Patent ID: 7623266

Claim:
A method for mapping cusp points for use in a gamut mapping process, the method comprising: inputting a source point having a source hue value in a first color gamut; obtaining a source hue wheel and a destination hue wheel, each comprising known hue angles for each of primary and secondary color components of the first color gamut and a second color gamut, respectively; determining a relative position of the source point on the source hue wheel between the primary hue nearest to the source point in the source hue wheel and the secondary hue nearest to the source point in the source hue wheel; determining a first lightness value for the primary hue nearest to the source point in the source hue wheel and a second lightness value for the secondary hue nearest to the source point in the source hue wheel; interpolating, utilizing the relative position of the source point as a factor, between the first lightness value and the second lightness value to obtain a first interpolated source lightness value at the hue value of the source point; determining a first maximum chroma value from the boundary of the first color gamut at the first interpolated source lightness value and the hue value of the source point, wherein the first interpolated source lightness value, the hue value of the source point, and the first maximum chroma value define a source primary cusp point; determining, in the destination hue wheel, a corresponding relative position between a destination primary hue on the destination hue wheel and a destination secondary hue on the destination hue wheel, corresponding, respectively, to the relative position of the source point on the source hue wheel between the primary hue nearest to the source point in the source hue wheel and the secondary hue nearest to the source point in the source hue wheel, the corresponding relative hue position on the destination hue wheel having a destination hue value in the destination hue wheel; determining a first destination lightness value for the destination primary hue and a second destination lightness value for the destination secondary hue; interpolating, utilizing the corresponding relative position as a factor, between the first destination lightness value and the second destination lightness value to obtain a first interpolated destination lightness value at the destination hue value; determining a first maximum destination chroma value from the boundary of the second gamut at the first interpolated destination lightness value and the destination hue value, wherein the first interpolated destination lightness value, the destination hue value, and the first maximum destination chroma value define a destination primary cusp point; mapping the source primary cusp point to the destination primary cusp point using a shear mapping technique, and storing the mapping of the source primary cusp point to the destination primary cusp point in a memory.