Dual Resolution Adaptive DPCM
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-09
A high compression differential pulse code modulation (DPCM)-like coding technique for lossy gray-scale image compression is described below. A variable number of bits along with adaptive quantization are used to code each pixel (picture element) according to the smoothness of the local area of the pixel. The smoothness is determined by a function of the already coded history. This function is referred to as the "smoothness indicator". The scheme achieves an encoding rate of less than 1 bit/pixel by occasionally shifting to a "low resolution" coding mode. It operates best when a very high compression of slightly oversampled images is desired.