System and methods for persona identification using combined probability maps

1. A method comprising:

obtaining at least one frame of pixel data and corresponding image depth data;

processing the at least one frame of pixel data and the corresponding image depth data with a plurality of persona identification modules to generate a corresponding plurality of persona probability maps, wherein the plurality of persona probability maps includes a hair-identification-module persona probability map, and wherein the plurality of persona identification modules comprises a hair-identification module for generating the hair-identification-module probability map at least in part by:

identifying a plurality of pixel columns that cross an identified head contour; and

for each pixel column in the plurality of pixel columns:

performing a color-based segmentation of the pixels in the pixel column into a foreground segment, a hair segment, and a background segment; and

assigning the pixels in the hair segment an increased foreground-probability value in the hair-identification-module persona probability map;

combining the plurality of persona probability maps to obtain an aggregate persona probability map; and

generating a persona image by extracting pixels from the at least one frame of pixel data based on the aggregate persona probability map.

2. The method of claim 1 , wherein:

the at least one frame of pixel data comprises two frames of stereo pixel data; and

the corresponding image depth data is obtained from disparity data generated by a stereo disparity module.

3. The method of claim 2 , wherein processing the at least one frame of pixel data and the corresponding image depth data comprises:

generating a foreground-background map from the disparity data by designating pixels having a disparity value above a threshold as foreground pixels.

4. The method of claim 2 , wherein:

the disparity data comprises a plurality of disparity values for each pixel, each of the plurality of disparity values having an associated confidence value; and

processing the at least one frame of pixel data and the corresponding image depth data comprises generating a foreground-background map from the disparity data by identifying pixels having a cumulative confidence measure above a threshold as foreground pixels.

5. The method of claim 1 , wherein processing the at least one frame of pixel data and the corresponding image depth data comprises converting the corresponding image depth data to a foreground-background map using a thresholding operation.

6. The method of claim 5 , wherein processing the at least one frame of pixel data and the corresponding image depth data further comprises performing a distance transform on the foreground-background map to obtain a persona probability map.

7. The method of claim 1 , wherein extracting pixels is performed using a graph cut module.

8. The method of claim 1 , wherein the aggregate persona probability map is formed by combining the plurality of persona probability maps using predetermined weights.

9. A method comprising:

obtaining at least one frame of pixel data and corresponding image depth data;

processing the corresponding image depth data to generate a foreground-background map;

processing the at least one frame of pixel data and the foreground-background map to generate a plurality of persona probability maps at least in part through use of a hair-identification module, wherein the plurality of persona probability maps includes a hair-identification-module persona probability map that is generated by the hair-identification module at least in part by:

identifying a plurality of pixel columns that cross an identified head contour; and

for each pixel column in the plurality of pixel columns:

performing a color-based segmentation of the pixels in the pixel column into a foreground segment, a hair segment, and a background; and

assigning the pixels in the hair segment an increased foreground-probability value in the hair-identification-module persona probability map;

combining the plurality of persona probability maps to obtain an aggregate persona probability map; and

generating a persona image by extracting pixels from the at least one frame of pixel data based on the aggregate persona probability map.

10. The method of claim 9 , wherein the foreground-background map is generated from a disparity data volume.

11. The method of claim 9 , wherein processing the at least one frame of pixel data and the foreground-background map to generate a plurality of persona probability maps comprises:

performing a distance transform on the foreground-background map to generate a persona probability map.

12. An apparatus comprising:

a foreground-background module configured to generate a foreground-background map based on image depth data;

a plurality of persona identification modules configured to generate a corresponding plurality of persona probability maps, wherein the plurality of persona identification modules comprises a hair-identification module, wherein the plurality of persona probability maps includes a hair-identification-module persona probability map that is generated by the hair-identification module at least in part by:

identifying a plurality of pixel columns that cross an identified head contour; and

for each pixel column in the plurality of pixel columns:

performing a color-based segmentation of the pixels in the pixel column into a foreground segment, a hair segment, and a background segment; and

assigning the pixels in the hair segment an increased foreground-probability value in the hair-identification-module persona probability map;

a combiner module configured to generate an aggregate persona probability map based on the plurality of persona probability maps; and

a persona extraction module configured to generate a persona image by extracting pixels from at least one frame of pixel data based on the aggregate persona probability map.

13. The method of claim 1 , further comprising converting the head contour into a multi-segment polygon that approximates the head contour, the multi-segment polygon being formed of multiple head-contour segments, wherein identifying the plurality of pixel columns that cross the identified head contour comprises identifying pixel columns that cross one of the head-contour segments.

14. The method of claim 1 , wherein performing a color-based segmentation comprises performing a color-based segmentation using a clustering algorithm.

15. The method of claim 14 , wherein the clustering algorithm is a k-means algorithm with k=3.

16. The method of claim 1 , wherein performing the color-based segmentation of the pixels in a given pixel column into the foreground segment, the hair segment, and the background segment of the given pixel column comprises:

identifying an average foreground-pixel color, an average hair-pixel color, and an average background-pixel color for the given pixel column; and

identifying the foreground segment, the hair segment, and the background segment of the given pixel column using a clustering algorithm to cluster the pixels in the given pixel column around the identified average foreground-pixel color, the identified average hair-pixel color, and the identified average background-pixel color for the given pixel column, respectively.

17. The method of claim 16 , wherein:

identifying the average foreground-pixel color for the given pixel column comprises identifying the average foreground-pixel color for the given pixel column based on a first set of pixels at an innermost end of the given pixel column;

identifying the average hair-pixel color for the given pixel column comprises identifying the average hair-pixel color for the given pixel column based on a second set of pixels that includes a point where the given pixel column crosses the identified head contour; and

identifying the average background-pixel color for the given pixel column comprises identifying the average background-pixel color for the given pixel column based on a third set of pixels at an outermost end of the given pixel column.

18. The method of claim 1 , further comprising, for each pixel column in the plurality of pixel columns:

assigning the pixels in the foreground and background segments an equal probability of being in the foreground and being in the background in the hair-identification-module persona probability map.

19. The method of claim 1 , wherein assigning the pixels in the hair segment an increased foreground-probability value in the hair-identification-module persona probability map comprises:

assigning a first value to the pixels in the hair segment in the hair-identification-module persona probability map; and

assigning a second value to the pixels in the foreground and background segments in the hair-identification-module persona probability map, wherein the first value corresponds to a higher probability of being a foreground pixel than does the second value.