation of the boundary processing for the block boundary pixels if more than a few.

Preferably, the boundary pixel processing means outputs the boundary pixel of the original image instead of the intra-block filter processed pixel for the boundary processing execution pixel.

In the image processing apparatus, the block boundary pixel among the block boundary pixels having a pixel value that makes the inter-pixel difference of the block boundary larger than the original image by the intra-block filter processing based on the inspection result. The peripheral pixels in the block to which the pixel belongs are flat, and the inter-pixel difference value between the block boundary pixel and the boundary pixel of the block adjacent to the block to which the block boundary pixel belongs is the first pixel.
For the block boundary pixels that are larger than the threshold value and smaller than the second threshold value, the pixel boundary difference value of the block boundary is compared with the original image by selecting the boundary pixel of the original image instead of the intra-block filtering pixel. It has the effect of allowing it not to grow.

Preferably, the boundary pixel processing means smoothes the boundary processing execution pixel by the boundary processing execution pixel after the intra-block filter processing and its adjacent pixel.

In the above-mentioned image processing apparatus, the block boundary pixel among the block boundary pixels having a pixel value which makes the difference between pixels of the block boundary larger than the original image by the intra-block filter processing based on the inspection result. The peripheral pixels in the block to which the pixel belongs are flat, and the inter-pixel difference value between the block boundary pixel and the boundary pixel of the block adjacent to the block to which the block boundary pixel belongs is the first pixel.
Block boundary pixels that are larger than the threshold value and smaller than the second threshold value, the block boundary pixel after the intra-block filter processing, the pixel adjacent to the block boundary pixel of the block to which the block boundary pixel belongs, and the block boundary pixel belong to This has the effect of enabling smoothing with the boundary pixels of blocks adjacent to the block.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and the description thereof will not be repeated.

(First Embodiment) FIG. 1 is a block diagram showing the arrangement of an image processing apparatus according to the first embodiment of the present invention. The image processing apparatus shown in FIG. 1 includes an input image memory 1, a block number counter 2, and an address generating means 3.
An inter-pixel difference code calculation means 4, an intra-block filter application determination means 6, an intra-block flat portion detection means 7,
In-block filter application flag holding means 8, flat portion pattern holding means 9, and in-block pixel filter means 1
0, boundary pixel holding means 11, boundary pixel determination means 12
And a boundary pixel processing means 13 and an image output means 14.

The input image memory 1 holds the input image data. The block number counter 2 counts the block number to be processed. The address generating means 3 generates a memory address of a pixel in the block corresponding to the block number to be processed. The inter-pixel difference code calculation means 4 is
The left block boundary code pattern of the processing target block data read from the input image memory 1, the right block boundary code pattern of the adjacent block data, and the block boundary code pattern of the processing target block image data and the adjacent block image data are output. . The in-block filter application determining unit 6 generates an in-block filter application flag of the processing target block image data read from the input image memory 1. The in-block flat portion detecting means 7 detects a flat portion of the processing target block image data read from the input image memory 1 and generates an in-block flat portion pattern. The in-block filter application flag holding means 8 holds the in-block filter application flag and outputs it as an in-block filter application history. The flat spot pattern holding means 9 holds the flat spot pattern within the block on the right block boundary among the flat spot patterns within the block, and outputs it as the right block boundary flat spot pattern. The in-block pixel filter means 10 performs a smoothing process on the processing target block image data read from the input image memory 1 based on the in-block filter application flag and the in-block flat spot pattern. The boundary pixel holding unit 11 holds the right block boundary pixel in the output of the in-block pixel filter unit 10. The boundary pixel determination means 12 is based on the left block boundary code pattern, the right block boundary code pattern, the block boundary code pattern, the in-block filter application flag, the in-block filter application history, the in-block flat spot pattern, and the right block boundary flat spot pattern. Processing is performed on the boundary pixel between the block to be processed and the adjacent block, and a right boundary processing determination signal and a left boundary processing determination signal are generated.
The boundary pixel processing means 13 performs processing on the boundary pixels between the block to be processed and the adjacent block based on the right boundary processing determination signal and the left boundary processing determination signal, and outputs the right block boundary output data and the left block boundary output data. Output. The image output means 14 outputs the right block boundary output data, the left block boundary output data, and the processed image non-block boundary image data from the boundary pixel processing means 13 as video signals.

FIG. 2 shows the boundary pixel processing means 1 shown in FIG.
3 is a block diagram showing the internal configuration of FIG. As shown in FIG. 2, the boundary pixel processing means 13 includes the right boundary pixel selecting means 20.
And a left boundary pixel selection unit 21. The right boundary pixel selection means 20 selectively outputs the original image right block boundary pixel data and the processed image right block boundary pixel data based on the right boundary processing determination signal. The left boundary pixel selection means 21
The original image left block boundary pixel data and the processed image left block boundary pixel data are selectively output based on the left boundary processing determination signal.

Next, the operation of the image processing apparatus configured as described above will be described. In the following description, the block corresponding to the block number N is the block (N), the image data in the block (N) is the block image data (n), and the in-block filter processing is performed on the block image data (n). The result of performing the above is referred to as block image data (n ′), and the state where the block to be processed is block (N) and the adjacent block is block (N−1) is referred to as block processing status N. Also, as shown in FIG.
The size of one block is vertical a pixels × horizontal b pixels, and the reading order of the block image data stored in the input image memory 1 is the block number order in FIG. Then, in the block processing status N (processing target block = block N, adjacent block = block N−1), the horizontal mosquito distortion reduction for the block image data (n) of the block N and the block N−1 and the block N are performed. The operation in the processing for the boundary pixel will be described.

The image data decoded by the decoding device is stored in the input image memory 1. In the address generation means 3,
The processing target block memory address of the block image data (n) of the block (N) output by the block number counter 2 is generated. The processing target block image data (n) read from the input image memory 1 includes an inter-pixel difference code calculation means 4, an intra-block filter application determination means 6, an intra-block flat portion detection means 7, and an intra-block pixel filter means 10. Is output to.

The inter-pixel difference code calculation means 4 generates an adjacent block boundary pixel memory address (n-1), and the original image right block boundary pixel data (n-) of the block (N-1).
1) is read out from the input image memory 1 as a pixel. next,
A block (N) and a block (N-) based on the original image right block boundary pixel data (n-1) read from the input image memory 1 and the processing target block image data (n) input from the input image memory 1. 1) a first inter-pixel difference code which is a code of a boundary pixel difference with respect to 1) and a second pixel which is a code of a pixel difference between a right block boundary pixel in the block (N-1) and its left adjacent pixel The difference code and the third inter-pixel difference code, which is the code of the pixel difference between the left block boundary pixel in the block (N) and its right adjacent pixel, are calculated. The first inter-pixel difference code uses a boundary a pixels as a block boundary code pattern, and the second inter-pixel difference code uses a boundary a pixels as a right block boundary code pattern (n-1).
The inter-pixel difference code of is output to the boundary pixel determination means 12 with the pixel a at the boundary as the left block boundary code pattern (n).

In the in-block filter application determining means 6, since mosquito distortion is likely to occur in a flat portion around the edge,
The absolute difference value between the pixels in the block (N) is calculated, and when the inter-pixel difference value is larger than the edge detection threshold value, it is determined to be an edge portion, and the inter-pixel difference value is the flatness detection threshold value. If it is smaller, it is determined to be a flat portion, and if both the edge portion and the flat portion exist in the block image data (n) to be processed, it is determined to apply the in-block pixel filter to the block (N), and the in-block filter is determined. Enable the apply flag (n).

The in-block flat portion detecting means 7 calculates the absolute difference value between the pixels in the block (N), and when the inter-pixel difference value is smaller than the flatness detection threshold value, it is determined to be a flat portion. An in-block flat portion pattern (n) is generated based on the determination result.

In the in-block pixel filter means 10, if the in-block filter application flag (n) of the block (N) generated by the in-block filter application determination means 6 is valid, the in-block flat portion detection means 7 According to the in-block flat portion pattern (n) of the block (N) generated in step 3, smoothing processing is performed by the flat pixel in the processing target block image data (n) and the three pixels of the two pixels adjacent in the horizontal direction. .

When the in-block filter application flag (n) of the block (N) generated by the in-block filter application determining means 6 is invalid, the block image data to be processed is processed regardless of the state of the in-block flat portion pattern. The smoothing process for (n) is not performed. Further, the right block boundary pixel of the block (N) is sent to the boundary pixel holding means 11 and the left block boundary pixel of the block (N) is the processed image left block boundary pixel data (n ′) regardless of whether or not the smoothing process is performed. Is output to the boundary pixel processing means 13 and the non-block boundary pixels of the block (N) are output to the image output means 14 as processed image non-block boundary pixel data (n ′).

The boundary pixel holding means 11 holds a right block boundary pixels of the block (N), which is the output from the in-block pixel filter means 10, for one block processing period. The retained data is the block processing status N + 1
(Processing target block = block N + 1, adjacent block =
At the time of block N), the processed image of the adjacent block is output to the boundary pixel processing unit 13 as the right block boundary pixel.

In-block filter application flag holding means 8
Then, the in-block filter application flag (n) is held for one block processing period. The retained in-block filter application flag (n) is a boundary pixel as an in-block filter application history (n-1) of an adjacent block when the block processing status N + 1 (processing target block = block N + 1, adjacent block = block N). It is output to the determination means 12.

The flat spot pattern holding means 9 holds the flat spot pattern in the block at the right block boundary among the flat spot patterns (n) in the block (N) for one block processing period. The held pattern is a block processing status N + 1 (processing target block = block N +
1, adjacent block = block N), the pattern is output to the boundary pixel determination unit 12 as a right block boundary flat portion pattern of the adjacent block.

In the boundary pixel determining means 12, the block processing status N-1 (processing target block = block N-
1, adjacent block = block N−2), the in-block filter application history (n−) of the block (N−1) generated by the in-block filter application determination unit 6 and held by the in-block filter application flag holding unit 8 1)
And either or both of the in-block filter application flags (n) of the block (N) from the in-block filter application determining means 6 are valid, the block processing status N-1 (processing target block = block N- 1, adjacent block = block N-2), the right block boundary flat pattern of the block (N-1) generated by the in-block flat portion detection unit 7 and held by the flat portion pattern holding unit 9 and the flat inside block In-block flat part pattern (n) of the block (N) from the part detecting means 7
And the block (N− from the inter-pixel difference code calculation means 4).
1) the right block boundary code pattern (n-1), the block boundary code pattern of the block boundary between the block (N-1) and the block (N), and the left block boundary code pattern (n) of the block (N) The block (N-
The boundary processing of the right block boundary pixel of 1) and the left block boundary pixel of the block (N) is determined.

In the following description, (1) block (N-
In-block filter application history (n-1) of 1) is valid, and in-block filter application flag (n) of block (N)
Is invalid, (2) If the in-block filter application history (n-1) of the block (N-1) is invalid and the in-block filter application flag (n) of the block (N) is valid, (3) ) The case where both the intra-block filter application history (n-1) of the block (N-1) and the intra-block filter application flag (n) of the block (N) are both valid will be described separately.

(1) When the in-block filter application history (n-1) of the block (N-1) is valid and the in-block filter application flag (n) of the block (N) is invalid, the block boundary flat pattern is set. Refer to the block (N-
Among the right block boundary pixels of 1), the right block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified, and the right block boundary code pattern (n-1) of the block (N-1) is identified. The code corresponding to the position of the right block boundary flat pixel is the same as the code corresponding to the position between the right block boundary flat pixel and the block boundary pixel of the block (N) adjacent thereto in the block boundary code pattern. Inspect whether or not. When the signs are the same, the right block boundary flat pixel of the block (N-1) corresponding to that position is the intra-block pixel filter means 10
Pixel values are taken so that the difference between the block boundaries becomes larger than that of the original image by the smoothing process of. Boundary pixel determination means 12
Then, a right boundary processing determination signal that makes it effective to execute the boundary processing for the right block boundary flat pixel of the block (N−1) is generated. Since the in-block filter application flag (n) is invalid for the left block boundary pixel of the block (N), a left boundary processing determination signal that invalidates the boundary processing is generated.

