Image Resolution Scaling with Arbitrary Unequal Ratios in each Direction in the DCT Domain

To meet with the different client end devices and network bandwidth transmission requirements, it is necessary to convert the high definition resolution images and videos to standard definition resolution format. A novel approach to convert image resolution with arbitrary ratios in the DCT (discrete cosine transform) domain is proposed, which exploits the relationship of a block and its subblocks with differing size. It can realize arbitrary unequal ratios in the horizontal and vertical direction, respectively. Unlike the present methods, it does not need upsampling-downsampling process. It can perform downsizing directly to the original data and confirms to the standard decoder. The proposed approach is computationally fast and memory efficient and produces visually better images with higher PSNR compared to the spatial methods