Aliasing artifacts of subband coded pictures at low bitrates can be eliminated by adding the information from the higher bands that cancel aliasing at the lower band. This is done by DCT coding the high-frequency bands and selecting the coefficients with the highest energy. The optimum scanning directions of these coefficients for each band are given. As an application of these ideas, a method for the transmission of high-resolution still pictures at 64 kb/s based in a combination of subband analysis/synthesis and a modified H261 video codec is proposed. The progressive buildup obtained with this method is pleasant to the human observer, and is four times faster than if the DCT alone were used.
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