A system or method of automated image processing that can automatically determine a color and transparency for a pixel with an observed color when given the pixel and a background reference color. A point in a color space can be automatically found by extrapolating in the color space based on two points in the color space that respectively correspond to or that respectively approximate the observed color and the given background reference color. A color for the given pixel that corresponds to or approximates the found point in the color space can also be calculated automatically. Based on the found point and the two points in the color space that respectively correspond to the observed color and the given reference color, a transparency for the pixel can be automatically found.