Patent ID: 7545421

Claim:
A method for determining a gamma curve parameter for a gamma curve function for converting a digital signal produced by an optical sensor from a nonstandard color space to a standard color space, the method comprising: (a) capturing a digital reference signal with the optical sensor, the digital reference signal being associated with a reference source; (b) receiving a standardized signal associated with the reference source; (c) deriving a gamma curve compensated signal based on selection of a gamma value and application of a gamma curve function to the digital reference signal; (d) evaluating a joint quality metric representative of the quality of the gamma curve compensated signal, the joint quality metric comprising: a color portion, a noise portion, and a contrast portion, wherein the color portion is based on a relationship within a uniform perceptual color space between the gamma curve compensated signal and the standardized signal, wherein the noise portion is based on a noise level of the gamma curve compensated signal, wherein the contrast portion is based on a contrast of the gamma curve compensated signal, and wherein the contrast portion comprises a luminance contrast portion and a chrominance contrast portion; (e) iteratively repeating (c) and (d) while varying the gamma value so as to minimize the joint quality metric; and (f) selecting the gamma value that minimizes the joint quality metric as the gamma curve parameter.