Converting color primaries and luminances of an input signalt to different color primaries and luminances for a display
AssigneeTP Vision Holding B.V.
InventorErno Hermanus Antonius Langendijk
Life of this patent
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Abstract
A color gamut mapping maps an input image signal which has input pixel colors defined by an input luminance and an input chromaticity into a mapped image signal which has corresponding mapped pixel colors defined by a mapped luminance and a mapped chromaticity for a display. The input pixel colors lie within the input color gamut different than the display color gamut. The desired mapped luminance may be retrieved by looking up stored desired luminance values in a look-up table at the mapped chromaticity, or by calculating a relative to white luminance, or a luminance decrease, etc.
Claims18
A color mapping method of mapping an input image signal into an output image signal for a display comprising display pixels having three or more sub-pixels with primary colors defining a display color gamut, the method comprises:
- using desirable luminances of reflective spectra of real world objects having different colors corresponding to different chromaticities within the display color gamut, wherein the reflective spectra are spectra of light reflected by respective ones of the real world objects, and wherein a desirable luminance is a total amount of light reflected by a corresponding one of the real world objects,
- gamut mapping the input image signal having input pixel colors defined by an input luminance and an input chromaticity to obtain a mapped image signal having corresponding mapped pixel colors defined by a mapped luminance and a mapped chromaticity, the input pixel colors lying within an input color gamut different from the display color gamut;
- and
- adapting the mapped luminance by using a factor being dependent on a difference between the desirable luminance and the mapped luminance to obtain an output luminance nearer to the desirable luminance than the mapped luminance, wherein the image output signal is defined by the mapped chromaticity and the output luminance.
A color mapping circuit for mapping an input image signal into an output image signal for a display comprising display pixels having sub-pixels with primary colors defining a display color gamut, the color mapping circuit comprising:
- a desirable luminance unit for generating desirable luminances of reflective spectra of real world objects having different colors corresponding to different chromaticities within the display color gamut, wherein each one of the reflective spectra is a spectrum of light reflected by a real world object, and wherein each one of the desirable luminances is a total amount of light reflected by the corresponding real world object,
- a gamut mapper for gamut mapping the input image signal having input pixel colors defined by an input luminance and an input chromaticity to obtain a mapped image signal having corresponding mapped pixel colors defined by a mapped luminance and a mapped chromaticity, the input pixel colors lying within an input color gamut different than the display color gamut, and
- an adapting circuit for using a factor being dependent on a difference between the desirable luminance and the mapped luminance to obtain an output luminance nearer to the looked-up luminance than the mapped luminance, wherein the image output signal is defined by the mapped chromaticity and the output luminance.
Dependencies are inferred from the claim text.