Skin color cognizant GMA with luminance equalization

• US 20100194773A1
• Filed: 01/30/2009
• Published: 08/05/2010
• Est. Priority Date: 01/30/2009
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Daly, Scott J., Pan, Hao
• Granted Patent: US 8,238,654 B2
• Time in Patent Office: Days
• US Class Current: 345/590
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: H04N 1/628 Memory colours, e.g. skin or sky

Abstract

A method for mapping/enhancing the color of an image to be displayed on a display includes receiving an image having a plurality of pixels where each of the pixels has a plurality of color components. The image is processed using a pair of gamut color mapping operations in combination with skin-tone pixels detection to modify the image in a suitable manner for presentation on the display, wherein the technique includes color temperature compensation.

Claims

1. A method for modifying an image to be displayed on a display comprising:

(a) receiving an image calibrated to a first color gamut generally smaller than the color gamut of said display;

(b) filtering said image with a spatial filter to define regions including generally skin-tones in such a manner that the skin-tone regions of the image are modified in a manner different than generally non-skin-tone regions of said image are modified when displayed on said display;

(c) modifying a luminance of said generally skin-tone regions in a manner different than said generally non-skin-tone regions of said filtered image;

(d) displaying said modified luminance filtered image on said display.

2. The method of claim 1 wherein said filtering does not change the color temperature of said received image.

3. A method of claim 1 wherein said modified luminance raises the luminance of said skin-tone regions while reducing the luminance of said non-skin-tone-regions.

4. The method of claim 1 wherein said skin-tone regions are defined by a spatial low pass filter.

5. The method of claim 1 wherein said filtered image includes edges.

6. The method of claim 1 wherein said filtered image is defined using a edge preserving low pass filter.

7. The method of claim 1 wherein said spatial filter includes a region defined around a pixel of interest.

8. The method of claim 7 wherein said spatial filter determines pixels within said region that are sufficiently similar to said pixel of interest.

9. The method of claim 1 wherein said filtering includes a look-up table to further define said skin-tone regions.

10. The method of claim 1 wherein said filtering includes a spatial characteristics that determines whether proximate pixels have said skin-tones.

11. The method of claim 1 wherein said filtering includes a color space characteristic that determines if proximate pixels have said skin-tones.

12. The method of claim 1 wherein said image is separated into a base image and a residual image, said base image is said filtered and said residual image includes said higher frequency content.

13. The method of claim 1 wherein said lower frequency content is separated by edges.

14. The method of claim 1 wherein said higher frequency content includes high frequency details, noise, and artifacts.

15. The method of claim 1 wherein said filter includes a threshold.

16. The method of claim 1 wherein said threshold is based upon the content of said image.

17. A method for modifying an image to be displayed on a display comprising:

(a) receiving an image calibrated to a first color gamut generally smaller than the color gamut of said display;

(b) filtering said received image with a filter to define pixels including generally skin-tones in such a manner that the skin-tone pixels of the image are modified in a manner different than generally non-skin-tone pixels of said image are modified when displayed on said display, wherein said filtering is also performed in such a manner that a luminance of said generally skin-tone regions are filtered in a manner different than said generally non-skin-tone regions of said filtered image;

(c) displaying said filtered image on said display.

18. The method of claim 17 wherein said filtering is based upon a color temperature.

19. The method of claim 17 wherein said luminance of said non-skin-tone regions is lowered.

20. The method of claim 17 wherein said filtering adjusts the hue of the displayed image.

21. The method of claim 17 wherein said filtering distinguishes skin tones from at least one of whites and neutrals.

22. The method of claim 17 wherein said luminance of said skin tone regions is raised.

23. The method of claim 17 wherein said luminance of said skin tone regions and said non-skin tone regions are raised.

24. A method for modifying an image to be displayed on a display comprising:

(a) receiving an image calibrated to a first color gamut generally smaller than the color gamut of said display;

(b) decomposing said image into a lowpass image and a highpass image with a spatial filter;

(c) assigning for a plurality of pixels in said lowpass image a skin score;

(d) filtering said skin score with a lowpass filter to define regions including generally skin-tones in such a manner that the skin-tone regions of the image are modified in a manner different than generally non-skin-tone regions of said image are modified when displayed on said display;

(e) modifying a luminance of said generally skin-tone regions in a manner different than said generally non-skin-tone regions of said filtered image;

(f) displaying said modified luminance filtered image on said display.

25. The method of claim 24 wherein said filtering does not change the color temperature of said received image.

26. A method of claim 24 wherein said modified luminance raises the luminance of said skin-tone regions while reducing the luminance of said non-skin-tone-regions.

27. The method of claim 24 wherein said spatial filter includes a region defined around a pixel of interest.

28. The method of claim 24 wherein said filtering includes a spatial characteristics that determines whether proximate pixels have said skin-tones.

29. The method of claim 24 wherein said filtering includes a color space characteristic that determines if proximate pixels have said skin-tones.

30. The method of claim 24 wherein said threshold is based upon the content of said image.

31. A method for modifying an image to be displayed on a display comprising:

(a) receiving an image calibrated to a first color gamut generally smaller than the color gamut of said display;

(b) spatially decomposing said image into a lowpass image and a highpass image, where a plurality of pixels of said lowpass image are associated with a skin score;

(c) filtering said skin score with a lowpass filter to define regions including generally skin-tones in such a manner that the skin-tone pixels of the image are modified in a manner different than generally non-skin-tone pixels of said image are modified when displayed on said display;

(d) modifying a luminance of said generally skin-tone regions in a manner different than said generally non-skin-tone regions of said filtered image;

(e) displaying said filtered image on said display.

32. The method of claim 31 wherein said filtering is based upon a color temperature.

33. The method of claim 31 wherein said luminance of said non-skin-tone regions is lowered.

34. The method of claim 31 wherein said filtering adjusts the hue of the displayed image.

35. The method of claim 31 wherein said filtering distinguishes skin tones from at least one of whites and neutrals.

36. The method of claim 31 wherein said luminance of said skin tone regions is raised.

37. The method of claim 31 wherein said luminance of said skin tone regions and said non-skin tone regions are raised.