The Lab color model is defined by the CIE colorimetry standard as perceptually uniform color space, where each color is represented by three numbers: lightness value (L*) and two chromaticity values (a* and b*). The choice of a* and b* components is based on the theory of color vision that states that two colors cannot be both green and red at the same time, nor blue and yellow at the same time. As a result, a* denotes the red/green value and b* the yellow/blue value. The uniformity of the Lab space allows color differences to be equally weighted throughout its domain. During the merge operation ImageWarp treats each pixel in three input images as L*, a* and b* values of the correspondent pixel of the output image and converts them into the RGB triplets using the color coordinate relationship. The opposite process is performed during the split operation. The processing algorithms are applied to the L component only, leaving the other two components intact.