System and method for estimating view synthesis distortion

Patent metadata

Field	Value
Publication number	US-9699462-B2
Application number	US-201514588646-A
Country	US
Kind code	B2
Filing date	Jan 2, 2015
Priority date	Jan 3, 2014
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

System and method embodiments are provided for achieving improved View Synthesis Distortion (VSD) calculation and more accurate distortion estimation of encoded video frames. An embodiment method includes obtaining a depth map value for a video frame and determining a weighting factor for depth distortion in accordance with the depth map value. The weighting factor maps a pixel range of the depth map value to an output function having higher values for closer image objects and lower values for farther image objects. The VSD for the video frame is then calculated as a function of absolute horizontal texture gradients weighted by a depth distortion value and the weighting factor determined in accordance with the depth map value.

First claim

What is claimed is:

1. A method by a processor for estimating view synthesis distortion (VSD) for video coding, the method comprising:
obtaining a depth map value for a video frame;
determining a weighting factor for depth distortion in accordance with the depth map value; and
calculating, for the video frame, the VSD as a function of absolute horizontal texture gradients weighted by a depth distortion value and the weighting factor determined in accordance with the depth map value.

2. The method of claim 1 , wherein the weighting factor has a larger value when the depth map value has a corresponding larger value indicating a closer image object, and has a smaller value when the depth map value has a corresponding smaller value indicating a farther image object.

3. The method of claim 1 , wherein the weighting factor is a nonlinear function of the depth map value.

4. The method of claim 1 , wherein the weighting factor is a piecewise linear or nonlinear function of the depth map value.

5. The method of claim 1 , wherein the weighting factor is a look-up table with the depth map value as input.

6. The method of claim 1 , wherein the depth distortion value is calculated based on the depth map value and a reconstructed depth map value after compression of the video frame.

7. The method of claim 1 , wherein the weighting factor is determined in accordance with the video frame, and wherein the method further includes varying the weighting factor based on the video frame under consideration.

8. The method of claim 1 , wherein the function for calculating the VSD is determined in accordance with the video frame, and wherein the method further includes varying the function for calculating the VSD based on the video frame under consideration.

9. The method of claim 1 , wherein the processor is part of a video encoder or decoder in one of a user device and a network device.

10. A method by a processor for estimating view synthesis distortion (VSD) for video coding, the method comprising:
obtaining a depth map value for a video frame;
determining a weighting factor, wherein the weighting factor maps a pixel range of the depth map value to an output function having higher values for closer image objects and lower values for farther image objects; and
calculating the VSD as a product of a term for horizontal texture distortion and a term for depth distortion weighted by the weighting factor.

11. The method of claim 10 , wherein the weighting factor is a piecewise linear function, g(s D (x,y)), obtained as:
g ( s D ( x,y )) =d, if s D ( x,y ) ≧e,
g ( s D ( x,y ))=( s D ( x,y )− a ) /b+c, if f<s D ( x,y ) <e, and

g ( s D ( x,y ))=1, if s D ( x,y ) ≦f,

and wherein a, b, c, d, e, and f are variables selected appropriately to determine a suitable mapping between the pixel range of the depth map value to the output function of the weighting factor.

12. The method of claim 10 , wherein the weighting factor is obtained based on a logarithm function of the depth map value.

13. The method of claim 10 , wherein the weighting factor is obtained as max(alog b (S D (x,y)+e)+c,d) where S D (x,y) is the depth map value, and wherein a, b, e, c, and d are variables selected appropriately to determine a suitable mapping between the pixel range of the depth map value to the output function of the weighting factor.

14. The method of claim 10 , wherein the weighting factor is obtained as max((S D (x,y)−a)/c, b) where S D (x,y) is the depth map value, and wherein a, c, and b are variables selected appropriately to determine a suitable mapping between the pixel range of the depth map value to the output function of the weighting factor.

15. The method of claim 10 , wherein the weighting factor is obtained as:
f ( S D ( x,y )) =d if S D ( x,y ) >e, and
f ( S D ( x,y ))=max(( S D ( x,y )−α) /c, b ) if S D ( x,y ) <=e,

and wherein a, b, c, d, and e are variables selected appropriately to determine a suitable mapping between the pixel range of the depth map value to the output function of the weighting factor.

16. The method of claim 10 , wherein the weighting factor is calculated by a mapping of predetermined pixel ranges of the depth map value to weighting factor values.

17. The method of claim 10 , wherein the processor is located at one of a user device and a network device.

18. An apparatus for estimating view synthesis distortion (VSD), the apparatus comprising:
at least one processor;
a non-transitory computer readable storage medium storing programming for execution by the at least one processor, the programming including instructions to:
obtain a depth map value for a video frame;
determine a weighting factor for depth distortion in accordance with the depth map value; and
calculate, for the video frame, the VSD as a function of a sum of absolute horizontal texture gradients weighted by a depth distortion value and the weighting factor for depth distortion determined in accordance with the depth map value.

19. The apparatus of claim 18 , wherein the weighting factor has a larger value when the depth map value has a corresponding larger value indicating a closer image object, and has a smaller value when the depth map value has a corresponding smaller value indicating a farther image object.

20. The apparatus of claim 18 , wherein the apparatus is located at one of a user device and a network device.

Assignees

• Futurewei Technologies Inc
• Univ Santa Clara

Inventors

• Gu Zhouye
• Zheng Jianhua
• Ling Nam
• Zhang Chen-Xiong

Classifications

• H04N19/154

  Measured or subjectively estimated visual quality after decoding, e.g. measurement of distortion (use of rate-distortion criteria H04N19/147) · CPC title

• H04N19/503 Primary

  involving temporal prediction (adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109) · CPC title

• H04N19/136 Primary

  Incoming video signal characteristics or properties · CPC title