DEBLOCK METHOD AND IMAGE PROCESSING APPARATUS

• US 20100177983A1
• Filed: 03/12/2009
• Published: 07/15/2010
• Est. Priority Date: 01/15/2009
• Status: Active Grant

• Current Assignee: Silicon Integrated Systems Corporation (Silicon Integrated Systems Corporation Taiwan)
• Original Assignee: Silicon Integrated Systems Corporation (Silicon Integrated Systems Corporation Taiwan)
• Inventors: Hsu, Jeng-Yun
• Granted Patent: US 8,422,800 B2
• Time in Patent Office: Days
• US Class Current: 382/268
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/137 Motion inside a coding unit, e.g. average field, frame or block difference
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/182 the unit being a pixel
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/80 Details of filtering operations specially adapted for video compression, e.g. for pixel interpolation H04N19/635, H04N19/86 take precedence
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness

Abstract

A deblock method for processing at least one image including a plurality of pixels. The method comprises the step of determining a shift amount of block boundary by pixel data differences between adjacent pixels and thereby determining block boundaries between macroblocks in the image, and the step of optionally performing a deblock process on the block boundaries.

Claims

1. A deblock method, for processing at least one image comprising a plurality of pixels, the method comprising:

determining a shift amount of block boundary of the image by utilizing pixel data differences between adjacent pixels in the image in a first direction to thereby determine block boundaries of a second direction between adjacent macroblocks in the image; and

optionally performing a deblock process in the first direction on the block boundaries of the second direction;

wherein the first direction is either a horizontal or vertical direction and the second direction is perpendicular to the first direction.

2. The method according to claim 1, further comprising:

determining whether the shift amount of block boundary is reliable or not to thereby decide the value of a filter selection signal.

3. The method according to claim 2, wherein the step of optionally performing a deblock process on the block boundaries comprises optionally performing a deblock process in the first direction on the block boundaries of the second direction according to the filter selection signal.

4. The method according to claim 3, wherein at least one image is a plurality of images to form a video.

5. The method according to claim 4, wherein the step of determining the block boundaries of the second direction between adjacent macroblocks in the image comprises:

(a) using the pixel data differences to acquire the pixel boundary characteristic value of these pixels where the pixel boundary characteristic value of these pixels is set to a first value if the pixel data differences contain the characteristic of the block boundary of the macroblocks;

(b) categorizing these pixels into a plurality of groups in the first direction; and

(c) determining the shift amount of the block boundaries according to the pixel boundary characteristic value of these pixels having the first value as their pixel boundary characteristic value in the groups.

6. The method according to claim 5, wherein the step (c) comprises counting the number of the pixels having the first value as their pixel boundary characteristic value in each group and setting the group having the maximum count as the shift amount of block boundary.

7. The method according to claim 5, wherein the step (a) comprises using a weighting relation to increase the weight of the pixel boundary characteristic value of the pixels having the first value as their pixel boundary characteristic value and the step (c) comprises accumulating the weighted pixel boundary characteristic values of the pixels for each group separately to acquire a plurality of accumulated weights and thereby setting the group having the maximum accumulated weight among the accumulated weights as the shift amount of block boundary.

8. The method according to claim 7, wherein the step of determining whether the shift amount of block boundary is reliable or not comprises determining whether the shift amount of block boundary is reliable or not according to the maximum accumulated weight.

9. The method according to claim 8, wherein the step of determining whether the shift amount of block boundary is reliable or not further comprises calculating a degree of unreliability of the shift amount of block boundary if the shift amount of block boundary is unreliable and setting the value of the filter selection signal to a disable filter value if the degree of unreliability is beyond a threshold value of unreliability.

10. The method according to claim 9, wherein the step of determining whether the shift amount of block boundary is reliable or not further comprises:

(d) calculating a degree of reliability of the shift amount of block boundary if the shift amount of block boundary is reliable and setting the value of the filter selection signal to an enable filter value if the degree of reliability is beyond a threshold value of reliability.

11. The method according to claim 10, wherein the step (d) comprises the step of using the relation between the shift amount of block boundary of the image and a preceding shift amount of block boundary of a preceding image to calculate the degree of reliability of the shift amount of block boundary of the image.

12. The method according to claim 11, wherein the step (d) comprises increasing the degree of reliability while the shift amount of block boundary of the image is equal to the preceding shift amount of block boundary of the preceding image and decreasing the degree of reliability while the shift amount of block boundary of the image is different from the preceding shift amount of block boundary of the preceding image.

13. The method according to claim 1, wherein the step of optionally performing a deblock process in the first direction on the block boundaries of the second direction uses a low-pass filter to execute.