(2) In-block filter application history (n-1) of block (N-1) is invalid and in-block filter application flag (n) of block (N) is valid. Reference and block (N)
Of the left block boundary pixels, the left block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified, and the left block boundary flat pixel of the left block boundary code pattern (n) of the block (N) is identified. , The block corresponding to the position of the block boundary code pattern, the left block boundary flat pixel and the adjacent block (N-
It is checked whether or not the code corresponding to the position between the block boundary pixel of 1) is the same. When the signs are the same, the left block boundary flat pixel of the block (N) corresponding to the position has a pixel value such that the difference between the block boundaries becomes larger than that of the original image by the smoothing process of the in-block pixel filter means 10. take. The boundary pixel determination unit 12 generates a left boundary processing determination signal that makes it effective to perform the boundary processing on the left block boundary flat pixels of the block (N). Since the intra-block filter application history (n-1) is invalid for the right block boundary pixel of the block (N-1), the right boundary processing determination signal that invalidates the boundary processing is generated.

(3) When both the intra-block filter application history (n-1) of the block (N-1) and the intra-block filter application flag (n) of the block (N) are valid, refer to the right block boundary flat pattern. Block (N-
Among the right block boundary pixels of 1), the right block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified, and the block in the left block boundary pixel of the block (N) is referred to by referring to the in-block flat portion pattern. Among them, the left block boundary flat pixel on which the filtering process is performed by the in-block pixel filter unit 10 is specified, and the right block boundary flat pixel and the left block boundary flat pixel are adjacent to each other across the block boundary, The block boundary code pattern at the position corresponding to the position, the right block boundary code pattern (n-1) at the position corresponding to the right block boundary flat pixel, and the left block boundary code pattern at the position corresponding to the left block boundary flat pixel ( n) and check if these three codes are all the same. If the signs are the same, the block (N-
The right block boundary flat pixel of 1) and the left block boundary flat pixel of block (N) have pixel values such that the difference between the block boundaries becomes larger than that of the original image due to the smoothing processing by the in-block pixel filter means. Boundary pixel determination means 1
2, the right boundary processing determination signal and the left boundary processing for validating the boundary processing for the right block boundary flat pixel of the block (N-1) and the left block boundary flat pixel of the block (N-1) Generate a decision signal.

In the boundary pixel processing means 13, based on the right boundary processing determination signal in the right boundary pixel selection means 20, the original image right block boundary read from the input image memory 1 for the right block boundary pixel for which the boundary processing is effective. The boundary pixel holding unit 11 selects the pixel data (n-1) and regards the right block boundary pixel for which the execution of the boundary processing is invalid.
The processed image right boundary pixel data (n-1 ') is selected and output to the image output means 14 as right block boundary output data. Similarly, the left boundary pixel selection means 21 selects the original image left block boundary pixel data (n) read from the input image memory 1 for the left block boundary pixel for which the boundary processing is effective, based on the left boundary processing determination signal. Then, the processed image left boundary pixel data (n ′) from the boundary pixel holding unit 11 is selected for the left block boundary pixel for which the boundary processing is invalid, and is output to the image output unit 14 as the left block boundary output data.

As described above, according to the first embodiment, the sign of the difference between pixels of the original images of the two adjacent blocks forming the block boundary, the result of determination as to whether or not the intra-block filtering process can be applied, and the intra-block flat portion. By using the information, it is inspected in advance whether or not the pixel value of the boundary pixel of the block can increase the difference between pixels of the block boundary as compared with the original image by the intra-block filtering process, and the intra-block filter for such pixel is performed. By selecting the boundary pixel of the original image instead of the processing pixel, it is possible to prevent the inter-pixel difference value at the block boundary from becoming larger than that of the original image, and it is possible to improve the image quality.

(Second Embodiment) FIG. 4 is a block diagram showing the arrangement of an image processing apparatus according to the second embodiment of the present invention. The image processing apparatus shown in FIG. 4 includes a boundary pixel determining means 42 instead of the boundary pixel determining means 12 shown in FIG. Other configurations are the same as those of the image processing apparatus shown in FIG.

The boundary pixel determining means 42 determines the left block boundary code pattern, the right block boundary code pattern, the block boundary code pattern, the in-block filter application flag, the in-block filter application history, the in-block flat part pattern, and the right block boundary flat part. Based on the pattern and the block boundary pixel detection number threshold value, the process for the boundary pixel between the target block and the adjacent block is determined, and the right boundary process determination signal and the left boundary process determination signal are generated.

In the boundary pixel determining means 42, the block processing status N-1 (processing target block = block N-
1, adjacent block = block N−2), the in-block filter application history of the block (N−1) generated by the in-block filter application determination means 6 and held in the in-block filter application flag holding means 8, and the block If either or both of the block internal filter application flag of the block (N) from the internal filter application determining means 6 is valid, the block processing status N-1 (processing target block = block N-1, adjacent block =) A right block boundary flat pattern of the block (N-1) which is generated by the in-block flat portion detection unit 7 at the time of block N-2) and is held by the flat portion pattern holding unit 9;
In-block flat part pattern (n) of the block (N) from the in-block flat part detecting means 7 and right block boundary code pattern (n-1) of the block (N-1) from the inter-pixel difference code calculating part 4 And the block boundary code pattern of the block boundary between the block (N-1) and the block (N) and the left block boundary code pattern of the block (N), the right block boundary pixel of the block (N-1) And the boundary processing of the left block boundary pixel of the block (N) is determined.

In the following description, (1) block (N-
When the in-block filter application history of 1) is valid and the in-block filter application flag of block (N) is invalid, (2) the in-block filter application history of block (N-1) is invalid and the block (N) of block (N) is When the in-block filter application flag is valid, (3) block (N-1)
The in-block filter application history and the in-block filter application flag of block (N) will be separately described.

(1) When the in-block filter application history of the block (N-1) is valid and the in-block filter application flag of the block (N) is invalid, the right block boundary flat pattern is referred to, and the block (N-
Among the right block boundary pixels of 1), the right block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified, and the right block boundary code pattern (n-1) of the block (N-1) is identified. The code corresponding to the position of the right block boundary flat pixel is the same as the code corresponding to the position between the right block boundary flat pixel and the block boundary pixel of the block (N) adjacent thereto in the block boundary code pattern. Inspect for existence. When the signs are the same, the right block boundary flat pixel of the block (N-1) corresponding to that position is the intra-block pixel filter means 1
Pixel values are taken so that the difference between block boundaries becomes larger than that of the original image by the smoothing process of 0. Boundary pixel determination means 4
2 counts the number of right block boundary flat pixels of the block (N−1), and if the number is larger than the block boundary pixel detection number threshold value, the right block boundary flat pixel of the block (N−1). A right boundary processing determination signal is generated that validates the boundary processing for. Since the intra-block filter application flag is invalid for the left block boundary pixel of the block (N), a left boundary processing determination signal that invalidates the boundary processing is generated.

(2) When the in-block filter application history of the block (N-1) is invalid and the in-block filter application flag of the block (N) is valid, the in-block flat portion pattern is referred to, and the block (N)
Of the left block boundary pixels, the left block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified, and is located at the position of the left block boundary flat pixel in the left block boundary code pattern of the block (N). It is checked whether or not the corresponding code and the code corresponding to the position between the left block boundary flat pixel and the block boundary pixel of the block (N-1) adjacent thereto in the block boundary code pattern are the same. When the signs are the same, the left block boundary flat pixel of the block (N) corresponding to the position has a pixel value such that the difference between the block boundaries becomes larger than that of the original image by the smoothing process of the in-block pixel filter means 10. take. The boundary pixel determination means 42 counts the number of left block boundary flat pixels of such a block (N), and when the number is larger than the block boundary pixel detection number threshold value, the left block boundary pixel of the block (N) is determined. A left boundary processing determination signal that makes it effective to execute the boundary processing is generated. Since the intra-block filter application history is invalid for the right block boundary pixel (n-1) of the block (N-1), the right boundary processing determination signal that invalidates the boundary processing is generated.

(3) When both the in-block filter application history of block (N-1) and the in-block filter application flag of block (N) are valid, the block (N-) is referred to the right block boundary flat pattern.
Among the right block boundary pixels of 1), the right block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified, and the in-block flat portion pattern is referred to to identify the left block boundary pixel of the block (N). Among them, the left block boundary flat pixels to be filtered by the in-block pixel filter means 10 are specified, and the right block boundary flat pixel and the left block boundary flat pixel are adjacent to each other across the block boundary. The block boundary code pattern at the position corresponding to the position, the right block boundary code pattern at the position corresponding to the right block boundary flat pixel, and the left block boundary code pattern at the position corresponding to the left block boundary flat pixel are inspected, and Check if all three signs are the same. When the signs are the same, the right block boundary flat pixel of the block (N-1) and the left block boundary flat pixel of the block (N) corresponding to the position are converted into the original image by the smoothing process of the in-block pixel filter means. Pixel values are taken so that the difference between the block boundaries becomes larger than that of the other blocks. The boundary pixel determining unit 42 counts the number of right block boundary flat pixels of the block (N−1) and the left block boundary flat pixels of the block (N), and the number of each block boundary pixel detection number threshold value. Generate a right boundary processing determination signal and a left boundary processing determination signal that enable execution of boundary processing for the right block boundary flat pixel of block (N-1) and the left block boundary flat pixel of block (N) when they are larger. To do.

In the boundary pixel processing means 13, based on the right boundary processing determination signal in the right boundary pixel selection means 20, the original image right block boundary read from the input image memory 1 for the right block boundary pixel for which the boundary processing is effective. The boundary pixel holding unit 11 selects the pixel data (n-1) and regards the right block boundary pixel for which the boundary processing is invalid.
The processed image right boundary pixel data (n-1 ') is selected and output to the image output means 14 as right block boundary output data. Similarly, the left boundary pixel selection means 21 selects the original image left block boundary pixel data (n) read from the input image memory 1 for the left block boundary pixel for which the boundary processing is effective, based on the left boundary processing determination signal. Then, the processed image left boundary pixel data (n ′) from the boundary pixel holding unit 11 is selected for the left block boundary pixel for which the boundary processing is invalid, and is output to the image output unit 14 as the left block boundary output data.

As described above, according to the second embodiment, the sign of the pixel difference between the original images of two adjacent blocks forming the block boundary, the in-block filter processing applicability determination result, and the in-block flat portion. Using information, it is preliminarily checked by the intra-block filtering process whether the pixel value of the boundary pixel of the block can be larger than that of the original image, and the number of such block boundary pixels. Is greater than a certain threshold value given as the threshold value for the number of detected block boundary pixels, by selecting the boundary pixel of the original image instead of the intra-block filter processed pixel for the block boundary pixel, It is possible to prevent the value from becoming larger than the original image, and adjust the degree of processing for block boundaries. Theft becomes possible, it is possible to achieve a high image quality.

(Third Embodiment) FIG. 5 is a block diagram showing the arrangement of an image processing apparatus according to the third embodiment of the present invention. The image processing apparatus shown in FIG. 5 has the flat portion pattern holding means 9 and the boundary pixel determination means 12 shown in FIG.
Instead, the flat part pattern holding means 59 and the boundary pixel determining means 62 are provided. Other configurations are the same as those of the image processing apparatus shown in FIG.

The flat part pattern holding means 59 holds the flat part pattern in the block around the right block boundary among the flat part patterns in the block and outputs it as the flat part pattern around the right block boundary.

The boundary pixel determining means 62 determines the left block boundary code pattern, the right block boundary code pattern, the block boundary code pattern, the in-block filter application flag, the in-block filter application history, the in-block flat location pattern, and the right block boundary peripheral flatness. The processing for the boundary pixel between the block to be processed and the adjacent block is determined based on the location pattern, and the right boundary processing determination signal and the left boundary processing determination signal are generated.

