Method and system for motion estimation using chrominance information

• US 20060188018A1
• Filed: 08/18/2005
• Published: 08/24/2006
• Est. Priority Date: 02/22/2005
• Status: Active Grant

• Current Assignee: Sunplus Technology Co., Ltd
• Original Assignee: Sunplus Technology Co., Ltd
• Inventors: Lin, Chun-Hung
• Granted Patent: US 7,760,807 B2
• Time in Patent Office: Days
• US Class Current: 375/240.160
• CPC Class Codes: H04N 19/102 characterised by the element, parameter or selection affected or controlled by the adaptive coding
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/196 being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters processing of motion vectors H04N19/513
• CPC Class Codes: H04N 19/198 including smoothing of a sequence of encoding parameters, e.g. by averaging, by choice of the maximum, minimum or median value
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation

Abstract

A method and system for motion estimation using chrominance information, which is based on each block of a current frame to find a corresponding block from a previous frame within a search area and accordingly determines a motion vector and includes first separately computing luminance differences and chrominance differences between luminance and chrominance of a target block in a current frame and luminance and chrominance of candidate blocks in a search range of a previous frame, next adjusting the luminance differences based on the first chrominance differences and the second chrominance differences and outputting adjusted luminance differences; and finally finding a minimum one among the adjusted luminance differences and accordingly determining the motion vector.

Claims

1. A system for motion estimation using chrominance information, which is based on each block of a current frame to find a corresponding block from a previous frame and accordingly determines a motion vector, the system comprising:

a luminance difference computation unit, which computes luminance differences between a luminance of a target block in a current frame and luminance of candidate blocks in a previous frame;

a first chrominance difference computation unit, which computes first chrominance differences between a first chrominance of the target block in the current frame and first chrominance of the candidate blocks in the previous frame;

a second chrominance difference computation unit, which computes second chrominance differences between a second chrominance of the target block in the current frame and second chrominance of the candidate blocks in the previous frame;

a chrominance distortion detection unit, which is based on the first chrominance differences and the second chrominance differences to adjust the luminance differences and to accordingly output adjusted luminance differences; and

a difference comparison unit, which finds a minimum one among the adjusted luminance differences and accordingly determines the motion vector.

2. The system as claimed in claim 1, wherein when a first chrominance difference or a second chrominance difference is greater than a predetermined chrominance threshold, the chrominance distortion detection unit adjusts a luminance difference corresponding to the first chrominance difference or the second chrominance difference into a maximum luminance difference to output;

and conversely, the luminance difference is directly output.

3. The system as claimed in claim 1, wherein when a first chrominance difference or a second chrominance difference is greater than a predetermined chrominance threshold and an average Q of the previous frame is greater than a predetermined quantization threshold, the chrominance distortion detection unit adjusts a luminance difference corresponding to the first chrominance difference or the second chrominance difference into a maximum luminance difference to output;

otherwise, the luminance difference is directly output.

4. The system as claimed in claim 1, wherein the first chrominance corresponds to chrominance U and the second chrominance corresponds to chrominance V.

5. The system as claimed in claim 1, wherein the blocks of current frame and previous frame are macroblocks.

6. The system as claimed in claim 1, wherein the blocks of current frame and previous frame are subblocks of macroblocks.

7. A method for motion estimation using chrominance information, which is based on each block of a current frame to find a corresponding block from a previous frame and accordingly determines a motion vector, the method comprising the steps:

(A) computing luminance differences between a luminance of a target block in a current frame and luminance of candidate blocks in a search range of a previous frame;

(B) computing first chrominance differences between a first chrominance of the target block in the current frame and first chrominance of the candidate blocks in the previous frame;

(C) computing second chrominance differences between a second chrominance of the target block in the current frame and second chrominance of the candidate blocks in the previous frame;

(D) adjusting the luminance differences based on the first chrominance differences and the second chrominance differences and outputting adjusted luminance differences; and

(E) finding a minimum one among the adjusted luminance differences and accordingly determining the motion vector.

8. The method as claimed in claim 7, wherein in step (D), when a first chrominance difference or a second chrominance difference is greater than a predetermined chrominance threshold, a luminance difference corresponding to the first chrominance difference or the second chrominance difference is adjusted into a maximum luminance difference to output;

otherwise, the luminance difference is directly output.

9. The method as claimed in claim 7, wherein in step (D), when a first chrominance difference or a second chrominance difference is greater than a predetermined chrominance threshold and an average Q of the previous frame is greater than a predetermined quantization threshold, a luminance difference corresponding to the first chrominance difference or the second chrominance difference is adjusted into a maximum luminance difference to output;

otherwise, the luminance difference is directly output.

10. The method as claimed in claim 7, wherein the first chrominance corresponds to chrominance U and the second chrominance corresponds to chrominance V.

11. The system as claimed in claim 7, wherein the blocks of current frame and previous frame are macroblocks.

12. The system as claimed in claim 7, wherein the blocks of current frame and previous frame are subblocks of macroblocks.