Patent ID: 7009733

Claim:
A method of providing a tone reproduction curve relating to a first image, the tone reproduction curve defined by at least three points selected from the group consisting of an original minimum color value, an original maximum color value, and a user specified control point (USCP) that represents a change in color value from an original color value in an image to a desired color value, the method comprising: defining at least one threshold color value, the threshold color value defining a threshold color value in relationship to at least one of the original minimum color value or the original maximum color value, the threshold color value defining a threshold where if the USCP lies either between an original minimum color value and a minimum threshold color value defined in relationship therewith or between an original maximum color value and a maximum threshold color value defined in relationship therewith, the original minimum or maximum color value associated with that threshold is conceptually moved farther from the position of that original minimum or maximum color value to form a conceptual minimum color value or conceptual maximum color value, and then creating a monotonic tone reproduction curve through: a) the conceptual minimum color value or conceptual maximum color value, b) the USCP, and c) the original minimum color value or original maximum color value that was not associated with the threshold.