Abstract: To be efficient most of the multimedia data are stored and transferred in their compressed format. However, multimedia applications also require flexible processing of the dare to make full use of them. The traditional methods treat compression and processing separately. As for compressed data, it must be decompressed firstly, which is very ineffective to the overall performance of the multimedia applications. So the compressed-domain processing techniques of multimedia data are addressed to improve the situation. The compressed-domain image processing techniques are discussed in details. Some current problems and important future directions are also presented.