Vector quantization of images using input-dependent weighted square error distortion

The input-dependent weighted-square-error (IDWSE) distortion, which is computationally simple, is shown to offer subjectively better decoded images than the mean-square-error (MSE) distortion. In the presence of image activity, better edge representation is achieved for low-bit-rate VQ image coding without sacrificing anything. This strategy produces an optimal codebook in the IDWSE sense and is therefore preferable to the equivalent subcodebook method. A simple way to compute the image activity is proposed and shown to be quite effective. Introducing block boundary sensitivity in IDWSE distortion produces a decoded image with less blockiness and better edge representation, while the encoder computation is marginally raised