IMAGE COMPRESSION WITH VARIABLE BLOCK SIZE SEGMENTATION

High quality variable-rate image compression is achieved by segmenting an image into regions of different sizes, classifying each region into one of several perceptually distinct categories, and using a distinct coding procedure for each category. Segmentation is performed with a quadtree data structure by isolating the perceptually more important areas of the image into small regions and separately identifying larger "random texture" blocks. Since the important regions have been isolated, the remaining parts of the image can be coded at a lower rate than would be otherwise possible. High quality coding results are achieved at rates between 0.35 and 0.7 b/p depending on the nature of the original image, and satisfactory results have been obtained at 0.25 b/p.