Patent ID: 7995237

Claim:
In a computerized color management system having a user-selectable gamut mapping model, a method for transforming a source device colorant value in a source device colorant space to a corresponding destination device colorant value in a destination device colorant space, wherein the source and destination device colorant values each have non-black colorant values and a black colorant value, and wherein the source and destination device colorant spaces are colorimetrically characterized by source and destination device models, the method comprising: determining, by using a computer, whether all of the non-black colorant values of the source device colorant value are or are not all zero; transforming the source device colorant value to a colorimetric value using the source device model; transforming the colorimetric value to a gamut-mapped colorimetric value using the user-selectable gamut-mapping model; and converting the gamut-mapped colorimetric value to a destination device colorant value, wherein the conversion to the destination device colorant value is based on the determination in the determining step, such that in a first case where all of the non-black colorant values of the source device colorant value are determined to be all zero, the gamut-mapped colorimetric value is converted so that the black colorant value of the destination device colorant value reproduces a lightness of the gamut-mapped colorimetric value relative to a gamut boundary for the destination device model, and so that all of the non-black colorant values of the destination device colorant value are zero, and in a second case where all of the non-black colorant values of the source device colorant value are determined to be not all zero, the gamut-mapped colorimetric value is converted so that a combination of the non-black and black colorant values of the destination device colorant value reproduces the gamut-mapped colorimetric value.