Patent ID: 7864364

Claim:
A color transformation system comprising: memory which stores, for each of a plurality of color separations in a digital image, a plurality of one-dimensional tone reproduction curves, each of the tone reproduction curves for a respective color separation accounting for non-linear colorant interactions between a primary colorant with which the respective color separation is to be rendered, and at least one secondary colorant with which at least a second of the plurality of color separations is to be rendered, each of the tone reproduction curves for the respective color separation including modified input values corresponding to input values for the respective color separation at a respective single fixed input value of the at least the second color separation, including a first one-dimensional tone reproduction curve for the respective color separation at a first fixed input value of the at least the second color separation and at least a second one-dimensional tone reproduction curve for the respective color separation at a second fixed input value of the at least the second color separation, different in amount from the first fixed input value; a processing component, which, for each pixel of the digital image having a given input value for the respective color separation and a given input value for at least the second color separation: accesses the memory and selects, from the plurality of stored one-dimensional tone reproduction curves for the respective color separation, at least one tone reproduction curve for which the fixed input value for the second color separation is close to the given input value for the second color separation for the pixel; for each of the selected tone reproduction curves, determines a modified input value for the respective color separation which corresponds to the input value for that color separation; and where more than one tone reproduction curve is selected, determines a combined modified input value for the respective color separation of the pixel as a function of the modified input values for the respective separation determined from the selected tone reproduction curves; and outputs the modified input value for the pixel of the digital image, whereby for each pixel of the image having a given input value for the respective color separation and a given input value for at least the second color separation, each selected at least one tone reproduction curve is one for which the fixed input value for the second color separation is close to the given input value for the second color separation.