Downsampling versus folding in the DCT domain
Rémy Prost, Chaouki Diab · IEEE Transactions on Signal Processing · 1996
Signals can be split into subbands using ideal bandpass filters in the discrete cosine transform (DCT) domain. We show that decimation by band folding is not equivalent to downsampling but results in two convolution operations that involve both the odd and even samples of the signal.