A Table-based Color Matching Approach to Improve Color Calibration for Color Output Devices

Abstract

The color transformation module is important in Color Hard Copy system. The objective of the module is to get the minimum of the color difference between the color signals represented in input devices and output devices. In the proposed method, the color transformation module is implemented in order to reduce the developing time and has the flexibility to modify the module's components. The module performs gamma correction and color matching algorithm whose data is fed and outputted with look-up tables. The table-based color matching approach is to decrease complexity and cost in hardware implementation. In fact, Most of color devices are given linear input signals, but the output color signals are not linear corresponding to the input, even they are centered on some regions within the gamut of the output device. The relationship between the input and output color signals is approximately a gamma curve in the proposed experiments, so the problem can be resolved roughly by the one-dimension gamma correction. The three-dimension color matching algorithm is performed in the uniform color spaces (CIE Lab, CIE Luv) whose color difference is more closely correlated with the perceptual difference. In general, color calibration must be run in such color spaces that the color difference can be quantized to referable values corresponding to the perceptual difference. The Gray Component Replacement theory will be used in processing color separation. The proposed color transformation module can efficiently improve color calibration from the average color difference about 58 down to about 4 for color output devices in the proposed experiments.