Digital Image Compression Based on Visual Perception and Scene Properties

Digital compression techniques have made impressive progress in recent years. Frequently, a reader of a paper on compression is left with the impression that one is getting something for nothing; however, compression can only be achieved by leaving out unnecessary information about the image. A compression ratio of 20:1 simply means that 95% of the information in the original image has been eliminated. There are only two types of information that can be removed without seeing degradation in image quality: information that can be accurately predicted or information that the human visual system cannot see. This article will discuss present compression techniques in terms of these two factors and show how even further compression can be obtained by developing a complete understanding of scene properties and those of visual perception. From an analysis based on present knowledge of visual perception and scene statistics, compression ratios in excess of 50:1 should be achievable without perceptible degradation.