The efficiency of perceptual coding in compressing color images relies on the estimation of perceptual redundancy. In this paper, a color image coder is proposed for perceptually lossless image compression which shapes the coding error as a part of perceptual redundancy. The perceptual redundancy inherent in each pixel of a color image is estimated in terms of a triple of values, one for each color channel, as a detection threshold for distortion. Based on the exploitation of the detection threshold, the coder is perceptual tuned to select an appropriate mode for coding each sample in each color component. The detection thresholds are further used in controlling the quantization strategy to make sure that the resulting quantization error is not perceivable. Since the estimation of error visibility thresholds is accomplished by using the reconstructed color pixels and predicted color pixels, it promises that lower bit rate can be achieved without transmitting any side information. Simulation results show that the proposed color image coder removes a larger amount of perceptual redundancy. The bit rate required by the proposed color image coder is less than that required by the JPEGLS for the same subjective visual quality.
['Chun-Hsien Chou', 'Kuo-Cheng Liu', 'Chien-Ming Lei']
Color image compression exploiting visual information