KR20200089545A - Method for compressing binary image based 2x2 block - Google Patents

Abstract

Disclosed is a method for compressing a binary image based on a 2x2 block. According to an embodiment of the present invention, the method for compressing a binary image based on a 2x2 block comprises the steps of: determining whether pixels included in a random block belong to existing patterns; calculating the number N (N is a natural number, hereinafter the same) of pixels belonging to the existing patterns; and compressing, when the N is equal to or greater than a predetermined value, the data of the block into a binary bit stream including pixel pattern type information with respect to pixels belonging to the existing patterns and color information with respect to pixels having a new pattern. According to the present invention, the method for compressing a binary image based on a 2x2 block has an advantage of reducing the loss of information which may occur in a process of compressing and reconstructing a binary pattern, thereby visually reducing a difference in the quality between an original image and a reconstructed image.

Description

Method for compressing binary image based on 2×2 blocks{Method for compressing binary image based 2x2 block}

The present invention relates to image compression. In particular, when pixels having a repetitive pattern and pixels having an irregular pattern exist in one block, in performing 2x2 block-based binary image compression, for pixels belonging to an existing pattern The present invention relates to a 2x2 block-based binary image compression method capable of preventing deterioration of visual quality efficiently and by compressing with minimal information and adding color information for pixels having irregular patterns to a bit stream.

The 2x2 block-based binary image compression algorithm according to the prior art compresses image data using a difference in values between adjacent pixels. This method is also called a DPCM (Differential Pulse Code Modulation) method.

However, according to the DPCM, when a pixel belonging to an existing pattern and a new pixel exist in one block, loss of information in a process of compressing and restoring an image for all pixels existing in the corresponding block may occur significantly. This also affects blocks that are subsequently compressed. Therefore, according to the binary image compression method according to the related art, when a block having many irregular patterns and a block adjacent to the block are compared with the original, there is a problem that serious visual image quality deterioration occurs.

The technical problem to be achieved by the present invention is to provide a 2x2 block-based binary image compression method capable of performing efficient compression while minimizing deterioration of visual image quality.

The binary image compression method according to an embodiment of the present invention for achieving the above technical problem includes determining whether pixels included in an arbitrary block belong to existing patterns, and the number N of pixels belonging to the existing patterns N(N is Calculating a natural number, hereinafter the same), and when the N is greater than or equal to a predetermined value, includes data of the block, pixel pattern type information for pixels belonging to the existing patterns, and color information for pixels having a new pattern. And compressing it into a binary bit stream.

Preferably, the binary bit stream may further include mode information indicating whether the binary bit stream includes compressed binary image information. Alternatively, the binary bit stream may further include sub-mode information indicating whether to use the existing pattern. In addition, when the pixels included in the block are sequentially referred to as first to M (M is a natural number greater than or equal to N, hereinafter equal), the binary bit stream is whether or not the first to Nth pixels belong to the existing pattern. It may further include pattern information indicating. In addition, the binary bit stream may further include information on the N.

Preferably, when an arbitrary pixel belongs to the existing pattern, a step of determining which of the existing patterns the pixel belongs to may be further provided. In this case, the pixel pattern type information may include information on which pattern the pixels belonging to the existing patterns belong to.

Preferably, the color information may be an RGB value of a corresponding pixel. Preferably, when the block includes two or more pixels having a new pattern, the color information may be an average value of pixels having the new pattern.

Preferably, when N is smaller than a predetermined value, a step of compressing data of the block by a differential pulse code conversion method may be further provided.

Preferably, the binary image compression method may be an image compression method based on a 2x2 block. At this time, the predetermined value may be 2.

The 2x2 block-based binary image compression method according to the present invention has an advantage of visually improving a difference in image quality between an original image and a reconstructed image by reducing loss of information that may occur during compression and restoration of a binary pattern.

Therefore, the 2x2 block-based binary image compression method according to the present invention can be applied to a video compression circuit that emphasizes image quality, such as a frame memory compression engine of a response speed compensation circuit of an LCD panel or a compression circuit for image transmission that occupies a wide bandwidth. There will be.

BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand the drawings cited in the detailed description of the present invention, a brief description of each drawing is provided.
1 is a flowchart illustrating a binary image compression method according to the present invention.
FIG. 2 is a diagram illustrating image data compressed by the binary image compression method of FIG. 1.
FIG. 3 is a diagram illustrating the structure of a binary bit stream according to the binary image compression method of FIG. 1 when N is "3".
FIG. 4 is a diagram illustrating the structure of a binary bit stream according to the binary image compression method of FIG. 1 when N is "2".

In order to fully understand the present invention and the operational advantages of the present invention and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the contents described in the drawings, which illustrate preferred embodiments of the invention.

