Patent ID: 7233623

Claim:
A method of calculating a discrete cosine transform (DCT) of blocks of pixels of an image for compressing image data to be stored or transmitted, comprising: a) defining first subdivision blocks as range blocks, having a fractional and scalable size N/2 i *N/2 i , where i is an integer; b) defining second subdivision blocks of N*N pixels as domain blocks, shiftable by intervals of N/2 i pixels; c) ordering the pixels in the range blocks of a certain dimension by rearranging input pixels in 2 i vectors of 2 i components; d) calculating, in parallel, 2 i monodimensional DCTs by processing the vectors defined in step c); e) arranging output sequences of the monodimensional DCTs relative to the 2 i vectors; f) completing the calculation in parallel of 2 i bidimensional DCTs by processing output sequences of monodimensional DCTs produced in step e); and g) arranging output sequences of bidimensional DCTs generated in step f) in 2 i vectors of bidimensional DCT coefficients.