Exact DCT-based spatial domain interpolation of blocks in images

In many processing and coding techniques, images are decomposed into blocks of pixels and the DCT is used to transform those blocks. In some situations, blocks are dropped or lost, and, at some point in the processing, they must be restored from their neighborhood in the images. It is shown that an exact interpolation of image blocks can be performed in the spatial domain, using the DCT. The conditions for a solution to exist are derived and the corresponding algorithm requires 8 multiplies per restored pixel. The exact interpolation approach outperforms the alternative methods in the simulations presented, at a significantly smaller computation cost