1. A non-transitory program storage device, readable by a programmable control device comprising instructions stored thereon for causing the programmable control device to: store image pixel data in a memory, wherein the image pixel data is obtained from an image sensor; transform the image pixel data into a two-dimensional image histogram of values over a color space, wherein the values correspond to a distribution of the image pixel data in the color space, wherein each color in the color space has a noise distribution, and wherein the noise distribution of each color in the color space is x-y separable; create a non-white histogram of values over the color space by identifying non-white pixel values in the image histogram; create a blurred non-white histogram of values over the color space by blurring the non-white histogram; subtract the blurred non-white histogram from the image histogram to create a trimmed histogram of values over the color space; and store the trimmed histogram of values in the memory.