Fractional scaling of image and video in DCT domain

An algorithm for scaling image and video with fractional factors of 1.25 and 1.50 directly in compressed (DCT) domain without explicit decompression and recompression is presented. It differs from those compressed-domain sampling methods that work only with integer factors, and provides more flexibility in changing image sizes. We employ a simple, consistent and extensible way to implement the algorithm. The resulting scheme ensures that the compressed domain algorithms always use fewer arithmetic operations than their conventional spatial domain counterparts. Experimental results in terms of visual quality and objective evaluation are provided.