The flat portion pattern holding means 59 holds the flat portion in-block patterns around the right block boundary of the in-block flat portion pattern (n) of the block (N) for one block processing period. The held pattern is, when the block processing status N + 1 (processing target block = block N + 1, adjacent block = block N),
The pattern is output to the boundary pixel determination means 62 as a flat pattern around the right block boundary of the adjacent block.

In the boundary pixel determining means 62, the block processing status N-1 (processing target block = block N-
1, adjacent block = block N−2), the in-block filter application history (n−) of the block (N−1) generated by the in-block filter application determination unit 6 and held by the in-block filter application flag holding unit 8 1)
And either or both of the in-block filter application flags (n) of the block (N) from the in-block filter application determining means 6 are valid, the block processing status N-1 (processing target block = block N- 1. Adjacent block = block N−2), the flat portion pattern holding means 59 generated by the flat portion inside block detecting means 7
A right block boundary peripheral flat portion pattern (n-1) of the block (N-1) held in the block and a block flat portion pattern (n) of the block (N) from the intra-block flat portion detecting means 7; , The right block boundary code pattern (n-1) of the block (N-1) from the inter-pixel difference code calculating means 4, and the block boundary code pattern of the block boundary between the block (N-1) and the block (N). , And the left block boundary code pattern (n) of the block (N), the boundary processing of the right block boundary pixel of the block (N−1) and the left block boundary pixel of the block (N) is determined.

In the following description, (1) block (N-
In-block filter application history (n-1) of 1) is valid, and in-block filter application flag (n) of block (N)
Is invalid, (2) If the in-block filter application history (n-1) of the block (N-1) is invalid and the in-block filter application flag (n) of the block (N) is valid, (3) ) The case where both the in-block filter application history (n-1) of the block (N-1) and the in-block filter application flag (n) of the block (N) are valid will be described separately.

(1) When the in-block filter application history (n-1) of the block (N-1) is valid and the in-block filter application flag (n) of the block (N) is invalid, around the right block boundary By referring to the flat part pattern, the right block boundary flat pixel to be filtered by the intra-block pixel filter means 10 is specified among the right block boundary pixels of the block (N−1), and the right block boundary flat pixel is moved to the left. In the right block boundary code pattern (n
-1) A code corresponding to the position of the right block boundary flat pixel, and a position between the right block boundary flat pixel and the block boundary pixel of the block (N) adjacent thereto in the block boundary code pattern. Check if the signs are the same. If the signs are the same, the right block boundary flat pixel of the block (N-1) corresponding to that position is a pixel whose difference in block boundary becomes larger than that of the original image by the smoothing process of the in-block pixel filter means 10. Take a value. The boundary pixel determination unit 62 generates a right boundary processing determination signal that makes it effective to perform the boundary processing on the right block boundary flat pixel of the block (N−1). Since the in-block filter application flag (n) is invalid for the left block boundary pixel of the block (N), a left boundary processing determination signal that invalidates the boundary processing is generated.

(2) When the in-block filter application history (n-1) of the block (N-1) is invalid and the in-block filter application flag (n) of the block (N) is valid Reference and block (N)
Of the left block boundary pixels, the left block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified, and if the left block boundary flat pixel is continuously flat to the right by a predetermined number or more, The code corresponding to the position of the left block boundary flat pixel in the left block boundary code pattern (n) of the block (N) and the left block boundary flat pixel of the block boundary code pattern and the adjacent block (N-1) of the block boundary code pattern It is checked whether the code corresponding to the position with the block boundary pixel is the same. If the signs are the same, the block (N) corresponding to that position
The left flat pixel of the block boundary has a pixel value such that the difference in the block boundary becomes larger than that of the original image by the smoothing process of the in-block pixel filter means 10. The boundary pixel determining means 62 generates a left boundary processing determination signal that makes it effective to perform the boundary processing on the left block boundary flat pixels of the block (N). Since the intra-block filter application history (n-1) is invalid for the right block boundary pixel of the block (N-1), the right boundary processing determination signal that invalidates the boundary processing is generated.

(3) When the in-block filter application history (n-1) of block (N-1) and the in-block filter application flag (n) of block (N) are both valid Flat pattern around the right block boundary Of the right block boundary pixels of the block (N-1), the right block boundary flat pixel to be filtered by the intra-block pixel filter means 10 is specified, and the intra-block flat portion pattern is referred to for the block (N When a left block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified among the left block boundary pixels in (4), and a predetermined number or more of them are continuously flat to the left from the right block boundary flat pixel. Or, if the left block boundary flat pixel is continuously flat to the right by a predetermined number or more, the right block boundary flat pixel and the left block boundary are flat. Regarding a location where a flat pixel and a flat pixel are adjacent to each other across a block boundary, a block boundary code pattern at a position corresponding to the position and a right block boundary code pattern (n-1) at a position corresponding to the right block boundary flat pixel And the left block boundary code pattern (n) at a position corresponding to the left block boundary flat pixel,
Check if all three codes are the same.
When the signs are the same, the right block boundary flat pixel of the block (N−1) and the left block boundary flat pixel of the block (N) corresponding to the position are the original image by the smoothing process of the in-block pixel filter means 10. Pixel values are taken so that the difference between the block boundaries is larger than that of. In the boundary pixel determination means 62, a right boundary processing determination signal that validates the boundary processing for the right block boundary flat pixel of the block (N-1) and the left block boundary flat pixel of the block (N-1). And a left boundary processing determination signal is generated.

In the boundary pixel processing means 13, based on the right boundary processing determination signal in the right boundary pixel selection means 20, the original image right block boundary read from the input image memory 1 for the right block boundary pixel for which the boundary processing is effective. The boundary pixel holding unit 11 selects the pixel data (n-1) and regards the right block boundary pixel for which the boundary processing is invalid.
The processed image right boundary pixel data (n-1 ') is selected and output to the image output means 14 as right block boundary output data. Similarly, the left boundary pixel selection means 21 selects the original image left block boundary pixel data (n) read from the input image memory 1 for the left block boundary pixel for which the boundary processing is effective, based on the left boundary processing determination signal. Then, the processed image left boundary pixel data (n ′) from the boundary pixel holding unit 11 is selected for the left block boundary pixel for which the boundary processing is invalid, and is output to the image output unit 14 as the left block boundary output data.

As described above, according to the third embodiment, the sign of the pixel difference between the original images of the two adjacent blocks forming the block boundary, the in-block filter processing applicability determination result, and the in-block flat portion. By using the information, it is inspected in advance whether or not the block boundary pixel can take a pixel value that makes the difference between pixels of the block boundary larger than that of the original image by the intra-block filtering process. When the pixel is flat, by selecting the boundary pixel of the original image instead of the intra-block filter pixel for the block boundary pixel, the pixel difference value of the flat block boundary that is easily visually noticeable when distortion occurs Since it is possible to prevent the image from becoming larger than the image, high image quality can be achieved.

(Fourth Embodiment) FIG. 6 is a block diagram showing the arrangement of an image processing apparatus according to the fourth embodiment of the present invention. The image processing apparatus shown in FIG. 6 has the flat portion pattern holding means 9 and the boundary pixel determination means 12 shown in FIG.
Instead of this, the flat portion pattern holding means 79 and the boundary pixel determination means 82 are provided. Other configurations are the same as those of the image processing apparatus shown in FIG.

The flat spot pattern holding means 79 holds the flat spot pattern in the block around the right block boundary among the flat spot patterns in the block and outputs it as the flat spot pattern around the right block boundary.

The boundary pixel determining means 82 is a left block boundary code pattern, a right block boundary code pattern, a block boundary code pattern, an in-block filter application flag, an in-block filter application history, an in-block flat location pattern, and a right block boundary peripheral flat. Based on the location pattern and the block boundary pixel detection number threshold value, the processing for the boundary pixel between the block to be processed and the adjacent block is determined, and the right boundary processing determination signal and the left boundary processing determination signal are generated.

The flat portion pattern holding means 79 holds the flat portion in-block patterns on the right block boundary and the peripheral portion of the in-block flat portion pattern (n) of the block (N) for one block processing period. The held pattern is, when the block processing status N + 1 (processing target block = block N + 1, adjacent block = block N),
The pattern is output to the boundary pixel determination means 82 as a flat pattern around the right block boundary of the adjacent block.

In the boundary pixel judging means 82, the block processing status N-1 (processing target block = block N-
1, adjacent block = block N−2), the in-block filter application history of the block (N−1) generated by the in-block filter application determination means 6 and held in the in-block filter application flag holding means 8, and the block When either or both of the block internal filter application flags of the block (N) from the internal filter application determining means 6 are valid, the block processing status N-1 (processing target block = block N-1, adjacent block = block) At the time of (N-2), the flat pattern around the right block boundary of the block (N-1) generated by the in-block flat portion detecting means 7 and held by the flat portion pattern holding means 79 and the in-block flat portion detecting means 7 From the intra-block flat portion pattern (n) of the block (N) of FIG. Right block boundary code patterns of the block (N-1) and (n-1), blocks (N-
1) Referring to the block boundary code pattern of the block boundary between the block (N) and the left block boundary code pattern of the block (N), the right block boundary pixel of the block (N−1) and the block boundary code of the block (N) are referred to. The boundary processing of the left block boundary pixel is determined.

In the following description, (1) block (N-
When the in-block filter application history of 1) is valid and the in-block filter application flag of block (N) is invalid, (2) the in-block filter application history of block (N-1) is invalid and the block (N) of block (N) is When the in-block filter application flag is valid, (3) block (N-1)
The in-block filter application history and the in-block filter application flag of block (N) will be separately described.

(1) When the in-block filter application history of the block (N-1) is valid and the in-block filter application flag of the block (N) is invalid, the right block boundary peripheral flat pattern is referred to, and the block (N Among the right block boundary pixels of -1), the right block boundary flat pixel to be filtered by the in-block pixel filter unit 10 is specified, and the right block boundary code pattern (n-1) of the block (N-1) is specified. The code corresponding to the position of the right block boundary flat pixel is the same as the code corresponding to the position between the right block boundary flat pixel and the block boundary pixel of the adjacent block (N) in the block boundary code pattern. Inspect. If the signs are the same, the block (N-
The right block boundary flat pixel of 1) has a pixel value such that the difference between the block boundaries becomes larger than that of the original image by the smoothing processing by the in-block pixel filter means 10. The boundary pixel determination unit 82 counts the number of right block boundary flat pixels of such a block (N−1), and if the number is larger than the block boundary pixel detection number threshold value, the block (N
A right boundary processing determination signal that makes it effective to execute the boundary processing for the right block boundary flat pixel in (1) is generated. Since the intra-block filter application flag is invalid for the left block boundary pixel of the block (N), a left boundary processing determination signal that invalidates the boundary processing is generated.

(2) When the in-block filter application history of the block (N-1) is invalid and the in-block filter application flag of the block (N) is valid, the in-block flat portion pattern is referred to, and the block (N)
Of the left block boundary pixels, the left block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified, and is located at the position of the left block boundary flat pixel in the left block boundary code pattern of the block (N). It is checked whether or not the corresponding code and the code corresponding to the position between the left block boundary flat pixel and the block boundary pixel of the block (N-1) adjacent thereto in the block boundary code pattern are the same. When the signs are the same, the left block boundary flat pixel of the block (N) corresponding to the position has a pixel value such that the difference between the block boundaries becomes larger than that of the original image by the smoothing process of the in-block pixel filter means 10. take. The boundary pixel determining unit 82 counts the number of left block boundary flat pixels of such a block (N), and when the number is larger than the block boundary pixel detection number threshold value, the left block boundary pixel of the block (N) is determined. A left boundary processing determination signal that makes it effective to execute the boundary processing is generated. Since the intra-block filter application history is invalid for the right block boundary pixel (n-1) of the block (N-1), the right boundary processing determination signal that invalidates the boundary processing is generated.

