Hierarchical block truncation coding of digital HDTV images

A source coding technique for compressing HDTV (high-definition television) digital images for B-ISDN (broadband integrated services digital network) visual services is presented. The proposed technique is called hierarchical block truncation coding (HBTC). It is a combination of the block truncation coding (BTC) technique and a quadtree segmentation method. The quadtree segmentation is used to decompose an image into homogeneous regions so that the BTC method can exploit the nonstationarity of the image data. Bit rates around 1.46 b/pixel are achieved with this method. Experimental results for several HDTV images are presented. It is shown that greater image compression can be achieved by using a hierarchical BTC method in conjunction with quadtree segmentation, than by applying BTC to an image with uniform block divisions, since the correlation of uniform areas is exploited. This is especially true for appropriate images such as HDTV with large uniform areas