Image processing device and method

• US 9,317,933 B2
• Filed: 04/27/2012
• Issued: 04/19/2016
• Est. Priority Date: 05/27/2011
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Sato, Kazushi
• Primary Examiner(s): Patel, Kanjibhai
• Application Number:
  US14/112,788
• Publication Number:
  US 20140050413A1
• Time in Patent Office: 1,453 Days
• Field of Search: 382232-233, 382/251, 382/260
• US Class Current: 1/1
• CPC Class Codes: G06T 9/00 Image coding bandwidth or redundancy reduction for static pictures H04N1/41; coding or decoding of static colour picture signals H04N1/64; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00
• 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 19/157 Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• CPC Class Codes: H04N 19/86 involving reduction of coding artifacts, e.g. of blockiness

Abstract

The present technique relates to image processing devices and methods for enabling more appropriate removals of block distortions. When the difference between the quantization parameter QPc of a current region C and the quantization parameter QPN of a neighboring region N is determined to be larger than a predetermined threshold value, a deblocking filter adjusts the deblocking filtering operation so that stronger filtering is performed on a boundary between the current region and the neighboring region. This disclosure can be applied to image processing devices, for example.

Claims

1. An image processing device comprising:

a decoding unit configured to decode a bit stream encoded in a unit having a hierarchical structure, and generate an image;

a filtering unit configured to perform a filtering operation on the image generated by the decoding unit; and

a filter adjustment unit configured to adjust a parameter of the filtering unit so as to perform a first filtering operation, which is stronger in strength than a second filtering operation, on a boundary between a current region to be processed in the image generated by the decoding unit and a neighboring region adjacent to the current region, when a difference value between a quantization parameter of the current region and a quantization parameter of the neighboring region is larger than a threshold value.

2. The image processing device according to claim 1, wherein the filter adjustment unit controls the filtering unit to select the one of the first filtering operation and the second filtering operation.

3. The image processing device according to claim 1, wherein the filter adjustment unit adjusts the parameter of the filtering unit when the boundary is a boundary of a region in which a quantization parameter can be set.

4. The image processing device according to claim 1, wherein the parameter of the filtering unit is a boundary strength value, and the filter adjustment unit adds 1 to the boundary strength value, and sets the resultant value as the boundary strength value.

5. The image processing device according to claim 1, wherein the parameter of the filtering unit is a boundary strength value, and the filter adjustment unit sets 4 as the boundary strength value.

6. The image processing device according to claim 1, wherein the parameter of the filtering unit is a threshold value α

and a threshold value β

, and the filter adjustment unit associates the threshold value α and

the threshold value β

with “

QP+Δ

(Δ

>

0)”

, instead of a corresponding quantization parameter QP.

7. The image processing device according to claim 1, wherein the parameter of the filtering unit is a quantization parameter value, and the filter adjustment unit uses the larger one of the quantization parameter of the current region and the quantization parameter of the neighboring region as the parameter of the filtering unit.

8. The image processing device according to claim 1, wherein the parameter of the filtering unit is a quantization parameter value, and, when one of the current region and the neighboring region is in an uncompressed mode, the filter adjustment unit uses the quantization parameter of the other one of the current region and the neighboring region as the parameter of the filtering unit.

9. The image processing device according to claim 1, wherein the parameter of the filtering unit is a quantization parameter value, and the filter adjustment unit corrects the quantization parameters of the current region and the neighboring region by using a DC component of a quantization matrix, and determines the parameter of the filtering unit by using the corrected quantization parameters.

10. The image processing device according to claim 1, wherein the parameter of the filtering unit is a quantization parameter value, and, when at least one region of the current region and the neighboring region does not have an orthogonal transform coefficient, the filter adjustment unit determines the parameter of the filtering unit by using, as the quantization parameter of the at least one region, 0, a quantization parameter used in a region immediately before the at least one region, a predicted quantization parameter value for a region immediately before the at least one region, or a quantization parameter for a slice to which the at least one region belongs.

11. The image processing device according to claim 1, wherein the threshold value is set as a value that varies between a filtering operation in a horizontal direction and a filtering operation in a vertical direction.

12. The image processing device according to claim 1, wherein the threshold value is set as a value that varies with the size of the current region.

13. The image processing device according to claim 12, wherein the threshold value is set as a value that becomes smaller as the size of the current region becomes larger.

14. The image processing device according to claim 1, wherein the filter adjustment unit controls the filtering unit to perform the first filtering operation on a luminance component of the image generated by the decoding unit.

15. The image processing device according to claim 1, further comprising a difference value calculation unit configured to calculate the difference value between the quantization parameter of the current region and the quantization parameter of the neighboring region.

16. An image processing method comprising:

generating an image by decoding a bit stream encoded in a unit having a hierarchical structure;

when a difference value between a quantization parameter of a current region to be processed in the generated image and a quantization parameter of a neighboring region adjacent to the current region is larger than a threshold value, adjusting a filter parameter so as to perform a first filtering operation, which is stronger in strength than a second filtering operation, on a boundary between the current region and the neighboring region; and

performing the first filtering operation on the generated image,

the image generating, the parameter adjusting, and the first filtering operation being performed by an image processing device.

17. An image processing device comprising:

a filtering unit configured to perform a filtering operation on a locally decoded image when an image is encoded;

a filter adjustment unit configured to adjust a parameter of the filtering unit so as to perform a first filtering operation, which is stronger in strength than a second filtering operation, on a boundary between a current region to be processed in the image and a neighboring region adjacent to the current region, when a difference value between a quantization parameter of the current region and a quantization parameter of the neighboring region is larger than a threshold value; and

an encoding unit configured to perform encoding in a unit having a hierarchical structure by using a predicted image that is the image subjected to the filtering operation.

18. An image processing method comprising:

adjusting a filter parameter so as to perform a first filtering operation, which is stronger in strength than a second filtering operation, on a boundary between a current region to be processed in an image and a neighboring region adjacent to the current region, when a difference value between a quantization parameter of the current region and a quantization parameter of the neighboring region is larger than a threshold value;

performing the first filtering operation on a locally decoded image when the image is encoded; and

performing encoding in a unit having a hierarchical structure by using a predicted image that is the image subjected to the first filtering operation,

the parameter adjusting, the first filtering operation, and the encoding being performed by an image processing device.