International Journal of Computer Science Issues

More than a traditional journal...

Image transforms are extensively used in image processing and image analysis. Transform is basically a mathematical tool, which allows us to move from one domain to another domain. Transforms play a significant role in various image processing applications namely image compression, image analysis, and image filtering and image enhancement. Nowadays, almost all digital images are stored in compressed format in order to save the computational cost and memory. To save the memory cost, all the image processing techniques like feature extraction, image indexing and watermarking techniques are applied in the compressed domain itself rather than in spatial domain. In this paper, Discrete Cosine Transform (DCT) compression mechanism is used as excellent energy compaction. The image processing tasks can be reduced by considering the approach described in this paper, which consists of finding relationship between coefficients of a block to all other sub blocks in DCT domain without decompressing it. This paper proposes an algorithm in DCT domain which composed of a block from all its sub-blocks and sub-blocks from its block and produces similar result for both operations thus lowering the complexities of the algorithm.