Hereinafter, the present invention will be described in detail by explaining preferred embodiments of the present invention with reference to the accompanying drawings. The same reference numerals in each drawing denote the same members.

1 is a flowchart illustrating a binary image compression method according to an embodiment of the present invention. The binary image compression method according to the present invention may be a 2x2 block-based binary image compression method for compressing a block by configuring image data into 2x2 blocks, as shown in FIG. 2.

Hereinafter, it is assumed that the block described for the binary image compression method according to the present invention includes four pixels, as shown in FIG. 2. Also, it is assumed that the four pixels included in each block are the first pixel P1, the second pixel P2, the third pixel P3, and the fourth pixel P4, as shown in FIG. 2. . Although FIG. 2 designates only pixels for the x (x is a natural number, hereinafter the same) block BLKx, the pixels such as the i (i is a natural number, hereinafter the same) block BLKi are also the first. It is referred to as a pixel P1, a second pixel P2, a third pixel P3, and a fourth pixel P4.

In addition, it is assumed that each pixel has a defined existing A pattern or B pattern, or a new pattern. The A pattern or the B pattern refers to an existing pattern defined in a binary image compression method based on a 2x2 block, and relates to a matter that can be easily performed by those skilled in the art to which the present invention pertains.

1 and 2, the binary image compression method 100 according to an embodiment of the present invention first receives pixels included in an arbitrary block (S110 ). Next, it is determined whether the received pixel belongs to the existing patterns (S120).

When the received pixel belongs to the existing patterns (YES in S120), information on which of the existing patterns belongs is stored (S130). That is, information on whether the received pixel belongs to the A pattern or the B pattern is stored (S130). On the other hand, if the received pixel does not belong to the existing patterns ("No" in S120), information on the received pixel is stored (S140). In this case, information on the received pixel may be color information of a pixel, that is, an RGB value. In this case, the above information may be a memory (not shown) included in a system for compressing image data according to the present invention.

The above operation is performed on all pixels included in the corresponding block (S150, S160). When the determination of all the pixels included in one block is finished (YES in S150), the binary image compression method 100 according to an embodiment of the present invention is applied to an existing pattern (A pattern or B pattern) in the corresponding block. The number N of pixels (N is a natural number, hereinafter the same) is calculated (S170).

Look at the example of FIG. 2. All pixels P1 to P4 of the x-th block BLKx belong to an existing pattern. That is, it can be seen that the first pixel P1 and the fourth pixel P4 belong to the A pattern, and the second pixel P2 and the third pixel P3 belong to the B pattern. Therefore, the N value for the xth block BLKx is "4".

In the case of the i-th block BLKi, it can be seen that the first pixel P1 belongs to the A pattern, and the second pixel P2 and the third pixel P3 belong to the B pattern. On the other hand, the fourth pixel P4 has a new pattern, not an existing pattern. Therefore, the N value for the i-th block BLKi is "3".

In addition, in the case of the j-th block BLKj, it can be seen that the first pixel P1 belongs to the A pattern, and the third pixel P3 belongs to the B pattern. On the other hand, the second pixel P2 and the fourth pixel P4 have a new pattern, not an existing pattern. Therefore, the N value for the j-th block BLKj is "2". In addition, the second pixel P2 and the fourth pixel P4 of the j-th block BLKj may have different patterns.

Next, the present invention 100 determines whether the value of N is greater than or equal to a predetermined value (S180). In particular, the binary image compression method 100 according to an embodiment of the present invention may set a predetermined value to "2". The predetermined value may be set to a value other than "2" depending on the performance of the system.

However, when there are three or more pixels having a new pattern in one block (N = "0", "1"), it may be efficient by a binary image compression method according to conventional technology such as DPCM ( S300).

1 and 2, when N is "2" or more, the binary image compression method 100 according to an embodiment of the present invention compresses a block into a binary bit stream having a data structure described below (S190). ).

Hereinafter, the structure of the binary bit stream according to the present invention for the case where N is "2" and N is "3" will be described. As described above, when N is “2”, pixels having the same pattern as the j block BLKj of FIG. 2 may be included, and when N is “3”, the i block BLKi of FIG. 2 may be included. ).

First, when N is "3", that is, a binary bit stream for a block such as the i block BLKi in FIG. 2 will be described.

3 is a diagram illustrating an example of a binary bit stream BSTi for the i-th block BLKi.

2 and 3, the binary bit stream (BSTi) includes mode information (1), sub mode information (2), pattern information (3), information about N (4), and pixel pattern type information (5). And color information (6, 7, 8). However, the present invention is not limited thereto, and may include only some of the plurality of pieces of information or other information.

The content, size and value of each information will be described in more detail.

The mode information 1 may be provided with 4 bits, as shown in FIG. 3. The mode information 1 indicates that the binary bit stream (BST i) includes binary image information. Accordingly, the binary bit stream by the binary image compression method according to the present invention can be set to have a binary value such as "1111".

