A novel efficient histogram extraction scheme for contents based image processing in DCT domain

Due to development of internet network environments and data compression techniques, the size and amount of multimedia data has greatly increased. They are compressed before transmission or storage. Dealing with these compressed data such as video retrieval or indexing requires decompression procedure most of the time. This causes additional computations and increases the processing time. In video retrieval and indexing a histogram is one of the most frequently used tools. Efficiency of extracting such histograms will drop down if decompression gets involved. We propose a novel scheme for extracting histograms from images that are transformed into the compressed domain by 8x8 DCT(Discrete Cosine Transform). In this scheme an averaged version of original image is obtained by a simple linear combination of DCT coefficients with the sets of coefficients we designed.