Contour free point operation for video skin tone correction
A method for a color tone correction is disclosed. The method generally includes the steps of (A) generating a plurality of first intermediate components by scaling a plurality of first color components towards a first ideal color, wherein the first color components (i) are for a first plurality of pixels in an input video signal and (ii) fall inside a first region of a color space, (B) generating a plurality of first corrected components by adjusting the first intermediate components such that a first mapping of the first color components to the first corrected components is both (i) continuous in the color space and (ii) non-overlapping in the color space and (C) generating an output video signal by combining the first corrected components with a plurality of unaltered color components, wherein the unaltered color components (i) are for a second plurality of the pixels and (ii) fall outside the first region.
1. A method for a color tone correction, comprising the steps of:
(A) generating a plurality of first intermediate components by scaling a plurality of first color components towards a first ideal color, wherein said first color components (i) are for a first plurality of pixels in an input video signal and (ii) fall inside a first region of a color space;
(B) generating a plurality of first corrected components by adjusting said first intermediate components such that a first mapping of said first color components to said first corrected components is both (i) continuous in said color space and (ii) non-overlapping in said color space; and
(C) generating an output video signal by combining said first corrected components with a plurality of unaltered color components, wherein said unaltered color components (i) are for a second plurality of said pixels and (ii) fall outside said first region.
2. The method according to claim 1 , wherein each respective one of said first corrected components is generated from a single one of said first color components.
3. The method according to claim 1 , further comprising the step of:
separating said first color components into (i) a plurality of first color values and (ii) a plurality of second color values.
4. The method according to claim 3 , wherein step (A) comprises the sub-steps of:
generating a plurality of first scaled values by scaling said first color values; and
generating a plurality of second scaled values by scaling said second color values independently of scaling said first color values.
5. The method according to claim 4 , wherein step (B) comprises the sub-steps of:
generating a plurality of first corrected values by adjusting said first scaled values based on said second scaled values; and
generating a plurality of second corrected values by adjusting said first scaled values based on said first corrected values, wherein said first corrected components comprises said first corrected values and said second corrected values respectively.
6. The method according to claim 5 , wherein step (B) comprises the sub-steps of:
generating a first adjustment component as a first function of said second color value, wherein generation of said first corrected value is based on said first adjustment component; and
generating a second adjustment component as a second function of said first corrected value, wherein generation of said second corrected value is based on said second adjustment component.
7. The method according to claim 1 , wherein said first region comprises:
a central region inside said first region; and
a boundary region (i) inside said first region and (ii) outside said central region.
8. The method according to claim 7 , wherein step (A) comprises the sub-steps of:
scaling said first color components within said central region by a first scale factor; and
scaling said first color components within said boundary region by a second scale factor, wherein said second scale factor is smaller than said first scale factor.
9. The method according to claim 1 , further comprising the step of:
maintaining a plurality of luminance components for said pixels unchanged during said color tone correction.
10. The method according to claim 1 , further comprising the steps of:
generating a plurality of second intermediate components by scaling a plurality of second color components towards a second ideal color, wherein said second color components (i) are for a third plurality of said pixels and (ii) fall inside a second region of said color space; and
generating a plurality of second corrected components by adjusting said second intermediate components such that a second mapping of said second color components to said second corrected components is both (i) continuous in said color space and (ii) non-overlapping in said color space, wherein
generation of said output video signal further combines said second corrected components.
11. A system comprising:
a correction module configured to (A) generate a plurality of first intermediate components by scaling a plurality of first color components towards a first ideal color, wherein said first color components (i) are for a first plurality of pixels in an input video signal and (ii) fall inside a first region of a color space and (B) generate a plurality of first corrected components by adjusting said first intermediate components such that a first mapping of said first color components to said first corrected components is both (i) continuous in said color space and (ii) non-overlapping in said color space; and
a conversion module configured to generate an output video signal by combining said first corrected components with a plurality of unaltered color components, wherein said unaltered color components (i) are for a second plurality of said pixels and (ii) fall outside said first region.
12. The system according to claim 11 , wherein each respective one of said first corrected components is generated from a single one of said first color components.
13. The system according to claim 11 , wherein said conversion module comprises:
a combination module configured to generate said output video signal; and
a color space converter module configured to convert said output video signal to an RGB color space.
14. The system according to claim 11 , wherein said correction module comprises:
a separation module configured to separate said first color components from said unaltered color components; and
a first mapping module configured to generate said first corrected components for said first region.
15. The system according to claim 14 , wherein said correction module further comprises a second mapping module configured to generate said first corrected components for a second region in said color space.
16. The system according to claim 14 , wherein said first mapping module comprises:
a plurality of first lookup tables configured to generate said first intermediate components from said first color components; and
a plurality of second lookup tables configured to generate said first corrected components from said first intermediate components.
17. The system according to claim 14 , wherein said separation module comprises a lookup table configured to distinguish between said first color components and said unaltered color components.
18. The system according to claim 11 , wherein said first region is selected from a group of regions comprising (i) a skin tone region, (ii) a grass region, (iii) a water region and (iv) a sky region.
19. The system according to claim 11 , wherein said first region has a shape selected from a group of shapes comprises (i) a rectangular shape, (ii) a triangular shape, (iii) an oval shape, (iv) a pie shape, (v) a hexagonal shape and (vi) an elliptical shape.
20. A system comprising:
means for generating a plurality of first intermediate components by scaling a plurality of first color components towards a first ideal color, wherein said first color components (i) are for a first plurality of pixels in an input video signal and (ii) fall inside a first region of a color space;
means for generating a plurality of first corrected components by adjusting said first intermediate components such that a first mapping of said first color components to said first corrected components is both (i) continuous in said color space and (ii) non-overlapping in said color space; and
means for generating an output video signal by combining said first corrected components with a plurality of unaltered color components, wherein said unaltered color components (i) are for a second plurality of said pixels and (ii) fall outside said first region.