The sub mode information 2 may be provided with 1 bit. The sub-mode information 2 may indicate whether the binary bit stream BSTi uses an existing pattern (A pattern or B pattern). Therefore, the binary bit stream by the binary image compression method according to the present invention can be set to have a binary value such as "0".

The pattern information 3 may be provided in 3 bits. The pattern information 3 may indicate whether the first pixel P1 to the third pixel P3 of the corresponding block belong to an existing pattern. The present invention can be set to have a binary value "1" for pixels having an existing pattern and a binary value "0" for pixels having a new pattern. In the case of the i-block BLKi, since the first pixel P1 to the third pixel P3 of the i-block BLKi belong to an existing pattern, a binary value such as “111” may be obtained as shown in FIG. 3. However, even if N is "3", in the case of a block in which the first pixel P1, the third pixel P3, and the fourth pixel P4 have an existing pattern, unlike the i-th block BLKi, pattern information (3) may have a binary value of "101". That is, since the binary bit stream BSTi of FIG. 3 is a binary bit stream when only one pixel having a new pattern exists in one block, through the pattern information 3, the first pixel P1 to the third pixel In addition to (P3), it may be inferred whether the fourth pixel P4 belongs to an existing pattern.

Whether the binary bit stream BSTi of FIG. 3 is a binary bit stream corresponding to the case where N is "3" can be known through information 4 about N. The information 4 for N may be provided in 1 bit or more, and in the case of the binary bit stream BSTi of FIG. 3, 2 bits. When N is "3", information 4 for N may have a binary value such as "11".

Next, the binary bit stream BSTi of FIG. 3 may include pixel pattern type information 5 having 3 bits. The pixel pattern type information 5 may indicate which of the A pattern and the B pattern belongs to pixels belonging to the existing pattern. The present invention can be set to have the binary value "0" when the pixel belongs to the A pattern, and the binary value "1" when the pixel belongs to the B pattern. Thus, the binary of FIG. 3 for the i block BLKi of FIG. 2

The bitstream BSTi may have a binary value such as "011".

The color information 6, 7, 8 may be provided by 8 bits for R, G, and B values for a pixel (fourth pixel P4) having a new pattern, respectively. However, R, G, and B values may be stored in the upper 7 bits of the 8 bits. In addition, the stored R, G, and B values may be stored only in some upper bits according to the compression rate.

By generating the binary bit stream as described above, compression for one block BLKi can be performed. Next, when N is "2", that is, a compression method for a block such as the j block BLKj of FIG. 2 will be described.

4 is a diagram illustrating an example of a binary bit stream BSTj for the j-th block BLKj.

2 and 4, the binary bit stream (BSTj) also, like the binary bit stream of FIG. 3, mode information (1), sub mode information (2), pattern information (3), pixel pattern type information (4), information (5) for N and color information (6, 7, 8). In addition, the content indicated by each information is the same. However, the size and value of some information may be different from the binary bit stream (BSTi) of FIG. 3. Explain in more detail.

The mode information 1 and sub-mode information 2 of the binary bit stream BSTj of FIG. 4 are the same as those of FIG. 3. Also, the binary bit stream BSTj of FIG. 4 may include 3 bits of pattern information 3 as in FIG. 3. However, in the j block BLK j, since the first pixel P1 and the third pixel P3 belong to an existing pattern, and the second pixel P2 belongs to a new pattern, the pattern information 3 is a binary value "101".

On the other hand, since the binary bit stream BSTj of FIG. 4 is a binary bit stream for a block in which N is "2", information about N may have a binary value "10". Similarly, the pixel pattern type information 5 may be provided with 2 bits because only the first pixel P1 and the third pixel P3 of the j-th block BLKj belong to the existing pattern, unlike FIG. 3. At this time, since the first pixel P1 of the j-th block BLKj belongs to the A pattern and the third pixel P3 belongs to the B pattern, the pixel pattern type information 4 of FIG. 4 is a binary value such as “01”. Can have

The color information (6, 7, 8) of the binary bit stream (BSTj) of FIG. 4 is R, G, and B values for a pixel (fourth pixel (P4)) having a new pattern, respectively, as shown in FIG. It may be provided for each 8 bits. In addition, R, G, and B values may be stored in the upper 7 bits of the 8 bits. However, the color information 6, 7, 8 of the binary bit stream BSTj of FIG. 4 is an average value of color information of two pixels having a new pattern, that is, the second pixel P2 and the fourth pixel P4. Each of RGB may have an average value.

