Comments on "Interpolative multiresolution coding of advanced television with compatible subchannels" (and reply and additional comments)

Recently, Uz et al. (ibid., vol.1., no.1, p.86-99, 1991) analyzed the propagation of quantization noise in a pyramid (with feedback) and subband decomposition schemes. In this study each band was independently quantized by a scalar quantizer of equal step size. The resulting reconstruction error spectrum indicated that in both the pyramid (without feedback) and subband coding schemes, noise was building up in lower frequencies. The commenters show that a quantizer assignment method, using mean-square-error (MSE) optimal bit allocation, avoids the problem. The authors argue that the problem is more involved than just MSE optimal bit allocation, and that compatible coding was the focus, as well as guaranteed quality, effects of numerical computations, and perceptual effects. The commenters further support their argument.<>