Abstract: Because of the importance of the discrete cosine transform (DCT) in the field of image processing,various algorithms and architectures for 2-D DCT processor design have been proposed. In this paper, a novel fastcomputing mechanism for 2-D 8×8 DCT and quantization for JPEG or MPEG codec is presented. By an effectivejudging mechanism for an 8×8 image block, the algorithm will adjust DCT computing time depending on thedistribution of an image block. This algorithm costs a few adders, shifters and comparators, but it reducessignificantly the number of DCT computing times which dominates the computing performance of imageprocessing. The simulation result shows that the proposed algorithm could save more DCT calculation thanconventional DCT and integer DCT, and when quantization parameter is large, such as 32, the performance ofproposed algorithm is better than that of small one.