ADAPTIVE FILTERING METHOD AND APPARATUS

• US 20130182762A1
• Filed: 09/28/2011
• Published: 07/18/2013
• Est. Priority Date: 09/28/2010
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Seregin, Vadim, Chen, Jianle
• Granted Patent: US 9,344,716 B2
• Time in Patent Office: Days
• US Class Current: 375/240.03
• 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 19/14 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 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness

Abstract

A filtering method and apparatus for adaptively performing deblocking filtering are provided. The method includes: obtaining a parameter indicating how close pixel values of pixels adjacent to a block boundary are with respect to a predetermined line; determining a filtering strength at the block boundary based on the parameter; and performing filtering based on the filtering strength.

Claims

1. An adaptive filtering method comprising:

obtaining a parameter indicating a closeness of pixel values of pixels adjacent to a block boundary with respect to a predetermined line;

determining a filtering strength at the block boundary based on the obtained parameter; and

performing filtering based on the determined filtering strength.

2. The adaptive filtering method of claim 1, wherein the predetermined line is a polynomial based on the pixel values, a random curve, a function, or a straight line.

3. The adaptive filtering method of claim 1, wherein the obtaining the parameter comprises obtaining the parameter based on a difference between pixel values of pixels that are symmetrically positioned with respect to the block boundary.

4. The adaptive filtering method of claim 1, wherein the obtaining the parameter comprises obtaining the parameter based on a difference between pixel values of pixels that are symmetrically positioned with respect to the block boundary, and a difference between slopes that are determined according to distances between the pixels that are symmetrically positioned with respect to the block boundary.

5. The adaptive filtering method of claim 1, wherein, when pixel values of pixels positioned in a first side with respect to the block boundary are p0 and p1, pixel values of pixels positioned in a second side with respect to the block boundary are q0 and q1, the pixels having the pixel values of p0 and q0 are adjacent to the block boundary, and the parameter is a parameter Δ

, the obtaining the parameter comprises obtaining the parameter Δ

according to Equation Δ

=(9*(q0−

p0)−

3*(q1−

p1))/16.

6. The adaptive filtering method of claim 1, wherein the determining the filtering strength comprises determining the filtering strength based on a comparison between an absolute value of the parameter and a predetermined threshold value.

7. The adaptive filtering method of claim 6, wherein the predetermined threshold value is based on a quantization parameter (QP) used in quantization of blocks adjacent to the block boundary.

8. The adaptive filtering method of claim 6, wherein, if the absolute value of the parameter is greater than the predetermined threshold value, the filtering is not performed.

9. The adaptive filtering method of claim 1, wherein, when pixel values of pixels positioned in a first side with respect to the block boundary are p0, p1, and p2, pixel values of pixels positioned in a second side with respect to the block boundary are q0, q1, and q2, the pixels having the pixel values of p0 and q0 are adjacent to the block boundary, and the parameter is a parameter Δ

, if the parameter Δ

obtained according to Equation Δ

=(9*(q0−

p0)−

3*(q1−

p1))/16 is less than a predetermined threshold value, the performing the filtering comprises performing filtering according to an algorithm so as to replace the pixel values p0, p1, q0, and q1 with p0′

, p1′

, q0′

, and q1′

, the algorithm being;

18. A computer readable recording medium having recorded thereon a program executable by a computer for performing the method of claim 1.

10. An adaptive filtering apparatus comprising:

a parameter obtainer which obtains a parameter indicating a closeness of pixel values of pixels adjacent to a block boundary with respect to a predetermined line;

a filtering strength determiner which determines a filtering strength at the block boundary based on the obtained parameter; and

a filtering performer which performs filtering based on the determined filtering strength.

11. The adaptive filtering apparatus of claim 10, wherein the predetermined line is a polynomial based on the pixel values, a random curve, a function, or a straight line.

12. The adaptive filtering apparatus of claim 10, wherein the parameter obtaining unit obtains the parameter based on a difference between pixel values of pixels that are symmetrically positioned with respect to the block boundary.

13. The adaptive filtering apparatus of claim 10, wherein the parameter obtaining unit obtains the parameter based on a difference between pixel values of pixels that are symmetrically positioned with respect to the block boundary, and a difference between slopes that are determined according to distances between the pixels that are symmetrically positioned with respect to the block boundary.

14. The adaptive filtering apparatus of claim 10, wherein, when pixel values of pixels positioned in a first side with respect to the block boundary are p0 and p1, pixel values of pixels positioned in a second side with respect to the block boundary are q0 and q1, the pixels having the pixel values of p0 and q0 are adjacent to the block boundary, and the parameter is a parameter Δ

, the parameter obtaining unit obtains the parameter Δ

according to Equation Δ

=(9*(q0−

p0)−

3*(q1−

p1))/16.

15. The adaptive filtering apparatus of claim 10, wherein, when pixel values of pixels positioned in a first side with respect to the block boundary are p0, p1, and p2, pixel values of pixels positioned in a second side with respect to the block boundary are q0, q1, and q2, the pixels having the pixel values of p0 and q0 are adjacent to the block boundary, and the parameter is a parameter Δ

, if the parameter Δ

obtained according to Equation Δ

=(9*(q0−

p0)−

3*(q1−

p1))/16 is less than a predetermined threshold value, the filtering performing unit performs filtering according to an algorithm so as to replace the pixel values p0, p1, q0, and q1 with p0′

, p1′

, q0′

, and q1′

, the algorithm being;

16. An adaptive filtering method comprising:

determining a filtering strength at a block boundary based on a closeness of pixel values of pixels adjacent to the block boundary with respect to a predetermined line; and

performing filtering based on the determined filtering strength.

17. The adaptive filtering method of claim 16, wherein the determining the filtering strength comprises determining the filtering strength based on a comparison between an absolute value of the parameter and a predetermined threshold value.

19. A computer readable recording medium having recorded thereon a program executable by a computer for performing the method of claim 16.