Point-wise extended visual masking for JPEG-2000 image compression

One common visual optimization strategy for image compression is to exploit the visual masking effect where artifacts are locally masked by the image acting as a background signal. In this paper, we present a point-wise extended visual masking approach that nonlinearly maps the wavelet coefficients to a perceptually uniform domain prior to quantization by taking advantages of both self-contrast masking and neighborhood masking effects, thus achieving very good visual quality. It is essentially a coefficient-wise adaptive quantization without any overhead. It allows bitstream scalability, as opposed to many previous works. The proposed scheme has been adopted into the working draft of JPEG-2000 Part II