Design and analysis of an image resizing filter in the block-DCT domain

Image resizing of a compressed image can be performed in a spatial domain via decompression, resizing, and recompression, which is computationally inefficient. In order to reduce computation amount, efficient resizing approaches in the compressed domain have been developed. In this paper, we propose a novel approach to resize images that are compressed by 8 × 8 block-discrete cosine transform (DCT)-based coding. The proposed image-resizing method is performed in the DCT domain and exploits the multiplication-convolution property of the DCT. Filter characteristics of the proposed image resizing method are analyzed by using a multirate filter bank representation. Since the characteristics of our resizing filters are better than those of others and the proposed image resizing method is computationally efficient, it can be widely used in a transcoder and shows visually fine results.