Image processing device and method

• US 10,419,756 B2
• Filed: 06/15/2017
• Issued: 09/17/2019
• Est. Priority Date: 04/06/2012
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Lu, Shuo, Ikeda, Masaru
• Primary Examiner(s): Senfi, Behrooz M
• Application Number:
  US15/624,457
• Publication Number:
  US 20170289544A1
• Time in Patent Office: 824 Days
• Field of Search: 37524029
• 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 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness

Abstract

An image processing device and method capable of suppressing block noise.

A β LUT_input calculation unit and a clipping unit calculate β LUT_input that is a value input to an existing β generation unit and an extended β generation unit. When the value of β LUT_input qp from the clipping unit is equal to or less than 51, the existing β generation unit calculates β using the LUT defined in the HEVC method and supplies the calculated β to a filtering determination unit. When the value of β LUT_input qp from the clipping unit is larger than 51, the extended β generation unit calculates extended β and supplies the calculated β to the filtering determination unit. The device can be applied to an image processing device, for example.

Claims

1. An image processing device, comprising:

a decoder configured to generate a decoded image by decoding an encoded stream; and

a filter configured to apply a deblocking filter to pixels neighboring a block boundary within the decoded image using a filter parameter set based on a quantization parameter, the filter parameter being set to be greater than 12 in case that the quantization parameter is equal to 47, wherein

the filter parameter is used during clipping of filtered pixels output by the deblocking filter, and

the filter parameter being set by a look-up table based on a value of the quantization parameter when the value of the quantization parameter is equal to or less than 53.

2. The image processing device according to claim 1, wherein the quantization parameter is an average of a first quantization parameter and a second quantization parameter between a first block and a second block at the block boundary.

3. The image processing device according to claim 2, wherein the filter is configured to apply the deblocking filter to the pixels within the decoded image using the filter parameter set according to an extended range, the range being within the extended range.

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

the deblocking filter comprises a weak filter with a first strength and a strong filter with a second strength stronger than the first strength, and

the filter parameter is a parameter used during selection of either one of the weak filter and the strong filter or during clipping of the filtered pixels after application of the strong filter.

5. The image processing device according to claim 1, wherein the block boundary is a boundary of a transformer unit or of a prediction unit.

6. The image processing device according to claim 1, wherein the decoder comprises:

an arithmetic decoding unit configured to perform an arithmetic decoding process on the encoded stream to generate quantized data;

an inverse quantization unit configured to perform an inverse quantization process on the quantized data to generate transformation coefficient data; and

an inverse orthogonal transformation unit to configured to perform an inverse orthogonal transformation process on the transformation coefficient data.

7. The image processing device according to claim 6, wherein the decoder is configured to decode the encoded stream according to coding units derived from dividing a largest coding unit recursively.

8. The image processing device according to claim 7, wherein the coding units are derived from dividing the largest coding unit in accordance with a quad-tree structure.

9. The image processing device according to claim 8, wherein the largest coding unit is a coding unit in the top level of the quad-tree structure.

10. The image processing device according to claim 9, wherein

the largest coding unit is a block of fixed size under sequence level, and

the coding unit is a block of variable size.

19. The image processing device according to claim 1, wherein the filter parameter is set by evaluating the function of the quantization parameter as follows:

tc(qp)=max(round(0.5*qp−

13.5),i),

wherein tc is the filter parameter and qp is the quantization parameter.

11. An image processing method, comprising:

generating a decoded image by decoding an encoded stream; and

applying a deblocking filter to pixels neighboring a block boundary within the decoded image using a filter parameter set based on a quantization parameter, the filter parameter being set to be greater than 12 in case that the quantization parameter is equal to 47, wherein

the filter parameter is used during clipping of filtered pixels output by the deblocking filter, and

the filter parameter being set by a look-up table based on a value of the quantization parameter when the value of the quantization parameter is equal to or less than 53.

12. The image processing method according to claim 11, wherein the quantization parameter is an average of a first quantization parameter and a second quantization parameter between a first block and a second block at the block boundary.

13. The image processing method according to claim 12, wherein the deblocking filter is applied to the pixels within the decoded image using the filter parameter set according to an extended range, the range being within the extended range.

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

the deblocking filter comprises a weak filter with a first strength and a strong filter with a second strength stronger than the first strength, and

the filter parameter is a parameter used during selection of either one of the weak filter and the strong filter or during clipping of the filtered pixels after application of the strong filter.

15. The image processing method according to claim 11, wherein the block boundary is a boundary of a transformer unit or of a prediction unit.

16. The image processing method according to claim 11, wherein generating the decoded image comprises:

performing an arithmetic decoding process on the encoded stream to generate quantized data;

performing an inverse quantization process on the quantized data to generate transformation coefficient data; and

performing an inverse orthogonal transformation process on the transformation coefficient data.

17. The image processing method according to claim 16, wherein generating the decoded image further includes decoding the encoded stream according to coding units derived from dividing a largest coding unit recursively.

20. The image processing method according to claim 11, wherein the filter parameter is set by evaluating the function of the quantization parameter as follows:

tc(qp)=max(round(0.5*qp−

13.5),1),

wherein tc is the filter parameter and qp is the quantization parameter.

18. An image processing device, comprising:

circuitry configured to;

decode an encoded stream to generate a decoded image; and

apply a deblocking filter to pixels neighboring a block boundary within the decoded image using a filter parameter set based on a quantization parameter, the filter parameter being set to be greater than 12 in case that the quantization parameter is equal to 47, wherein

the filter parameter is used during clipping of filtered pixels output by the deblocking filter, and

the filter parameter being set by a look-up table based on a value of the quantization parameter when the value of the quantization parameter is equal to or less than 53.

21. The image processing device according to claim 18, wherein the filter parameter is set by evaluating the function of the quantization parameter as follows:

tc(qp)=max(round(0.5*qp−

13.5),1),

wherein tc is the filter parameter and qp is the quantization parameter.