PREDICTION ERROR PREPROCESSING FOR COLOR IMAGE COMPRESSION

In this paper, a prediction error preprocessor based on the just noticeable distortion (JND) for the color image compression scheme is presented. The variance of prediction error signals we can reduce, the less objective distortion of the reconstructed image we can achieve at a given bit rate or the lower bit rate of the reconstructed image we can obtain at the same visual quality. Since the human visual perception to color visual signals has a limited sensitivity, any change below the visibility threshold cannot be detected by human eyes. We therefore use a new color JND estimator that is incorporated into the design of the prediction error preprocessor in the color image compression scheme. Without introducing the perceptual distortion into prediction error signals, the dynamic range of prediction error signals for coefficients in each color component of the color image is reduced to increase the compression performance. The estimated JND is also incorporated into the design of the quantization stage in the color image compression scheme. In the simulation results, the bit rate required by the compression scheme with the prediction error preprocessor is lower than that without the prediction error preprocessor at the consistent visual quality of the reconstructed color image.