<title>Blockwise distortion measure in image compression</title>

Abstract

The distortion caused by image compression is typically determined by a pixelwise measure such as mean square error. However, these types of measures do not consider global artifacts, like blockiness or blurring. In the present paper an attempt is made to model the distortion by a blockwise measure. A three-parameter distortion function is proposed that measures how well the average intensity, the contrast, and the spatial structure are preserved in the reconstructed image. The distortion in the spatial structure is described by the response of an edge detection operation. The blockwise measure operates with a scrolling block of 3 by 3 pixels to be able to detect distortion beyond the block boundaries.