Patent ID: 8478059

Claim:
A method of downsizing a compressed image in the discrete cosine transform (DCT) domain by an arbitrary scaling ratio L/M, where L is a target number of blocks and M is an original number of blocks, the method comprising: performing a non-uniform sampling of DCT coefficients of successive blocks in the compressed image, each block having a DCT block length, by sampling P blocks at a first inverse discrete cosine transform (IDCT) length |P| and sampling Q blocks at a second IDCT length |Q|; where |P| and |Q| are integer functions of the DCT block length and the arbitrary scaling ratio L/M, and where first scaling parameter P is a difference between a product of the DCT block length and L and a product of |Q| and M, and second scaling parameter Q is a difference between M and P; performing a |P|-point IDCT on P blocks, and performing a |Q|-point IDCT on Q blocks, to provide non-uniformly sampled pixel domain samples; concatenating the non-uniformly sampled pixel domain samples into blocks; and performing a DCT operation on each of the concatenated blocks.