As described above, in the binary image compression method according to the present invention, in the case of 2x2 block-based binary image compression, when an existing pattern and a new pattern are mixed in one block, the pixels belonging to the existing pattern are compressed with minimal information, By including color information for a pixel of a new pattern, it is possible to prevent degradation of image quality while being efficient. As described above, optimal embodiments have been disclosed in the drawings and specifications. Although specific terms are used herein, they are used only for the purpose of describing the present invention, and are not used to limit the scope of the present invention as defined in the claims or the claims. Therefore, those skilled in the art will understand that various modifications and other equivalent embodiments are possible therefrom.

For example, the case where there are 4 pixels belonging to the existing patterns is not described, but from the description of the i block of FIG. 2 with 3 pixels belonging to the existing patterns, a person skilled in the art to which the present invention pertains Will be easy to implement.

Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

Claims (21)

Determining whether pixels included in an arbitrary block belong to existing patterns;
Calculating the number N of pixels belonging to the existing patterns (N is a natural number, hereinafter the same); And
When N is greater than or equal to a predetermined value,
And compressing the block into a binary bit stream including information on a pattern of pixels belonging to the existing patterns and color information on a pixel having a new pattern. The method of claim 1, wherein the binary bit stream,
And further comprising mode information indicating whether the binary bit stream includes compressed binary image information. The method of claim 1, wherein the binary bit stream,
Binary image compression method, characterized in that it further comprises sub-mode information indicating whether to use the existing pattern. According to claim 1,
When the pixels included in the block are sequentially referred to as first to M (M is a natural number greater than or equal to N, hereinafter equal) pixels,
The binary bit stream,
A binary image compression method, further comprising pattern information indicating whether the first to Nth pixels belong to the existing pattern. The method of claim 1, wherein the binary bit stream,
Binary image compression method, characterized in that it further comprises information about the N. The method of claim 1, wherein the binary bit stream,
A binary image compression method, characterized in that it further comprises pixel pattern type information on which of the N patterns belonging to the existing pattern belongs to the existing pattern. According to claim 1,
If any pixel belongs to the existing pattern,
And determining which of the existing patterns the pixel belongs to. The method of claim 7, wherein the binary bit stream,
Binary image compression method, characterized in that it comprises pixel pattern type information about which pattern belongs to the pixels belonging to the existing patterns. The method of claim 1, wherein the color information,
Binary image compression method, characterized in that the R, G, B values of the corresponding pixel. The method of claim 1, wherein the color information,
A binary image compression method characterized by storing only the upper part of the bits of the R, G, and B values of the corresponding pixel according to the compression rate. According to claim 1,
When the block includes two or more pixels having a new pattern,
The color information,
Binary image compression method, characterized in that the average value of the pixels having the new pattern. The method of claim 1, wherein the binary bit stream,
Mode information indicating whether the binary bit stream includes compressed binary image information;
Sub-mode information indicating whether to use the existing pattern;
Pattern information indicating whether the first to Nth pixels belong to the existing pattern when the pixels included in the block are sequentially referred to as first to Mth pixels;
Information about the N;
Pixel pattern type information on which of the existing patterns belong to the N patterns belonging to the existing pattern; And
Binary image compression method comprising the color information for the pixels having the new pattern. According to claim 1,
When N is smaller than a predetermined value,
And compressing the data of the block by a differential pulse code conversion (DCPM) method. The method of claim 1, wherein the binary image compression method,
Binary image compression method, characterized in that the image compression method based on a 2x2 block. The method of claim 1, wherein the predetermined value,
Binary image compression method, characterized in that 2. In the 2x2 block-based binary image compression method,
Determining whether pixels included in an arbitrary block belong to a defined A pattern or B pattern;
Calculating the number N of pixels belonging to the A pattern or the B pattern; And
When N is greater than or equal to a predetermined value,
The block, a pixel having the new pattern and information about the pattern of the pixels belonging to the A pattern or the B pattern
And compressing into a binary bit stream containing color information for 2x2 block-based binary image compression. The method of claim 16,
The binary bit stream,
Mode information indicating whether the binary bit stream includes compressed binary image information;
Sub-mode information indicating whether to use the A pattern or the B pattern;
Pattern information indicating whether the first three pixels included in the block belong to the A pattern or the B pattern; Information about the N;
Pixels of which of the A patterns and the B patterns belong to the N pixels belonging to the existing pattern
Pattern type information; And color information on pixels having the new pattern. The method of claim 16, wherein the predetermined value,
Binary image compression method, characterized in that 2. The method of claim 16,
When N is 3,
The color information,
2x2 block-based binary image compression method, characterized in that the RGB value of the corresponding pixel. The method of claim 16,
When N is 2,
The color information,
2x2 block-based binary image compression method, characterized in that the average value of the two pixels with the new pattern. The method of claim 16,
When N is less than 2,
2x2 block-based binary image compression method characterized in that it further comprises the step of compressing the data of the block by a differential pulse code conversion (DCPM (Differential Pulse Code Modulation)) method.

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