Image coding using wavelet transform and human visual system
Il Kyu Eom, Hyung S. Kim, Kyung Sik Son, Yoon-Soo Kim, Jae Ho Kim · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1995
In this paper, we propose a new image compression technique using wavelet transform and human visually estimated noise sensitivities. These consist of frequency, background brightness, and edge height sensitivities. The background brightness sensitivity for each quantizing point is modeled by a quadratic function. The edge sensitivity for each quantizing point is modeled by a non-linear function. The minimum value becomes background brightness sensitivity and edge height sensitivity is multiplied by the frequency sensitivity for determining the quantization step size. Quantization step sizes are calculated by using coefficients of lowest frequency band which are coded losslessly. Therefore, in the proposed method, information to specify quantization step size for higher frequency band, is not needed. The coefficients of high frequency bands are arithmetically coded in horizontal and vertical directions depending on the edge direction. Compared with previous human visual systems based image compression methods, the proposed method shows improved image quality for the same compression ratio with less computational cost.