Method and apparatus for nonlinear interpolation color conversion using look up tables

1. A method of mapping between color gamuts comprising:

obtaining, by an apparatus, a source image having a plurality of source color gamut pixels in a source color gamut;

converting, by the apparatus, the plurality of source color gamut pixels to a plurality of corresponding narrower target color gamut pixels using non-linear interpolation of a plurality of output pixel values from a reduced 3 dimensional (3-D) look-up table (LUT) corresponding to a target color gamut, wherein the reduced 3-D LUT comprises a plurality of displayable target color values representing vertices of a plurality of sub-cubes that represent less than all entries within the target color gamut; and

providing, for display, by the apparatus, the plurality of corresponding target color gamut pixels on a target color gamut display.

2. The method of claim 1 , wherein the converting the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels comprises performing a first non-linear interpolation for a plurality of first pixel values from the reduced 3-D LUT that is different from a second non-linear interpolation for a plurality of second pixel values from the reduced 3-D LUT.

3. The method of claim 2 , wherein the plurality of first pixel values from the reduced 3-D LUT correspond to vertices of a sub-cube within the target color gamut and wherein the converting the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels further comprises:

determining, based on the plurality of first pixel values from the reduced 3-D LUT, a set of polynomial coefficients for the sub-cube, and

wherein the performing the first non-linear interpolation is based on the set of polynomial coefficients.

4. The method of claim 3 , wherein the performing the first non-linear interpolation based on the set of polynomial coefficients is prior to performing a tetrahedral interpolation calculation or a tri-linear interpolation calculation.

5. The method of claim 3 , wherein a graphics driver calculates the set of polynomial coefficients by performing a Taylor Series transform based on the vertices of the sub-cube within the target color gamut.

6. The method of claim 2 , wherein the first non-linear interpolation is a piecewise linear curve or a polynomial equation.

7. The method of claim 1 , wherein the converting the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels is performed by a 3-D engine.

8. The method of claim 1 , wherein the converting the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels is performed by a video encoder, and

wherein the obtaining the plurality of source color gamut pixels comprises obtaining the plurality of source color gamut pixels from a server via an internet connection.

9. The method of claim 1 , the converting the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels is performed by a display engine, and

wherein the display engine performs tone mapping operations for the target color gamut display.

10. An apparatus comprising:

non-linear interpolation color conversion logic configured to:

obtain a source image having a plurality of source color gamut pixels in a source color gamut;

convert the plurality of source color gamut pixels to a plurality of corresponding narrower target color gamut pixels using non-linear interpolation of a plurality of output pixel values from a reduced 3-D LUT corresponding to a target color gamut, the 3-D LUT comprising a plurality of displayable target color values representing vertices of a plurality of sub-cubes that represent less than all entries within the target color gamut; and

provide for display the plurality of corresponding target color gamut pixels on a target color gamut display.

11. The apparatus of claim 10 , wherein the non-linear interpolation color conversion logic converts the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels by performing a first non-linear interpolation for a plurality of first pixel values from the reduced 3-D LUT that is different from a second non-linear interpolation for a plurality of second pixel values from the reduced 3-D LUT.

12. The apparatus of claim 11 , wherein the plurality of first pixel values from the reduced 3-D LUT correspond to vertices of a sub-cube within the target color gamut and wherein non-linear interpolation color conversion logic converts the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels by:

determining, based on the plurality of first pixel values from the reduced 3-D LUT, a set of polynomial coefficients for the sub-cube, and

wherein the performing the first non-linear interpolation is based on the set of polynomial coefficients.

13. The apparatus of claim 12 , wherein the non-linear interpolation color conversion logic performs the first non-linear interpolation prior to performing a tetrahedral interpolation calculation or a tri-linear interpolation calculation.

14. The apparatus of claim 12 , further comprising:

a processor comprising a graphics driver, wherein the graphics driver is configured to calculate the set of polynomial coefficients by performing a Taylor Series transform based on the vertices of the sub-cube within the target color gamut.

15. The apparatus of claim 12 , wherein the plurality of second pixel values from the reduced 3-D LUT correspond to vertices of a second sub-cube and wherein non-linear interpolation color conversion logic converts the plurality of source color gamut pixels to the plurality of corresponding target color gamut pixels by:

determining, based on the plurality of second pixel values from the reduced 3-D LUT, a second set of polynomial coefficients for the second sub-cube, wherein the second set of polynomial coefficients is different from the set of polynomial coefficients; and

performing the second non-linear interpolation based on the second set of polynomial coefficients.

16. The apparatus of claim 11 , wherein the first non-linear interpolation is a piecewise linear curve or a polynomial equation.

17. The apparatus of claim 10 , further comprising:

a video encoder, wherein the video encoder comprises the non-linear interpolation color conversion logic, and wherein the video encoder is configured to:

obtain the plurality of source color gamut pixels from a server via an internet connection.

18. The apparatus of claim 10 , further comprising:

a display engine, wherein the display engine comprises the non-linear interpolation color conversion logic, and wherein the display engine performs tone mapping operations for the target color gamut display.

19. The apparatus of claim 10 , further comprising:

a 3-D engine, wherein the 3-D engine comprises the non-linear interpolation color conversion logic; and

a texture cache, wherein the texture cache stores the reduced 3-D LUT corresponding to the target color gamut.

20. An integrated circuit comprising:

a first processor, wherein the first processor comprises:

non-linear interpolation color conversion logic configured to:

obtain a source image having a plurality of source color gamut pixels in a source color gamut;

obtain a reduced 3-D LUT corresponding to a target color gamut, the reduced 3-D LUT comprises a plurality of displayable target color values representing vertices of a plurality of sub-cubes;

select, on a pixel-by-pixel basis, a plurality of pixel values from the plurality of displayable target color values, a plurality of pixel values representing vertices of a sub-cube of the plurality of sub-cubes within the target color gamut;

determine, based on a non-linear interpolation of the vertices of the sub-cube, a set of polynomial coefficients for the sub-cube representing a Taylor Series transform;

convert, based on the set of polynomial coefficients for the sub-cube, the plurality of source color gamut pixels to a plurality of corresponding target color gamut pixels using the non-linear interpolation of the vertices of the sub-cube; and

provide, for display, the plurality of corresponding target color gamut pixels on a target color gamut display.