(3) When both the in-block filter application history of the block (N-1) and the in-block filter application flag of the block (N) are valid, the block (N-1) around the right block boundary peripheral flat pattern is referred to. ) Of the right block boundary pixels, the right block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified, and the flat position pattern in the block is referred to to identify the left block boundary pixel of the block (N). At, the left block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified, and at the position where the right block boundary flat pixel and the left block boundary flat pixel are adjacent to each other across the block boundary, The block boundary code pattern at the corresponding position and the right block at the position corresponding to the right block boundary flat pixel And click boundary code patterns, and examines the left block boundary code pattern positions corresponding to the left block boundary flat pixel, the three codes to check whether all the same. When the signs are the same, the right block boundary flat pixel of the block (N−1) and the left block boundary flat pixel of the block (N) corresponding to the position are the original image by the smoothing process of the in-block pixel filter means 10. Pixel values are taken so that the difference between the block boundaries is larger than that of. In the boundary pixel determination means 82,
The number of the right block boundary flat pixels of the block (N-1) and the left block boundary flat pixel of the block (N) is counted, and if each number is larger than the block boundary pixel detection number threshold value, the block (N A right boundary processing determination signal and a left boundary processing determination signal that enable execution of boundary processing for the right block boundary flat pixel of (-1) and the left block boundary flat pixel of block (N) are generated.

In the boundary pixel processing means 13, based on the right boundary processing determination signal in the right boundary pixel selection means 20, the original image right block boundary read from the input image memory 1 for the right block boundary pixel for which the boundary processing is effective. The boundary pixel holding unit 11 selects the pixel data (n-1) and regards the right block boundary pixel for which the boundary processing is invalid.
The processed image right boundary pixel data (n-1 ') is selected and output to the image output means 14 as right block boundary output data. Similarly, the left boundary pixel selection means 21 selects the original image left block boundary pixel data (n) read from the input image memory 1 for the left block boundary pixel for which the boundary processing is effective, based on the left boundary processing determination signal. Then, the processed image left boundary pixel data (n ′) from the boundary pixel holding unit 11 is selected for the left block boundary pixel for which the boundary processing is invalid, and is output to the image output unit 14 as the left block boundary output data.

As described above, according to the fourth embodiment, the sign of the difference between pixels of the original images of the two adjacent blocks forming the block boundary, the result of determination as to whether or not the intra-block filtering process can be applied, and the intra-block flat portion. By using the information, it is inspected in advance whether or not the block boundary pixel can take a pixel value that makes the difference between pixels of the block boundary larger than that of the original image by the intra-block filtering process. When flat, if the number of such block boundary pixels exceeds a certain threshold given as the block boundary pixel detection count threshold, the original image instead of the intrablock filtered pixels for the block boundary pixels. By selecting the boundary pixel of, the difference value between pixels of the flat block boundary, which is easily visually noticeable when distortion occurs, becomes the original image. Base become not so it becomes possible to largely, it is possible to adjust the degree of the block boundary processing, thereby achieving a high display quality.

(Fifth Embodiment) FIG. 7 is a block diagram showing the arrangement of an image processing apparatus according to the fifth embodiment of the present invention. The image processing apparatus shown in FIG. 7 has the flat portion pattern holding means 9 and the boundary pixel determination means 12 shown in FIG.
Instead of the above, a flat portion pattern holding means 99 and a boundary pixel determination means 102 are provided, and further the inter-pixel difference value calculation means 9 is provided.
5 is provided. Other configurations are the same as those of the image processing apparatus shown in FIG.

The inter-pixel difference value calculation means 95 calculates the difference between the left block boundary pixel of the processing target block data read from the input image memory 1 and the adjacent pixel of the original image right block boundary pixel data of the adjacent block data. , As a block boundary difference value.

The flat spot pattern holding means 99 holds the flat spot pattern in the block around the right block boundary among the flat spot patterns in the block and outputs it as the flat spot pattern around the right block boundary.

The boundary pixel determining means 102 determines the left block boundary code pattern, the right block boundary code pattern, the block boundary code pattern, the in-block filter application flag, the in-block filter application history, the in-block flat location pattern, and the right block boundary peripheral flat. The processing for the boundary pixel between the block to be processed and the adjacent block is determined based on the location pattern, the flat location pattern in the block, the block boundary difference value, and the block boundary difference threshold, and the right boundary processing determination signal and the left boundary processing determination are performed. Generate a signal.

In the inter-pixel difference value calculating means 95, the adjacent blocks (N-
The original image right block boundary pixel data (n-1) of the block (N-1) output from the input image memory 1 by the boundary pixel memory address (n-1) of 1) and the address generating means 3 generate the same. The difference value between adjacent pixels is calculated for the left block boundary pixel of the processing target block image data (n) output from the input image memory 1 by the processing target block memory address (n) of the block (N) Boundary pixel determination means 102 as a difference value
Output to.

The flat portion pattern holding means 99 holds the flat portion inside block portion pattern (n) of the block (N) and the block inside flat portion pattern portions around the right block boundary for one block processing period. The held pattern is, when the block processing status N + 1 (processing target block = block N + 1, adjacent block = block N),
It is output to the boundary pixel determination means 102 as a pattern around the right block boundary of the adjacent block.

In the boundary pixel determining means 102, the block processing status N-1 (processing target block = block N-)
1, adjacent block = block N−2), the in-block filter application history (n−) of the block (N−1) generated by the in-block filter application determination unit 6 and held by the in-block filter application flag holding unit 8 1)
And either or both of the in-block filter application flags (n) of the block (N) from the in-block filter application determining means 6 are valid, the block processing status N-1 (processing target block = block N- 1, adjacent block = block N-2), the flat portion pattern holding means 99 generated by the flat portion inside block detecting means 7
A right block boundary peripheral flat portion pattern (n-1) of the block (N-1) held in the block and a block flat portion pattern (n) of the block (N) from the intra-block flat portion detecting means 7; , The block boundary difference value from the inter-pixel difference value calculating means 95, the right block boundary code pattern (n-1) of the block (N-1) from the inter-pixel difference code calculating means 4, and the block (N-1). And the left block boundary code pattern (n) of the block (N) with reference to the block boundary code pattern of the block boundary of the block (N), and the right block boundary pixel of the block (N-1) and the block (N) of the block (N). The boundary processing of the left block boundary pixel is determined.

In the following description, (1) block (N-
In-block filter application history (n-1) of 1) is valid, and in-block filter application flag (n) of block (N)
Is invalid, (2) If the in-block filter application history (n-1) of the block (N-1) is invalid and the in-block filter application flag (n) of the block (N) is valid, (3) ) The case where both the in-block filter application history (n-1) of the block (N-1) and the in-block filter application flag (n) of the block (N) are valid will be described separately.

(1) When the in-block filter application history (n-1) of the block (N-1) is valid and the in-block filter application flag (n) of the block (N) is invalid, the periphery of the right block boundary is flat. By referring to the location pattern, the right block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified among the right block boundary pixels of the block (N−1), and the right block boundary flat pixel is moved to the left. The pixel difference value between the right block boundary flat pixel and the left block boundary pixel of the block (N) adjacent to the right of the right block boundary flat pixel among the block boundary difference values that is continuously flat for a predetermined number or more is The second threshold is larger than the first threshold given as the block boundary difference threshold.
Is smaller than the threshold value of, the code corresponding to the position of the right block boundary flat pixel of the right block boundary code pattern (n-1) of the block (N-1) and the right block boundary flat of the block boundary code pattern. It is checked whether the code corresponding to the position between the pixel and the block boundary pixel of the block (N) adjacent thereto is the same. If the codes are the same, the block (N-1) corresponding to that position
The right-side block boundary flat pixel has a pixel value such that the difference in the block boundary becomes larger than that of the original image by the smoothing process of the in-block pixel filter means 10. The boundary pixel determination means 102 generates a right boundary processing determination signal that makes effective the boundary processing for the right block boundary flat pixel of the block (N−1). Since the in-block filter application flag (n) is invalid for the left block boundary pixel of the block (N), a left boundary processing determination signal that invalidates the boundary processing is generated.

(2) In-block filter application history (n-1) of block (N-1) is invalid and in-block filter application flag (n) of block (N) is valid. Reference and block (N)
Of the left block boundary pixels, a left block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified, and a predetermined number or more of the left block boundary flat pixels are continuously flat to the right from the left block boundary flat pixel, and Among the block boundary difference values, the inter-pixel difference value between the left block boundary flat pixel and the right block boundary pixel of the block (N−1) adjacent to the left of the left block boundary flat pixel is given as the block boundary difference threshold. If it is larger than the threshold value of 1 and smaller than the second threshold value, the code corresponding to the position of the left block boundary flat pixel in the left block boundary code pattern (n) of the block (N) and the block boundary code pattern The left block boundary flat pixel and the adjacent block (N-
It is checked whether or not the code corresponding to the position between the block boundary pixel of 1) is the same. When the signs are the same, the left block boundary flat pixel of the block (N) corresponding to the position has a pixel value such that the difference between the block boundaries becomes larger than that of the original image by the smoothing process of the in-block pixel filter means 10. take. In the boundary pixel determination means 102,
A left boundary processing determination signal that makes it effective to perform boundary processing on the left block boundary flat pixel of the block (N) is generated. Since the intra-block filter application history (n-1) is invalid for the right block boundary pixel of the block (N-1), the right boundary processing determination signal that invalidates the boundary processing is generated.

(3) When the in-block filter application history (n-1) of block (N-1) and the in-block filter application flag (n) of block (N) are both valid Flat pattern around the right block boundary Of the right block boundary pixels of the block (N-1), the right block boundary flat pixel to be filtered by the intra-block pixel filter means 10 is specified, and the intra-block flat portion pattern is referred to for the block (N When a left block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified among the left block boundary pixels in (4), and a predetermined number or more of them are continuously flat to the left from the right block boundary flat pixel. Or, if the left block boundary flat pixel is continuously flat to the right by a predetermined number or more, the right block boundary flat pixel and the left block boundary are flat. The block boundary difference value corresponding to a portion where the flat pixels are adjacent to each other across the block boundary is inspected, and the block boundary difference value is larger than the first threshold value given as the block boundary difference threshold value. If it is smaller than the threshold value, the block boundary code pattern at the position corresponding to the position and the right block boundary code pattern (n-1) at the position corresponding to the right block boundary flat pixel
Then, for the left block boundary code pattern (n) at the position corresponding to the left block boundary flat pixel, it is checked whether or not all these three codes are the same. When the signs are the same, the right block boundary flat pixel of the block (N−1) and the left block boundary flat pixel of the block (N) corresponding to the position are the original image by the smoothing process of the in-block pixel filter means 10. Pixel values are taken so that the difference between the block boundaries is larger than that of. Boundary pixel determination means 102
Then, the right boundary processing determination signal and the left boundary processing determination that enable the execution of the boundary processing on the right block boundary flat pixel of the block (N-1) and the left block boundary flat pixel of the block (N-1) are effective. Generate a signal.

In the boundary pixel processing means 13, based on the right boundary processing determination signal in the right boundary pixel selection means 20, the original image right block boundary read from the input image memory 1 for the right block boundary pixel for which the boundary processing is effective. The boundary pixel holding unit 11 selects the pixel data (n-1) and regards the right block boundary pixel for which the boundary processing is invalid.
The processed image right boundary pixel data (n-1 ') is selected and output to the image output means 14 as right block boundary output data. Similarly, the left boundary pixel selection means 21 selects the original image left block boundary pixel data (n) read from the input image memory 1 for the left block boundary pixel for which the boundary processing is effective, based on the left boundary processing determination signal. Then, the processed image left boundary pixel data (n ′) from the boundary pixel holding unit 11 is selected for the left block boundary pixel for which the boundary processing is invalid, and is output to the image output unit 14 as the left block boundary output data.

As described above, according to the fifth embodiment, the difference value between the block boundary pixels of the original images of the two adjacent blocks forming the block boundary, the sign of the pixel difference, and the intra-block filter application are applied. Using the determination result and the in-block flat portion information, it is inspected in advance whether or not the block boundary pixel can take a pixel value that makes the inter-pixel difference of the block boundary larger than the original image by the in-block filtering process, If the periphery of such a block boundary pixel is flat, and the difference value between the corresponding block boundary pixels is larger than the first threshold value given as the block boundary difference threshold value and smaller than the second threshold value. , About block boundary pixel By selecting the boundary pixel of the original image instead of the intra-block filter pixel, there is distortion at the block boundary of the original image. It is possible to check in advance whether or not to make the difference between pixels only when the block boundary is distorted and the block boundary is composed of a flat part where distortion due to intra-block filtering is easily noticeable. It is possible to prevent the image from becoming larger than the image, and it is possible to improve the image quality.

