System and method for estimating view synthesis distortion

Patent metadata

Field	Value
Publication number	US-10326995-B2
Application number	US-201715640290-A
Country	US
Kind code	B2
Filing date	Jun 30, 2017
Priority date	Jan 3, 2014
Publication date	Jun 18, 2019
Grant date	Jun 18, 2019

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 sample value for a video frame;
determining a weighting factor for depth distortion in accordance with the depth map sample 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 sample value.

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

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

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

6. The method of claim 1 , wherein the depth distortion value is calculated based on the depth map sample value and a reconstructed depth map sample 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 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 sample value for a video frame;
determining a weighting factor, wherein the weighting factor maps a pixel range of the depth map sample 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 sample 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 sample value.

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

15. The method of claim 10 , wherein the weighting factor is obtained as:
( S D ( x,y ))= d if S D ( x,y )> e , and
ƒ( S D ( x,y ))=max(( S D ( x,y )− a )/ 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 sample 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 sample value to weighting factor values.

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

18. An apparatus for estimating view synthesis distortion (VSD), the apparatus comprising:
a non-transitory computer readable storage medium comprising instructions; and
one or more processors in communication with the non-transitory computer readable storage medium, wherein the one or more processors execute the instructions to:
obtain a depth map sample value for a video frame;

determine a weighting factor for depth distortion in accordance with the depth map sample 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 sample value.

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

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

Assignees

• Futurewei Technologies Inc
• Univ Santa Clara

Inventors

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

Classifications

• H04N19/136 Primary

  Incoming video signal characteristics or properties · 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

• H04N19/154

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