QUALITY MEASUREMENT AND USE OF PREPROCESSING IN IMAGE COMPRESSION

Traditional quality measures for image coding, such as the peak signal -to-noise ratio, assume that the preservation of the original image is the desired goal. However, pre-processing images prior to encoding, d esigned to remove noise or unimportant detail, can improve the overall performance of an image coder. Objective image quality metrics obtain ed from the difference between the original and coded images cannot pr operly assess this improved performance. This paper proposes a new met hodology for quality metrics that differentially weighs the changes in the image due to pre-processing and encoding. These new quality measu res establish the value of pre-processing for image coding and quantit atively determine the performance improvement that can be thus achieve d by JPEG and wavelet coders. (C) 1998 Elsevier Science B.V. All right s reserved.