(Sixth Embodiment) FIG. 8 is a block diagram showing the arrangement of an image processing apparatus according to the sixth embodiment of the present invention. The image processing apparatus shown in FIG. 8 has the flat portion pattern holding means 9 and the boundary pixel determination means 12 shown in FIG.
Instead, a flat portion pattern holding unit 119 and a boundary pixel determination unit 122 are provided, and further an inter-pixel difference value calculation unit 115 is provided. Other configurations are the same as those of the image processing apparatus shown in FIG.

The inter-pixel difference value calculation means 115 calculates the difference between the left block boundary pixel of the processing target block data read from the input image memory 1 and the adjacent pixel of the original image right block boundary pixel data of the adjacent block data. ,
Output as a block boundary difference value.

The flat spot pattern holding means 119 holds the flat spot pattern in the block around the right block boundary among the flat spot patterns in the block and outputs it as the flat spot pattern around the right block boundary.

The boundary pixel determination means 122 determines the left block boundary code pattern, the right block boundary code pattern, the block boundary code pattern, the in-block filter application flag, the in-block filter application history, the in-block flat location pattern, and the right block boundary peripheral flatness. Based on the location pattern, the block boundary pixel detection number threshold value, the block boundary difference value, and the block boundary difference threshold value, the processing for the boundary pixel between the target block and the adjacent block is determined, and the right boundary processing determination signal and A left boundary processing determination signal is generated.

In the inter-pixel difference value calculating means 115, the adjacent blocks (N-
The original image right block boundary pixel data (n-1) of the block (N-1) output from the input image memory 1 by the boundary pixel memory address (n-1) of 1) and the address generating means 3 generate the same. The difference value between adjacent pixels is calculated for the left block boundary pixel of the processing target block image data (n) output from the input image memory 1 by the processing target block memory address (n) of the block (N) Boundary pixel determination means 122 as a difference value
Output to.

The flat portion pattern holding means 119 holds the flat portion inside block portion pattern (n) of the block (N) on the right block boundary and its periphery for one block processing period. The held pattern is, when the block processing status N + 1 (processing target block = block N + 1, adjacent block = block N),
The pattern is output to the boundary pixel determining means 122 as a flat pattern around the right block boundary of the adjacent block.

In the boundary pixel determining means 122, the block processing status N-1 (processing target block = block N-
1, adjacent block = block N−2), the in-block filter application history of the block (N−1) generated by the in-block filter application determination means 6 and held in the in-block filter application flag holding means 8, and the block When either or both of the block internal filter application flags of the block (N) from the internal filter application determining means 6 are valid, the block processing status N-1 (processing target block = block N-1, adjacent block = block) At the time of (N-2), the flat portion pattern around the right block boundary (n-1) of the block (N-1) which is generated by the in-block flat portion detecting means 7 and held by the flat portion pattern holding means 119 and the inside of the block. In-block flat part pattern (n) of the block (N) from the flat part detecting means 7 and the inter-pixel difference value And block border difference value from the detecting means 115, the right block boundary code patterns of the block (N-1) from the pixel difference codes calculation means 4 (n-1)
And the block boundary code pattern of the block boundary between the block (N-1) and the block (N) and the left block boundary code pattern of the block (N) are referred to.
The boundary processing of the right block boundary pixel of 1) and the left block boundary pixel of the block (N) is determined.

In the following description, (1) block (N-
When the in-block filter application history of 1) is valid and the in-block filter application flag of block (N) is invalid, (2) the in-block filter application history of block (N-1) is invalid and the block (N) of block (N) is When the in-block filter application flag is valid, (3) block (N-1)
The in-block filter application history and the in-block filter application flag of block (N) will be separately described.

(1) When the in-block filter application history of block (N-1) is valid and the in-block filter application flag of block (N) is invalid, the right block boundary peripheral flat portion pattern is referred to, and the block ( A right block boundary flat pixel to be filtered by the intra-block pixel filter means 10 is specified among the N-1) right block boundary pixels, and a predetermined number or more of them are continuously flattened to the left from the right block boundary flat pixel. And the inter-pixel difference value between the right block boundary flat pixel and the left block boundary pixel of the block (N) adjacent to the right of the right block boundary flat pixel among the block boundary difference values is given as the block boundary difference threshold value. Greater than the first threshold that is
Is smaller than the threshold value of, the code corresponding to the position of the right block boundary flat pixel of the right block boundary code pattern (n-1) of the block (N-1) and the right block boundary flat of the block boundary code pattern. It is checked whether the code corresponding to the position between the pixel and the block boundary pixel of the adjacent block (N) is the same. If the signs are the same, the right block boundary flat pixel of the block (N-1) corresponding to that position is a pixel whose difference in block boundary becomes larger than that of the original image by the smoothing process of the in-block pixel filter means 10. Take a value. The boundary pixel determination unit 122 counts the number of right block boundary flat pixels of such a block (N−1), and if the number is larger than the block boundary pixel detection number threshold value, the block (N−).
A right boundary processing determination signal that makes it effective to execute the boundary processing for the right block boundary flat pixel in 1) is generated. Since the intra-block filter application flag is invalid for the left block boundary pixel of the block (N), a left boundary processing determination signal that invalidates the boundary processing is generated.

(2) When the in-block filter application history of the block (N-1) is invalid and the in-block filter application flag of the block (N) is valid, the in-block flat portion pattern is referred to, and the block (N)
Of the left block boundary pixels, a left block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified, and a predetermined number or more of the left block boundary flat pixels are continuously flat to the right from the left block boundary flat pixel, and Among the block boundary difference values, the inter-pixel difference value between the left block boundary flat pixel and the right block boundary pixel of the block (N−1) adjacent to the left of the left block boundary flat pixel is given as the block boundary difference threshold. If it is larger than the threshold value of 1 and smaller than the second threshold value, the code corresponding to the position of the left block boundary flat pixel in the left block boundary code pattern of the block (N) and the left block of the block boundary code pattern Check whether the code corresponding to the position between the boundary flat pixel and the block boundary pixel of the block (N-1) adjacent thereto is the same. That. When the signs are the same, the left block boundary flat pixel of the block (N) corresponding to the position has a pixel value such that the difference between the block boundaries becomes larger than that of the original image by the smoothing process of the in-block pixel filter means 10. take. The boundary pixel determination unit 122 counts the number of left block boundary flat pixels of such a block (N), and when the number is larger than the block boundary pixel detection number threshold value, the left block boundary pixel of the block (N) is determined. A left boundary processing determination signal that makes it effective to execute the boundary processing is generated. Since the intra-block filter application history is invalid for the right block boundary pixel (n-1) of the block (N-1), the right boundary processing determination signal that invalidates the boundary processing is generated.

(3) When both the intra-block filter application history of block (N-1) and the intra-block filter application flag of block (N) are valid, the block (N
-1) The right block boundary pixels of the block (N) are identified by specifying the right block boundary flat pixels to be filtered by the in-block pixel filter means 10 among the right block boundary pixels of -1) and referring to the in-block flat portion pattern. If a left block boundary flat pixel to be filtered by the in-block pixel filter means 10 is specified, and if it is continuously flat for a predetermined number of times or more to the left from the right block boundary flat pixel, or a left block boundary flat pixel If the right block boundary flat pixel and the left block boundary flat pixel are adjacent to each other across the block boundary when they are continuously flat for a predetermined number of times to the right, the block boundary difference value is inspected and If the difference value is greater than a first threshold and less than a second threshold given as a block boundary difference threshold, the right block Block boundary flat pixel and left block boundary When a flat pixel is adjacent with a block boundary in between, the block boundary code pattern at the position corresponding to that position and the right block boundary at the position corresponding to the right block boundary flat pixel Regarding the code pattern and the left block boundary code pattern at the position corresponding to the left block boundary flat pixel,
Check if all three codes are the same.
When the signs are the same, the right block boundary flat pixel of the block (N−1) and the left block boundary flat pixel of the block (N) corresponding to the position are the original image by the smoothing process of the in-block pixel filter means 10. Pixel values are taken so that the difference between the block boundaries is larger than that of. In the boundary pixel determining means 122, such a block (N-1)
The right block boundary flat pixels of the block (N) and the left block boundary flat pixels of the block (N) are counted, and when the respective numbers are larger than the block boundary pixel detection number threshold value, the right block boundary flat pixels of the block (N-1) And a right boundary processing determination signal and a left boundary processing determination signal that enable the boundary processing to be performed on the left block boundary flat pixel of the block (N).

In the boundary pixel processing means 13, based on the right boundary processing determination signal in the right boundary pixel selection means 20, the original image right block boundary read out from the input image memory 1 for the right block boundary pixel for which the boundary processing is effective. The boundary pixel holding unit 11 selects the pixel data (n-1) and regards the right block boundary pixel for which the boundary processing is invalid.
The processed image right boundary pixel data (n-1 ') is selected and output to the image output means 14 as right block boundary output data. Similarly, the left boundary pixel selection means 21 selects the original image left block boundary pixel data (n) read from the input image memory 1 for the left block boundary pixel for which the boundary processing is effective, based on the left boundary processing determination signal. Then, the processed image left boundary pixel data (n ′) from the boundary pixel holding unit 11 is selected for the left block boundary pixel for which the boundary processing is invalid, and is output to the image output unit 14 as the left block boundary output data.

As described above, according to the sixth embodiment, the sign of the pixel difference between the original images of the two adjacent blocks forming the block boundary, the result of determination as to whether or not the intra-block filtering process can be applied, and the intra-block flat portion. By using the information, it is inspected in advance whether or not the block boundary pixel can take a pixel value that makes the difference between pixels of the block boundary larger than that of the original image by the intra-block filtering process. The number of such block boundary pixels that are flat and have a difference value between the corresponding block boundary pixels that is greater than a first threshold value that is given as a block boundary difference threshold value and that is less than a second threshold value. Is greater than a predetermined threshold given as the block boundary pixel detection count threshold, the block boundary pixel is subjected to the intra-block filter processing. By selecting the boundary pixels of the original image instead of the pixels, it is possible to check in advance whether or not there is distortion at the block boundary of the original image. It is possible to prevent the pixel-to-pixel difference value of the block boundary from becoming larger than that of the original image only for the block boundary formed by a flat part that is visually noticeable, and to adjust the degree of block boundary processing. It is possible to improve the image quality.

(Seventh Embodiment) FIG. 9 is a block diagram showing the arrangement of an image processing apparatus according to the seventh embodiment of the present invention. The image processing apparatus shown in FIG. 9 includes the flat portion pattern holding means 9, the intra-block pixel filter means 10, the boundary pixel holding means 11, and the boundary pixel determination means 12 shown in FIG.
In place of the boundary pixel processing means 13, a flat portion pattern holding means 139, an in-block pixel filter means 140, a boundary peripheral pixel holding means 141, a boundary pixel determination means 142, and a boundary pixel processing means 143 are further provided, and an inter-pixel difference value is provided. The calculation means 135 is provided. Other configurations are the same as those of the image processing apparatus shown in FIG.

The inter-pixel difference value calculating means 135 calculates the difference between the left block boundary pixel of the processing target block data read from the input image memory 1 and the adjacent pixel of the original image right block boundary pixel data of the adjacent block data. ,
Output as a block boundary difference value.

The flat portion pattern holding means 139 holds the flat portion in the block around the right block boundary among the flat portion patterns in the block and outputs it as the right flat portion around the right block boundary.

The in-block pixel filter means 140 performs a smoothing process on the block image data to be processed read from the input image memory 1 based on the in-block filter application flag and the in-block flat spot pattern.

