Patent ID: 7916938

Claim:
A computer-implemented method for mapping first image data into a target gamut, the first image data representing an image which comprises one or more colors S each of which satisfies a condition (G1) which is as follows: (G1) S is outside of the target gamut but a color cS is inside the target gamut for at least one positive c, the method comprising one or more computer processors receiving at least part of the first image data from a computer storage and/or a network and executing one or more computer instructions that process the at least part of the first image data to generate second image data, wherein generating the second image data comprises, for each color S satisfying the condition (G1), performing a mapping operation by the one or more computer processors executing the one or more computer instructions, the mapping operation causing the second image data to represent a color S′ to map the color S into the color S′, wherein S ′=α( S ) S +β( S ) W wherein: (i) S′ is in an ε G -neighborhood of the target gamut, i.e. a color (1−ε G )S′ is in the target gamut, where ε G is a predefined non-negative constant independent of S and not exceeding 1/10; (ii) W is a predefined color independent of S, where W is not zero in a linear color coordinate system, and where uW is inside the target gamut for at least one u>0; (iii) α(S) and β(S) are non-negative, and satisfy one or both of conditions (A) and (B), the conditions (A) and (B) being as follows: (A) when k>0 and k→∞, then α(kS)k→0 and β(kS)→β 0 , where β 0 is a positive number independent of S; (B) for all pairs (k 1 ,k 2 ) of positive numbers which satisfy both conditions (B1) and (B2) below, α(•) and β(•) satisfy (B3) and (B4) below, wherein the condition (B1) is specified for a predefined non-negative number ε M independent of S and not exceeding 1/10: (B1) pair (k 1 ,k 2 ) is ε M -ordered, i.e. k 2 >k 1 (1+ε M ); (B2) k 1 S and k 2 S are outside of the target gamut; (B3) β(k 2 S)≧β(k 1 S), and β(k 2 S)>β(k 1 S) for at least one pair (k 1 ,k 2 ) satisfying (B1) and (B2); (B4) α(k 2 S)k 2 ≦α(k 1 S)k 1 , and α(k 2 S)k 2 <α(k 1 S)k 1 for at least one pair (k 1 ,k 2 ) satisfying (B1) and (B2).