IMAGE PROCESSING DEVICE AND IMAGE PROCESSING METHOD

• US 20140112396A1
• Filed: 05/28/2012
• Published: 04/24/2014
• Est. Priority Date: 06/28/2011
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Ikeda, Masaru
• Granted Patent: US 10,291,937 B2
• Time in Patent Office: Days
• US Class Current: 375/240.29
• 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 19/124 Quantisation
• CPC Class Codes: H04N 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/182 the unit being a pixel
• CPC Class Codes: H04N 19/42 characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation H04N19/635 takes precedence
• 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 19/82 involving filtering within a prediction loop
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness

Abstract

The present technology relates to an image processing device and an image processing method which allow a deblocking filtering process to apply filtering appropriately. A pixel (p0_i) of which the value is 255 (solid line) before a deblocking process changes greatly to 159 (dot line) after a conventional deblocking process. Therefore, a clipping process having a clipping value of 10 is performed in strong filtering, whereby the pixel (p0_i) of which the value is 255 (solid line) before the deblocking process becomes 245 (bold line). Thus, a change in the pixel value occurring in the conventional technique can be suppressed as much as possible. This disclosure can be applied to an image processing device, for example.

Claims

1. An image processing device comprising:

a decoding unit that decodes an encoded stream encoded in units each having a layer structure to generate an image;

a filtering unit that applies a deblocking filter to a block boundary according to a strength of the deblocking filter applied to the block boundary which is a boundary between a block of the image generated by the decoding unit and an adjacent block adjacent to the block; and

a controller that controls the filtering unit so that, when strong filtering is applied as the strength of the deblocking filter, a clipping process is applied to the deblocking filter with respect to luminance components of the image generated by the decoding unit.

2. The image processing device according to claim 1, wherein

the controller applies the clipping process to values of parts that change when the deblocking filter is applied.

3. The image processing device according to claim 2, wherein

the controller applies the clipping process according to the following expressions:

p0_i=p0_i+Clip<sub>(−

pv)−

(pv)</sub>((p2_i+2*p1_i−

6*p0_i+2*q0_i+q1_i+4)>

>

3);

q0_i=q0_i+Clip<sub>(−

pv)−

(pv)</sub>((p1_i+2*p0_i−

6*p0_i+2*q1_i+q2_i+4)>

>

3);

p1_i=p1_i+Clip<sub>(−

pv)−

(pv)</sub>((p2_i−

3*p1_i+p0_i+q0_i+2)>

>

2);

q1_i=q1_i+Clip<sub>(−

pv)−

(pv)</sub>((p0_i+q0_i−

3*q1_i+q2_i+2)>

>

2);

p2_i=p2_i+Clip<sub>(−

pv)−

(pv)</sub>((2*p2_i−

5*p2_i+p1_i+p0_i+q0_i+4)>

>

3);

q2_i=q2_i+Clip<sub>(−

pv)−

(pv)</sub>((p0_i+q0_i+p1_i−

5*q2_i+2*q3_i+4)>

>

3);

 

 

[Mathematical formula 37]

where i=0, 7 and pv is a clipping value.

4. The image processing device according to claim 3, wherein

the controller sets a value that is integer multiples of parameters of the deblocking filter as the clipping value used when the clipping process is performed.

5. The image processing device according to claim 4, wherein

the controller sets a value that is twice the parameters of the deblocking filter as the clipping value used when the clipping process is performed.

6. The image processing device according to claim 1, further comprising:

a filter strength determining unit that determines the strength of the deblocking filter applied to the block boundary, wherein

the filtering unit applies the deblocking filter to the block boundary according to the strength determined by the filter strength determining unit, and

the controller controls the filtering unit so that, when the filter strength determining unit determines that strong filtering is to be applied, a clipping process is applied to the deblocking filter with respect to the luminance components of the image generated by the decoding unit.

7. The image processing device according to claim 6, wherein

the filter strength determining unit determines the strength of the deblocking filter using a plurality of lines as processing units.

8. The image processing device according to claim 7, wherein

the filter strength determining unit determines the strength of the deblocking filter using four lines as the processing units.

9. The image processing device according to claim 7, further comprising:

a filtering necessity determining unit that determines whether the deblocking filter is to be applied to the block boundary using a plurality of lines as processing units, wherein

the filter strength determining unit determines the strength of the deblocking filter when the filtering necessity determining unit determines that the deblocking filter is to be applied.