The boundary peripheral pixel holding means 141 holds the right block boundary peripheral pixels of the output of the in-block pixel filter means 140.

The boundary pixel determining means 142 determines the left block boundary code pattern, the right block boundary code pattern, the block boundary code pattern, the in-block filter application flag, the in-block filter application history, the in-block flat location pattern, and the right block boundary peripheral flat. The processing for the boundary pixels of the block to be processed and the adjacent block is determined based on the location pattern, the block boundary difference value, and the block boundary difference threshold value, and the right boundary processing determination signal and the left boundary processing determination signal are generated.

FIG. 10 is a block diagram showing the internal structure of the boundary pixel processing means 143 shown in FIG. As shown in FIG. 10, the boundary pixel processing unit 143 includes a right boundary pixel filter unit 150, a right boundary pixel selection unit 151, a left boundary pixel filter unit 152, and a left boundary pixel selection unit 15.
Including 3 and. The right boundary pixel filter means 150 performs a filtering process using the processed image right block boundary peripheral pixel data and the processed image left block boundary peripheral pixel data. The right boundary pixel selection means 151 selectively outputs the output from the right boundary pixel filter means 150 and the original image right block boundary pixel data based on the right boundary processing determination signal. The left boundary pixel filter means 152 performs a filtering process using the processed image left block boundary peripheral pixel data and the processed image right block boundary peripheral pixel data. Left boundary pixel selection means 1
53 selectively outputs the output from the left boundary pixel filter means 152 and the original image left block boundary pixel data based on the left boundary processing determination signal.

In the inter-pixel difference value calculating means 135, the adjacent block (N-
The original image right block boundary pixel data (n-1) of the block (N-1) output from the input image memory 1 by the boundary pixel memory address (n-1) of 1) and the address generating means 3 generate the same. The difference value between adjacent pixels is calculated for the left block boundary pixel of the processing target block image data (n) output from the input image memory 1 by the processing target block memory address (n) of the block (N) Boundary pixel determination means 142 as a difference value
Output to.

The flat part pattern holding means 139 holds the flat part in-block pattern on the right block boundary and its periphery in the intra-block flat part pattern (n) of the block (N) for one block processing period. The held pattern is, when the block processing status N + 1 (processing target block = block N + 1, adjacent block = block N),
The pattern is output to the boundary pixel determining means 142 as a flat pattern around the right block boundary of the adjacent block.

In the block pixel filter means 140,
If the in-block filter application flag (n) of the block (N) generated by the in-block filter application determination means 6 is valid, the block of the block (N) generated by the in-block flat portion detection means 7 In accordance with the inner flat portion pattern (n), the smoothing process is performed by the flat pixels in the block image data to be processed (n) and the three horizontally adjacent two pixels. When the in-block filter application flag (n) of the block (N) generated by the in-block filter application determination unit 6 is invalid, the block image data to be processed (n) is processed regardless of the state of the in-block flat portion pattern. The smoothing process for is not performed. Further, regardless of whether or not the smoothing process is performed, the right block boundary peripheral pixels of the block (N) are stored in the boundary peripheral pixel holding means 141, and the left block boundary peripheral pixels of the block (N) are processed image left block boundary peripheral pixel data. (N ') is output to the boundary pixel processing means 143, and the non-block boundary peripheral pixels of the block (N) are output to the image output means 14 as processed image non-block boundary peripheral pixel data (n').

The boundary peripheral pixel holding means 141 holds the right block boundary peripheral pixels of the block (N) output from the in-block pixel filter means 140 for one block processing period. When the block processing status is N + 1 (processing target block = block N + 1, adjacent block = block N), the held data is the boundary pixel processing means 14 as the processed image right block boundary peripheral pixel data of the adjacent block.
3 is output.

In the boundary pixel determining means 142, the block processing status N-1 (processing target block = block N-
1, adjacent block = block N−2), the in-block filter application history (n−) of the block (N−1) generated by the in-block filter application determination unit 6 and held by the in-block filter application flag holding unit 8 1)
And either or both of the in-block filter application flags (n) of the block (N) from the in-block filter application determining means 6 are valid, the block processing status N-1 (processing target block = block N- 1, adjacent block = block N-2), the flat portion pattern holding means 13 generated by the flat portion inside block detecting means 7
The right block boundary peripheral flat portion pattern (n-1) of the block (N-1) held in 9 and the block inner flat portion pattern (n) of the block (N) from the intra-block flat portion detection means 7 And the inter-pixel difference value calculation means 135
From the inter-pixel difference code calculation unit 4, the right block boundary code pattern (n-1) of the block (N-1), and the block boundary between the block (N-1) and the block (N). Block boundary code pattern of
With reference to the left block boundary code pattern (n) of the block (N), the boundary processing of the right block boundary pixel of the block (N-1) and the left block boundary pixel of the block (N) is determined.

In the following description, (1) block (N-
In-block filter application history (n-1) of 1) is valid, and in-block filter application flag (n) of block (N)
Is invalid, (2) If the in-block filter application history (n-1) of the block (N-1) is invalid and the in-block filter application flag (n) of the block (N) is valid, (3) ) The case where both the in-block filter application history (n-1) of the block (N-1) and the in-block filter application flag (n) of the block (N) are valid will be described separately.

(1) When the in-block filter application history (n-1) of the block (N-1) is valid and the in-block filter application flag (n) of the block (N) is invalid, the periphery of the right block boundary is flat. By referring to the location pattern, the right block boundary flat pixel to be filtered by the in-block pixel filter means 140 is specified from the right block boundary flat pixels of the block (N−1), and the right block boundary flat pixel is moved to the left. The pixel difference value between the right block boundary flat pixel and the left block boundary pixel of the block (N) adjacent to the right of the right block boundary flat pixel among the block boundary difference values that is continuously flat for a predetermined number or more is The right block boundary code of the block (N-1) if it is larger than a first threshold and smaller than a second threshold given as a block boundary difference threshold A code corresponding to the position of the right block boundary flat pixel in the turn (n-1) and a position between the right block boundary flat pixel and the block boundary pixel of the block (N) adjacent to the right block boundary code pattern in the block boundary code pattern. Check whether the corresponding codes are the same. If the codes are the same, the block (N-1) corresponding to that position
The right-side block boundary flat pixel has a pixel value such that the difference between the block boundaries becomes larger than that of the original image by the smoothing processing by the in-block pixel filter means 140. The boundary pixel determining unit 142 generates a right boundary processing determination signal that makes it effective to perform the boundary processing on the right block boundary flat pixel of the block (N−1). Since the in-block filter application flag (n) is invalid for the left block boundary pixel of the block (N), a left boundary processing determination signal that invalidates the boundary processing is generated.

(2) In-block filter application history (n-1) of block (N-1) is invalid and in-block filter application flag (n) of block (N) is valid. Reference and block (N)
Of the left block boundary pixels, a left block boundary flat pixel to be filtered by the in-block pixel filter means 140 is specified, and a predetermined number or more are continuously flat to the right from the left block boundary flat pixel, and Among the block boundary difference values, the inter-pixel difference value between the left block boundary flat pixel and the right block boundary pixel of the block (N−1) adjacent to the left of the left block boundary flat pixel is given as the block boundary difference threshold. If it is larger than the threshold value of 1 and smaller than the second threshold value, the code corresponding to the position of the left block boundary flat pixel in the left block boundary code pattern (n) of the block (N) and the block boundary code pattern The left block boundary flat pixel and the adjacent block (N
It is checked whether the code corresponding to the position between the block boundary pixel of -1) is the same. When the codes are the same, the left block boundary flat pixel of the block (N) corresponding to the position has a pixel value such that the difference between the block boundaries becomes larger than that of the original image by the smoothing process of the in-block pixel filter means 140. take. The boundary pixel determination means 142 generates a left boundary processing determination signal that makes it effective to perform the boundary processing on the left block boundary flat pixels of the block (N). For the right block boundary pixel of the block (N-1), the in-block filter application history (n-
Since 1) is invalid, a right boundary processing determination signal that invalidates the execution of boundary processing is generated.

(3) When the in-block filter application history (n-1) of the block (N-1) and the in-block filter application flag (n) of the block (N) are both valid, the flat block pattern around the right block boundary Of the right block boundary pixels of the block (N−1), the right block boundary flat pixel to be filtered by the in-block pixel filter means 140 is specified, and the block (N) is referred to by the in-block flat portion pattern. When the left block boundary flat pixel to be filtered by the in-block pixel filter unit 140 is specified among the left block boundary pixels in (4), and a predetermined number or more are flat to the left from the right block boundary flat pixel. Or, if the left block boundary flat pixel is flat to the right for a predetermined number of times or more, the right block boundary flat pixel and the left block flat pixel are The block boundary difference value corresponding to a position where the boundary flat pixels are adjacent to each other across the block boundary is inspected, and the block boundary difference value is larger than the first threshold value given as the block boundary difference threshold value. If it is smaller than the threshold value, the block boundary code pattern at the position corresponding to the position and the right block boundary code pattern (n-
1) and the left block boundary code pattern (n) at the position corresponding to the left block boundary flat pixel, these 3
Check if all two signs are the same. If the codes are the same, the block (N-1) corresponding to that position
The right block boundary flat pixel of and the left block boundary flat pixel of the block (N) are in-block pixel filter means 1.
By the smoothing process of 40, the pixel value is set so that the difference between the block boundaries becomes larger than that of the original image. In the boundary pixel determining means 142, a right boundary processing determination signal that validates the boundary processing for the right block boundary flat pixel of the block (N−1) and the left block boundary flat pixel of the block (N−1). And a left boundary processing determination signal is generated.

In the boundary pixel processing means 143, based on the right boundary processing determination signal in the right boundary pixel selection means 151,
The output of the right boundary pixel filter means 150 is selected for the right block boundary pixels for which the boundary processing is valid, and the processed image right boundary from the boundary peripheral pixel holding means 141 is selected for the right block boundary pixels for which the boundary processing is invalid. The pixel data (n-1 ') is selected and output to the image output means 14 as right block boundary output data. Similarly, the left boundary pixel selection means 153 selects the output of the left boundary pixel filter means 152 for the left block boundary pixels for which the boundary processing is effective, based on the left boundary processing determination signal,
The processed image left block boundary pixel data (n ′) from the in-block pixel filter means 140 is selected for the left block boundary pixel for which the boundary processing is invalid, and is output to the image output means 14 as left block boundary output data.

As described above, according to the seventh embodiment, the difference value between the block boundary pixels of the original images of the two adjacent blocks forming the block boundary, the sign of the pixel difference, and the intra-block filter processing application are performed. Using the determination result and the in-block flat portion information, it is inspected in advance whether or not the block boundary pixel can take a pixel value that makes the inter-pixel difference of the block boundary larger than the original image by the in-block filtering process, If the periphery of such a block boundary pixel is flat, and the difference value between the corresponding block boundary pixels is larger than the first threshold value given as the block boundary difference threshold value and smaller than the second threshold value. , About block boundary pixel By selecting the boundary pixel of the original image instead of the intra-block filter pixel, there is distortion at the block boundary of the original image. It is possible to check in advance whether or not to do so, and the boundary pixel of the adjacent block is determined as the boundary pixel of the adjacent block only for the block boundary where the distortion exists and the flat boundary where the distortion due to the intra-block filtering process is visually noticeable. Filtering processing can be performed, and high image quality can be achieved.

(Eighth Embodiment) FIG. 11 is a block diagram showing the arrangement of an image processing apparatus according to the eighth embodiment of the present invention. The image processing apparatus shown in FIG. 11 is flat in place of the flat portion pattern holding means 9, the in-block pixel filter means 10, the boundary pixel holding means 11, the boundary pixel determination means 12, and the boundary pixel processing means 13 shown in FIG. Local pattern holding means 169 and in-block pixel filtering means 170
And boundary peripheral pixel holding means 171 and boundary pixel determination means 17
2 and the boundary pixel processing means 143, and further the inter-pixel difference value calculating means 155. Other configurations are the same as those of the image processing apparatus shown in FIG.

