TWO-DIMENSIONAL IMAGE CODING BY MICRO-ADAPTIVE PICTURE SEQUENCING (MAPS).

Micro-Adaptive Picture Sequencing (MAPS), a computationally-efficient contrast-adaptive variable-resolution digital image coding technique, is described. Both compression and decompression involve only integer operations with no multiplies or explicit divides. The compression step requires less than 20 operations per pixel and the decompression step even fewer. MAPS is based on the combination of a simple vision heuristic and a highly nonlinear spatial encoding. The heuristic asserts that the fine detail in an image is noticed primarily when it is sharply defined in contrast while larger more diffuse features are perceived at much lower contrasts. The coding scheme then exploits the spatial redundancy implied by this heuristic to maintain high resolution where sharp definition exists and to reduce resolution elsewhere. Application of MAPS to several imagery types with compressions extending to below 0. 2 bits per pixel is illustrated.