10. An image processing method for allowing an image processing device to execute:

decoding an encoded stream encoded in units each having a layer structure to generate an image;

applying a deblocking filter to a block boundary according to a strength of the deblocking filter applied to the block boundary which is a boundary between a block of the generated image and an adjacent block adjacent to the block; and

controlling so that, when strong filtering is applied as the strength of the deblocking filter, a clipping process is applied to the deblocking filter with respect to luminance components of the generated image.

11. An image processing device comprising:

a filtering unit that applies a deblocking filter to a block boundary according to a strength of the deblocking filter applied to the block boundary which is a boundary between a block of an image locally decoded when an image is encoded and an adjacent block adjacent to the block;

a controller that controls the filtering unit so that, when strong filtering is applied as the strength of the deblocking filter, a clipping process is applied to the deblocking filter with respect to luminance components of the locally decoded image; and

an encoding unit that encodes the image in units each having a layer structure using an image to which the deblocking filter is applied.

12. The image processing device according to claim 11, wherein

the controller applies the clipping process to values of parts that change when the deblocking filter is applied.

13. The image processing device according to claim 12, wherein

the controller applies the clipping process according to the following expressions:

p0_i=p0_i+Clip<sub>(−

pv)−

(pv)</sub>((p2_i+2*p1_i−

6*p0_i+2*q0_i+q1_i+4)>

>

3));

q0_i=q0_i+Clip<sub>(−

pv)−

(pv)</sub>((p1_i+2*p0_i−

6*q0_i+2*q1_i+q2_i+4)>

>

3));

p1_i=p1_i+Clip<sub>(−

pv)−

(pv)</sub>((p2_i−

3*p1_i+p0_i+q0_i+2)>

>

2));

q1_i=q1_i+Clip<sub>(−

pv)−

(pv)</sub>((p0_i+q0_i−

3*q1_i+q2i+2)>

>

2));

p2_i=p2_i+Clip<sub>(−

pv)−

(pv)</sub>((2*p2_i−

5*p2_i+p1_i+p0_i+q0_i+4)>

>

3));

q2_i=q2_i+Clip<sub>(−

pv)−

(pv)</sub>((p0_i+q0_i+p1_i−

5*q2_i+2*q3i+4)>

>

3));

 

 

[Mathematical formula 38]

where i=0, 7 and pv is a clipping value.

14. The image processing device according to claim 13, wherein

the controller sets a value that is integer multiples of parameters of the deblocking filter as the clipping value used when the clipping process is performed.

15. The image processing device according to claim 14, wherein

the controller sets a value that is twice the parameters of the deblocking filter as the clipping value used when the clipping process is performed.

16. The image processing device according to claim 11, further comprising:

a filter strength determining unit that determines the strength of the deblocking filter applied to the block boundary, wherein

the filtering unit applies the deblocking filter to the block boundary according to the strength determined by the filter strength determining unit, and

the controller controls the filtering unit so that, when the filter strength determining unit determines that strong filtering is to be applied, a clipping process is applied to the deblocking filter with respect to the luminance components of the image generated by the decoding unit.

17. The image processing device according to claim 16, wherein

the filter strength determining unit determines the strength of the deblocking filter using a plurality of lines as processing units.

18. The image processing device according to claim 17, wherein

the filter strength determining unit determines the strength of the deblocking filter using four lines as the processing units.

19. The image processing device according to claim 17, further comprising:

a filtering necessity determining unit that determines whether the deblocking filter is to be applied to the block boundary using a plurality of lines as processing units, wherein

the filter strength determining unit determines the strength of the deblocking filter when the filtering necessity determining unit determines that the deblocking filter is to be applied.

20. An image processing method for allowing an image processing device to execute:

applying a deblocking filter to a block boundary according to a strength of the deblocking filter applied to the block boundary which is a boundary between a block of an image locally decoded when an image is encoded and an adjacent block adjacent to the block;

controlling so that, when strong filtering is applied as the strength of the deblocking filter, a clipping process is applied to the deblocking filter with respect to luminance components of the locally decoded image; and

encoding the image in units each having a layer structure using an image to which the deblocking filter is applied.