The inter-pixel difference value calculating means 155 calculates the difference between the left block boundary pixel of the processing target block data read from the input image memory 1 and the adjacent pixel of the original image right block boundary pixel data of the adjacent block data. ,
Output as a block boundary difference value.

The in-block pixel filter means 170 performs a smoothing process on the block image data to be processed read from the input image memory 1 based on the in-block filter application flag and the in-block flat spot pattern.

The boundary peripheral pixel holding means 171 holds the right block boundary peripheral pixels of the output of the in-block pixel filter means 170.

The flat part pattern holding means 169 holds the intra-block flat part pattern around the right block boundary among the intra-block flat part patterns and outputs it as the right block boundary peripheral flat part pattern.

The boundary pixel determination means 172 determines the left block boundary code pattern, the right block boundary code pattern, the block boundary code pattern, the in-block filter application flag, the in-block filter application history, the in-block flat location pattern, and the right block boundary peripheral flat. Based on the location pattern, the block boundary pixel detection number threshold value, the block boundary difference value, and the block boundary difference threshold value, the processing for the boundary pixel between the target block and the adjacent block is determined, and the right boundary processing determination signal and A left boundary processing determination signal is generated.

In the inter-pixel difference value calculating means 155, the adjacent blocks (N-
1) The original pixel right block boundary pixel data (n-1) of the block (N-1) output from the input image memory 1 by the boundary pixel memory address (n-1) of 1), and the address generation means 3. Block block (N) processing target block memory address (n) outputs the processing target block image data (n) left block boundary pixel, calculates the difference value between adjacent pixels, and determines the block boundary. Boundary pixel determination means 172 as a difference value
Output to.

The flat portion pattern holding means 169 holds the flat portion in-block pattern on the right block boundary and its periphery in the in-block flat portion pattern (n) of the block (N) for one block processing period. The held pattern is, when the block processing status N + 1 (processing target block = block N + 1, adjacent block = block N),
It is output to the boundary pixel determination means 172 as a flat portion around the right block boundary of the adjacent block.

In the block pixel filter means 170,
If the in-block filter application flag (n) of the block (N) generated by the in-block filter application determination means 6 is valid, the block of the block (N) generated by the in-block flat portion detection means 7 In accordance with the inner flat portion pattern (n), the smoothing process is performed by the flat pixels in the block image data to be processed (n) and the three horizontally adjacent two pixels. When the in-block filter application flag (n) of the block (N) generated by the in-block filter application determination unit 6 is invalid, the block image data to be processed (n) is processed regardless of the state of the in-block flat portion pattern. The smoothing process for is not performed. Further, regardless of whether or not the smoothing process is performed, the right block boundary peripheral pixels of the block (N) are stored in the boundary peripheral pixel holding means 171, and the left block boundary peripheral pixels of the block (N) are processed image left block boundary peripheral pixel data. (N ') is output to the boundary pixel processing means 143, and the non-block boundary peripheral pixels of the block (N) are output to the image output means 14 as processed image non-block boundary peripheral pixel data (n').

The boundary peripheral pixel holding means 171 holds the right block boundary peripheral pixels of the block (N) output from the in-block pixel filter means 170 for one block processing period. The held data is output to the boundary pixel processing unit 143 as peripheral pixels of the processed image right block boundary of the adjacent block when the block processing status N + 1 (processing target block = block N + 1, adjacent block = block N).

In the boundary pixel determining means 172, the block processing status N-1 (processing target block = block N-
1, adjacent block = block N−2), the in-block filter application history of the block (N−1) generated by the in-block filter application determination means 6 and held in the in-block filter application flag holding means 8, and the block When either or both of the block internal filter application flags of the block (N) from the internal filter application determining means 6 are valid, the block processing status N-1 (processing target block = block N-1, adjacent block = block) At the time of N-2), the right block boundary peripheral flat portion pattern (n-1) of the block (N-1) generated by the in-block flat portion detecting means 7 and held by the flat portion pattern holding means 169, and the inside of the block In-block flat part pattern (n) of the block (N) from the flat part detecting means 7 and the inter-pixel difference value And block border difference value from the detecting means 155, the right block boundary code patterns of the block (N-1) from the pixel difference codes calculation means 4 (n-1)
And the block boundary code pattern of the block boundary between the block (N-1) and the block (N) and the left block boundary code pattern of the block (N) are referred to.
The boundary processing of the right block boundary pixel of 1) and the left block boundary pixel of the block (N) is determined.

In the following description, (1) block (N-
When the in-block filter application history of 1) is valid and the in-block filter application flag of block (N) is invalid, (2) the in-block filter application history of block (N-1) is invalid and the block (N) of block (N) is When the in-block filter application flag is valid, (3) block (N-1)
The in-block filter application history and the in-block filter application flag of block (N) will be separately described.

(1) When the in-block filter application history of the block (N-1) is valid and the in-block filter application flag of the block (N) is invalid, the right block boundary peripheral flat pattern is referred to and the block ( A right block boundary flat pixel to be filtered by the intra-block pixel filter means 170 is specified from among the N-1) right block boundary pixels, and a predetermined number or more of them are continuously flattened to the left from the right block boundary flat pixel. And the inter-pixel difference value between the right block boundary flat pixel and the left block boundary pixel of the block (N) adjacent to the right of the right block boundary flat pixel among the block boundary difference values is given as the block boundary difference threshold value. Is greater than the first threshold and less than the second threshold, the right block boundary code pattern (n-1) of block (N-1). The code corresponding to the position of the right block boundary flat pixel is the same as the code corresponding to the position between the right block boundary flat pixel and the block boundary pixel of the adjacent block (N) in the block boundary code pattern. Inspect for existence. If the codes are the same, the block (N-1) corresponding to that position
The right block boundary flat pixel has a pixel value such that the difference between the block boundaries becomes larger than that of the original image by the smoothing process by the in-block pixel filter means 170. The boundary pixel determination means 172 counts the number of right block boundary flat pixels of such a block (N−1), and when the number is larger than the block boundary pixel detection number threshold value, the right of the block (N−1). A right boundary processing determination signal is generated that makes it effective to perform boundary processing for block boundary flat pixels.
Since the intra-block filter application flag is invalid for the left block boundary pixel of the block (N), a left boundary processing determination signal that invalidates the boundary processing is generated.

(2) When the in-block filter application history of the block (N-1) is invalid and the in-block filter application flag of the block (N) is valid, the in-block flat portion pattern is referred to, and the block (N)
Of the left block boundary pixels, the left block boundary flat pixel to be filtered by the in-block pixel filter unit 170 is specified, and the left block boundary flat pixel is continuously flat to the right by a predetermined number or more, and Among the block boundary difference values, the inter-pixel difference value between the left block boundary flat pixel and the right block boundary pixel of the block (N−1) adjacent to the left of the left block boundary flat pixel is given as the block boundary difference threshold. If it is larger than the threshold value of 1 and smaller than the second threshold value, the code corresponding to the position of the left block boundary flat pixel in the left block boundary code pattern of the block (N) and the left block of the block boundary code pattern Boundary flat pixel and adjacent block (N-1)
It is checked whether the code corresponding to the position between the block boundary pixel and the block boundary pixel is the same. When the signs are the same, the left block boundary flat pixel of the block (N) corresponding to that position has a pixel value such that the difference between the block boundaries becomes larger than that of the original image by the smoothing process of the in-block pixel filter means 170. take. The boundary pixel determining means 172 counts the number of left block boundary flat pixels of the block (N), and when the number is larger than the block boundary pixel detection count threshold value, the left block boundary pixel of the block (N). A left boundary processing determination signal that validates the boundary processing is generated. Since the intra-block filter application history is invalid for the right block boundary pixel (n-1) of the block (N-1), the right boundary processing determination signal that invalidates the boundary processing is generated.

(3) When both the intra-block filter application history of block (N-1) and the intra-block filter application flag of block (N) are valid, the block (N) is referenced by referring to the flat pattern around the right block boundary.
-1) The right block boundary pixels of the block (N) are identified by identifying the right block boundary flat pixels to be filtered by the in-block pixel filter means 170 among the right block boundary pixels of -1) and referring to the in-block flat portion pattern. If a left block boundary flat pixel to be filtered by the in-block pixel filter means 170 is specified, and if a predetermined number of consecutive left flat pixels from the right block boundary flat pixel, or a left block boundary flat pixel If the right block boundary flat pixel and the left block boundary flat pixel are adjacent to each other across the block boundary when there is a predetermined number of consecutive flats to the right, the block boundary difference value is inspected and If the difference value is greater than a first threshold and less than a second threshold given as a block boundary difference threshold, A block boundary code pattern at a position corresponding to a position where a block boundary flat pixel and a left block boundary flat pixel are adjacent to each other across a block boundary, and a right block boundary code at a position corresponding to a right block boundary flat pixel. For the pattern and the left block boundary code pattern at the position corresponding to the left block boundary flat pixel, it is checked whether all these three codes are the same. When the signs are the same, the right block boundary flat pixel of the block (N-1) and the left block boundary flat pixel of the block (N) corresponding to the position are the original image by the smoothing process of the in-block pixel filter means 170. Pixel values are taken so that the difference between the block boundaries is larger than that of. The boundary pixel determination means 172 uses such a block (N-
1) Count the number of right block boundary flat pixels and the number of left block boundary flat pixels of block (N). If the number of pixels is greater than the block boundary pixel detection number threshold value, the right block boundary of block (N-1) Border pixel and left block boundary of block (N) The right border processing determination signal and the left border processing determination signal that enable the implementation of the border processing for the flat pixel are generated.

In the boundary pixel processing means 143, based on the right boundary processing determination signal in the right boundary pixel selection means 151,
The output of the right boundary pixel filter means 150 is selected for the right block boundary pixel for which the boundary processing is valid, and the processed image right boundary from the boundary peripheral pixel holding means 171 is selected for the right block boundary pixel for which the boundary processing is invalid. The pixel data (n-1 ') is selected and output to the image output means 14 as right block boundary output data. Similarly, the left boundary pixel selection means 153 selects the output of the left boundary pixel filter means 152 for the left block boundary pixels for which the boundary processing is effective, based on the left boundary processing determination signal,
The processed image left block boundary pixel data (n ′) from the in-block pixel filter means 170 is selected for the left block boundary pixel for which the boundary processing is invalid, and is output to the image output means 14 as left block boundary output data.

As described above, according to the eighth embodiment, the sign of the pixel difference between the original images of the two adjacent blocks forming the block boundary, the result of determination as to whether or not the intra-block filtering process is applicable, and the intra-block flat portion are obtained. By using the information, it is inspected in advance whether or not the block boundary pixel can take a pixel value that makes the inter-pixel difference of the block boundary larger than the original image by the intra-block filtering process, and the periphery of such a block boundary pixel is The number of such block boundary pixels that are flat and have a difference value between corresponding block boundary pixels that is greater than a first threshold value that is given as a block boundary difference threshold value and that is less than a second threshold value. Is greater than a predetermined threshold given as the block boundary pixel detection count threshold, the block boundary pixel is subjected to the intra-block filter processing. By selecting the boundary pixels of the original image instead of the pixels, it becomes possible to check in advance whether or not there is distortion at the block boundary of the original image. It becomes possible to carry out the filtering process with the boundary pixels of the adjacent blocks only for the block boundary constituted by the flat part which is visually conspicuous, and it is possible to adjust the degree of the block boundary processing.
Higher image quality can be achieved.

In the description of the first to eighth embodiments, horizontal mosquito distortion reduction and block N are performed.
Although the operation in the processing for the boundary pixel between -1 and the block N has been described, it goes without saying that it is also effective in the vertical direction.

[0143]

According to the image processing apparatus of the present invention,
An in-block filter application flag that is a determination result of whether to apply in-block filtering processing of an adjacent block and an in-block flat portion pattern that is an in-block flat portion detection result are obtained by the in-block filter application determination means and the in-block filter information holding means. By doing so, the block to be subjected to the intra-block filter processing in the intra-block pixel filter means and the block boundary flat pixel in which the pixel value may vary due to the filter processing are recognized, and the block boundary flat pixel and the pixel between the adjacent pixel It is preliminarily checked whether or not the boundary pixel of the block can take a pixel value that makes the inter-pixel difference of the block boundary larger than that of the original image by the intra-block filter processing by obtaining the code of the difference between And determine the processing for border pixels. In it is possible to reduce the adverse effect to the block boundaries of the mosquito strain relief filter.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of boundary pixel processing means shown in FIG.

