Fast DCT domain filtering using the DCT and the DST

The use of the discrete sine transform (DST), together with the discrete cosine transform (DCT), for processing of compressed digital video and images, is introduced. Using this approach, a method for efficient spatial domain filtering, directly in the DCT domain, is developed and proposed. It is demonstrated that, in typical applications, the proposed algorithm is significantly more efficient than the conventional spatial domain method, and a recently-proposed advanced method. It assumes a separable kernel, but no symmetry is required. The method is applicable to any DCT based data compression standard, such as JPEG, MPEG, and H.261.