1. A method for processing color pixel data of an image, comprising the steps of: computing using bit-shift operations an approximation of at least one of a plurality of other color space components of a pixel represented in RGB color space, wherein the at least one other color space component includes luminance, and an approximation of luminance (Y) is computed by summing a red component (R) of the pixel shifted a first number of bits, a green component (G) of the pixel shifted a second number of bits, and a blue component (B) of the pixel shifted a third number of bits; and evaluating a characteristic of the pixel in response to the computed approximation of the at least one of the plurality of other color space components.