FIG. 3 is a diagram showing a size of one block and a reading order of block image data.

FIG. 4 is a block diagram showing a configuration of an image processing apparatus according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of an image processing apparatus according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of an image processing apparatus according to a fourth embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of an image processing apparatus according to a fifth embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of an image processing apparatus according to a sixth embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of an image processing apparatus according to a seventh embodiment of the present invention.

10 is a block diagram showing an internal configuration of the boundary pixel processing means shown in FIG.

FIG. 11 is a block diagram showing a configuration of an image processing device according to an eighth embodiment of the present invention.

FIG. 12 is a diagram for explaining conventional mosquito distortion reduction filter processing.

[Explanation of symbols]

1 Input Image Memory 2 Block Number Counter 3 Address Generation Means 4 Pixel Difference Code Calculation Means 95, 115, 135, 155 Pixel Difference Value Calculation Means 6 In-block Filter Application Determining Means 7 In-block Flat Place Detection Means 8 In-block Filters Applicable flag holding means 9, 59, 79, 99, 119, 139, 169 Flat portion pattern holding means 10, 140, 170 In-block pixel filter means 11 Boundary pixel holding means 141, 171 Boundary peripheral pixel holding means 12, 42, 62 , 82, 102, 122, 142, 1
72 boundary pixel determination means 13, 143 boundary pixel processing means 14 image output means 20, 151 right boundary pixel selection means 21, 153 left boundary pixel selection means 150 right boundary pixel filter means 152 left boundary pixel filter means

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5B057 CC02 CE05 CE06 CG01 CH09                       CH11 DC16                 5C059 KK04 PP22 PP23 PP25 TA68                       TB08 TC02 TD05 TD12                 5C077 LL02 MP01 PP02 PP47 PP61                       PQ22 RR21                 5C078 AA04 BA42 CA21 DA01

Claims (13)

[Claims] 1. An input image memory for holding an original image, an inter-pixel difference code calculating means for calculating a code of a pixel difference of original image data obtained from the input image memory, and a process obtained from the input image memory. In-block filter application determination means for determining whether or not the in-block filter processing can be applied to the processing target block by detecting edge locations and flat locations in the image data in the target block, and processing obtained from the input image memory In-block flat portion detection means for detecting a flat portion of image data in the target block, and in-block flat portion if the in-block filter application determination means determines that the in-block filter is applied to the processing target block In the block to be processed, based on the flat location information in the block detected by the location detection means In-block pixel filter means for performing filter processing on flat portions of image data, inter-pixel difference code obtained by the inter-pixel difference code calculation means, and block obtained by the intra-block filter application determination means In-block filter information holding means for holding the in-block filter processing applicability determination result and in-block flat location information obtained by the in-block flat location detection means, and processing obtained by the in-block pixel filtering means A post-processing block image data holding means for holding the subsequent block image data, an inter-pixel difference code of the processing target block obtained by the inter-pixel difference code calculating means, and a processing target block obtained by the intra-block filter application determining means By the determination result of whether or not the in-block filter processing is applicable and the flat portion detection means in the block Resulting determination result of whether the intra-block flat portion information of the obtained block to be processed and the intra-block filter information held by the intra-block filter information holding unit is the inter-pixel difference code regarding the adjacent block and the intra-block filtering process regarding the adjacent block When,
Boundary pixel determination means for inspecting the state of the block boundary pixels of the processing target block and the adjacent block based on the in-block flat portion information on the adjacent block, and determining the processing for the block boundary pixel, and obtained by the boundary pixel determination means. Boundary pixel processing means for processing block boundary pixels based on the boundary pixel determination result, image output means for outputting image data from the in-block pixel filter means, the boundary pixel processing means and the input image memory as a video signal. An image processing apparatus comprising: 2. The image processing device according to claim 1, wherein the inter-pixel difference code calculation means includes: an inter-pixel difference code near a block boundary of a block to be processed; and an inter-pixel difference code near a block boundary of an adjacent block. And an inter-boundary pixel difference code of block boundary pixels of the processing target block and the adjacent block. 3. The image processing apparatus according to claim 1, wherein the boundary pixel determination unit determines whether or not the intra-block filter processing applicable to both or one of the processing target block and the adjacent block is valid. , Refer to the in-block flat portion information of a block for which the determination result of whether or not to apply the in-block filter processing is valid, and if a block boundary pixel is included in the in-block flat portion, pixels near the block boundary of the block Pixel value that makes the inter-pixel difference of the block boundary larger after the intra-block filter processing than the original image from the inter-difference code and the inter-boundary pixel difference code between the block boundary pixel of the block adjacent to the block Is checked in advance, and the boundary processing is performed on the block boundary pixels based on the inspection result. The image processing apparatus characterized by determining the implementation. 4. The image processing apparatus according to claim 1, wherein the boundary pixel determining unit determines whether or not the in-block filter processing applicable to both or one of the processing target block and the adjacent block is valid. , Refer to the in-block flat portion information of a block for which the determination result of whether or not to apply the in-block filter processing is valid, and if a block boundary pixel is included in the in-block flat portion, pixels near the block boundary of the block Pixel value that makes the inter-pixel difference of the block boundary larger after the intra-block filter processing than the original image from the inter-difference code and the inter-boundary pixel difference code between the block boundary pixel of the block adjacent to the block The number of pixels that can be taken is counted, and if the number of pixels exceeds a predetermined number, The image processing apparatus characterized by determining the implementation of boundary processing. 5. The image processing apparatus according to claim 1, wherein the boundary pixel determining unit determines whether or not the intra-block filtering process is applicable to both or one of the target block and the adjacent block is valid. , Refer to the in-block flat portion information of the block for which the in-block filter processing applicability determination result is valid, and if the in-block flat portion includes a block boundary pixel, and the peripheral pixels of the block boundary pixel are If a predetermined number or more are continuously flat, the block after the intra-block filter processing is performed from the inter-pixel difference code near the block boundary of the block and the inter-boundary pixel difference code with the block boundary pixel of the block adjacent to the block Can the pixel value of the boundary pixel be such that the difference between pixels at the block boundary is larger than that of the original image? The image processing apparatus characterized by emergence pre inspected to determine the implementation of the boundary processing for the block boundary pixel on the basis of the test results. 6. The image processing apparatus according to claim 1, wherein the boundary pixel determination unit determines whether or not the intra-block filtering process is applicable to both or one of the target block and the adjacent block is valid. , Refer to the in-block flat portion information of the block for which the in-block filter processing applicability determination result is valid, and if the in-block flat portion includes a block boundary pixel, and the peripheral pixels of the block boundary pixel are If a predetermined number or more are continuously flat, the block after the intra-block filter processing is performed from the inter-pixel difference code near the block boundary of the block and the inter-boundary pixel difference code with the block boundary pixel of the block adjacent to the block An image in which boundary pixels can take pixel values that make the difference between pixels at the block boundary larger than in the original image. Counted, the image processing apparatus characterized by the number of pixels to determine the implementation of the boundary processing for the block boundary pixels to exceed the predetermined number. 7. The image processing apparatus according to claim 1, wherein the boundary pixel processing unit outputs a boundary pixel of the original image instead of the intra-block filter processing pixel for the boundary processing execution pixel. Processing equipment. 8. An input image memory for holding an original image, an inter-pixel difference code calculating means for calculating a code of an inter-pixel difference of original image data obtained from the input image memory, and an original image obtained from the input image memory. An inter-pixel difference value calculating means for calculating an inter-pixel difference value between a block boundary pixel pixel of a block to be processed of image data and a block boundary pixel of an adjacent block, and an edge in image data in the block to be processed obtained from the input image memory In-block filter application determining means for determining whether or not in-block filter processing can be applied to the processing target block by detecting a flat portion and a flat portion, and detecting a flat portion in the processing target block obtained from the input image memory Block in the block to be processed, and the block application determination means in the block to be processed block When it is determined that the in-block filter is applied to the inside of the block that performs the filtering process on the flat portion of the block to be processed, based on the inside flat portion information detected by the inside flat portion detecting unit. Pixel filter means, inter-pixel difference code obtained by the inter-pixel difference code calculation means, in-block filter processing applicability determination result obtained by the in-block filter application decision means, and in-block flat portion detection In-block filter information holding means for holding the in-block flat portion information obtained by the means, and processed block image data holding means for holding the processed block image data obtained by the in-block pixel filter means And the inter-pixel difference code of the block to be processed obtained by the inter-pixel difference code calculating means and the block. Check result of the intra-block filter application of the processing target block obtained by the intra-block filter application decision means The block adjacent to the processing target block based on the inter-pixel difference code regarding the adjacent block, the determination result of whether the intra-block filtering process regarding the adjacent block is applicable, and the intra-block flat portion information regarding the adjacent block among the block filter information held by the means Boundary pixel determination means for inspecting the state of the block boundary pixels of the block and determining processing for the block boundary pixels, and boundary pixel processing for processing the block boundary pixels based on the boundary pixel determination result obtained by the boundary pixel determination means. Means and the internal image of the block The image processing apparatus characterized by comprising an image output means for outputting as a video signal image data filter means and said boundary pixel processing unit from the input image memory. 9. The image processing device according to claim 8, wherein the inter-pixel difference code calculation means includes: an inter-pixel difference code near a block boundary of a processing target block; and an inter-pixel difference code near a block boundary of an adjacent block. And an inter-boundary pixel difference code of block boundary pixels of the processing target block and the adjacent block. 10. The image processing device according to claim 8, wherein the boundary pixel determination unit determines whether or not the in-block filter processing application determination result of both or one of the processing target block and the adjacent block is valid. , Refer to the in-block flat portion information of the block for which the in-block filter processing applicability determination result is valid, and if the in-block flat portion includes a block boundary pixel, and includes the block boundary pixel, If the pixel difference value between the block boundary pixel of the processing target block and the block boundary pixel of the adjacent block is equal to or more than the first threshold value and equal to or less than the second threshold value, Inter-pixel difference code near the block boundary of the block and the boundary pixel between the block boundary pixel of the block adjacent to the block It is preliminarily inspected from the minute code whether or not the block boundary pixel after the intra-block filtering process can take a pixel value that makes the inter-pixel difference of the block boundary larger than the original image, and the block boundary pixel is determined based on the inspection result. An image processing apparatus, which determines execution of boundary processing. 11. The image processing apparatus according to claim 8, wherein the boundary pixel determining unit determines whether or not the intra-block filter processing applicable to both or one of the processing target block and the adjacent block is valid. , Refer to the in-block flat portion information of the block for which the in-block filter processing applicability determination result is valid, and if the in-block flat portion includes a block boundary pixel, and the peripheral pixels of the block boundary pixel are When the pixel difference value between the block boundary pixel of the processing target block and the block boundary pixel of the adjacent block is equal to or more than the first threshold value and equal to or less than the second threshold value, the number of pixels is continuously flat for a predetermined number or more. , The pixel difference code near the block boundary of the block and the boundary with the block boundary pixel of the block adjacent to the block Count the number of pixels that can take a pixel value that makes the block boundary pixel after the intra-block filter processing larger the pixel difference of the block boundary from the original difference code from the prime difference code, and the number of pixels exceeds a predetermined number In this case, the image processing apparatus is characterized by deciding whether to execute boundary processing for block boundary pixels. 12. The image processing apparatus according to claim 8, wherein the boundary pixel processing unit outputs a boundary pixel of the original image instead of the intra-block filter processing pixel for the boundary processing execution pixel. Processing equipment. 13. The image processing device according to claim 8, wherein the boundary pixel processing means performs smoothing on the boundary processed pixels after the intra-block filter processing and the adjacent pixels. A characteristic image processing device.