Manipulating Compressed Images1

This paperdescribes anew technique to implementoperations on compresseddig ital video images that allowsmany imagemanipulationoperationsto be performed 50 to 100 times faster than the corresponding algorithms operating on uncom pressed images. This is accomplishedby performingthe operationsdirectly on the compressed data in the DCT domain. In this paper, we show how to transform image spaceoperations into DCT spaceoperations, we describe severalrepresen tative algorithms in the DCT domain and reporttheir performance.