14. The method according to claim 13, wherein the low-pass filter uses at least one deblocking gain to acquire a plurality of adjusting coefficients and uses the adjusting coefficients and pixel data of a boundary pixel and a plurality of adjacent pixels to adjust the pixel data of the boundary pixel where the sum of the adjusting coefficients equals 1, the boundary pixel and the adjacent pixels form a row in the first direction and the boundary pixel is positioned at the center of the adjacent pixels.

15. The method according to claim 14, wherein the low-pass filter uses a first deblocking gain to adjust the pixel data of the boundary pixel when the pixel data difference of the boundary pixel is between a first boundary threshold value and a second boundary threshold value.

16. The method according to claim 15, wherein the adjacent pixels comprise a first pixel and a second pixel;

the boundary pixel is positioned between the first pixel and the second pixel; and

the low-pass filter uses the pixel data difference between the first pixel and the boundary pixel and the pixel data difference between the second pixel and the boundary pixel to acquire the first deblocking gain.

17. The method according to claim 15, wherein the low-pass filter further uses a second deblocking gain to adjust the pixel data of the adjacent pixels and the second deblocking gain is less than the first deblocking gain.

18. The method according to claim 13, wherein the low-pass filter further adjusts the filtering amplitude thereof according to the degree of motion of the image.

19. The method according to claim 14, wherein the low-pass filter further adjusts the deblocking gains according to the degree of motion of the image.

20. The method according to claim 1, wherein the pixel data differences are luminance differences or chrominance differences.

21. An image processing apparatus for processing at least one image comprising a plurality of pixels, the apparatus comprising:

a block boundary determining device, determining a shift amount of block boundary of the image by utilizing pixel data differences between adjacent pixels in the image in a first direction to thereby determine block boundaries of a second direction between adjacent macroblocks in the image; and

a deblock filter, optionally performing a deblock process in the first direction on the block boundaries of the second direction;

wherein the first direction is either a horizontal or vertical direction and the second direction is perpendicular to the first direction.

22. The apparatus according to claim 21, further comprising:

a filter control device, determining whether the shift amount of block boundary is reliable or not to thereby decide the value of a filter selection signal.

23. The apparatus according to claim 21, wherein the deblock filter optionally performs a deblock process in the first direction on the block boundaries of the second direction according to the filter selection signal.

24. The apparatus according to claim 21, wherein the deblock filter comprises a low-pass filter.

25. The apparatus according to claim 24, wherein the low-pass filter further adjusts the filtering amplitude thereof according to the degree of motion of the image.

26. The apparatus according to claim 24, wherein the low-pass filter uses at least one deblocking gain to acquire a plurality of adjusting coefficients and uses the adjusting coefficients and pixel data of a boundary pixel and a plurality of adjacent pixels to adjust the pixel data of the boundary pixel where the sum of the adjusting coefficients equals 1, the boundary pixel and the adjacent pixels form a row in the first direction and the boundary pixel is positioned at the center of the adjacent pixels.

27. The apparatus according to claim 26, wherein the low-pass filter uses a first deblocking gain to adjust the pixel data of the boundary pixel when the pixel data difference of the boundary pixel is between a first boundary threshold value and a second boundary threshold value.

28. The apparatus according to claim 27, wherein the adjacent pixels comprise a first pixel and a second pixel;

the boundary pixel is positioned between the first pixel and the second pixel; and

the low-pass filter uses the pixel data difference between the first pixel and the boundary pixel and the pixel data difference between the second pixel and the boundary pixel to acquire the first deblocking gain.

29. The apparatus according to claim 27, wherein the low-pass filter further uses a second deblocking gain to adjust the pixel data of the adjacent pixels and the second deblocking gain is less than the first deblocking gain.

30. The apparatus according to claim 26, wherein the low-pass filter further adjusts the deblocking gains according to the degree of motion of the image.

31. The apparatus according to claim 21, wherein the pixel data differences are luminance differences or chrominance differences.

32. The apparatus according to claim 21, wherein the block boundary determining device categorizes these pixels into a plurality of groups in the first direction;

acquires the pixel boundary characteristic value of these pixels according to the pixel data differences; and

determines the shift amount of the block boundary according to the pixel boundary characteristic value of these pixels having the first value as their pixel boundary characteristic value in the groups;

where the pixel boundary characteristic value of these pixels is set to a first value if the pixel data differences contain the characteristic of the block boundary of the macroblocks.

33. The apparatus according to claim 32, wherein the block boundary determining device counts the number of the pixels having the first value as their pixel boundary characteristic value in each group and sets the group having the maximum count as the shift amount of the block boundary.

34. The apparatus according to claim 32, wherein the block boundary determining device uses a weighting relation to increase the weight of the pixel boundary characteristic value of the pixels having the first value as their pixel boundary characteristic value and accumulates the weighted pixel boundary characteristic values of the pixels for each group separately to acquire a plurality of accumulated weights to thereby set the group having the maximum accumulated weight among the accumulated weights as the shift amount of the block boundary.