DCT domain alpha blending

For direct manipulation in the compressed domain, we develop a DCT domain convolution theorem which besides exploiting the sparseness of the DCT domain representation also exploits the orthogonality and symmetry in the DCT domain representation. These properties lead to efficient compressed domain based processing methods unlike their spatial domain counterparts, where such properties are not available. This theorem can be used in a variety of image and video editing functions when the image and video data are available only as a JPEG or MPEG bitstream. We illustrate the use of these DCT domain convolution theorems in a typical video editing application such as video bluescreen editing