Two low cost algorithms for improved diagonal edge detection in JPEG-LS

JPEG-LS is the latest lossless and near lossless image compression standard introduced by the Joint Photographic Experts Group (JPEG) in 1999. In this standard simple localized edge detection techniques are used in order to determine the predictive value of each pixel. These edge detection techniques only detect horizontal and vertical edges and the corresponding predictors have only been optimized for the accurate prediction of pixels in the locality of horizontal and/or vertical edges. As a result JPEG-LS produces large prediction errors in the locality of diagonal edges. We present two low cost algorithms for the detection and prediction of diagonal edge pixels in JPEG-LS. Experimental results show that the proposed schemes aid in the reduction of predictive mean squared error of up to 2-3 percent as compared to the standard.