Efficient encoding of DC coefficients in transform coding of images using JPEG scheme

A minimum edge difference (MED) predictor is proposed to enhance the performance of the basic JPEG (Joint Photographic Experts Group) system. The MED predictor uses the edge difference between adjacent blocks for prediction of the DC coefficient of the current block. Analysis based on a statistical model shows that the proposed predictor can encode the DC coefficients more effectively than the JPEG predictor and the optimal single element 1-D predictor. Computer simulation using real images also shows that, when the proposed MED predictor is used, there is about 5% bit rate reduction over the basic JPEG system