An efficient compressed-domain-based algorithm that works by combining the IDCT
and pixel-domain averaging into a single compressed domain operation, where a part
of the cost of even this simplified operation can be absorbed into the de-quantization
process. The original image need not be decompressed fully, only to the point of
extracting the transform coefficients. Compressed-domain scaling for all scales
k/8 for 1k8, including , , , , is
provided. By chaining multiple operations, any scale factors of the form k1k2
. . . kl/8l for integers ki's in the range [1,7]
can be achieved.
