Page "Data compression" Paragraph 65

Today, nearly all commonly used video compression methods ( e. g., those in standards approved by the ITU-T or ISO ) apply a discrete cosine transform ( DCT ) for spatial redundancy reduction.

The DCT that is widely used in this regard was introduced by N. Ahmed, T. Natarajan and K. R. Rao in 1974 ; see Reference 1 in discrete cosine transform.

Other methods, such as fractal compression, matching pursuit and the use of a discrete wavelet transform ( DWT ) have been the subject of some research, but are typically not used in practical products ( except for the use of wavelet coding as still-image coders without motion compensation ).

Interest in fractal compression seems to be waning, due to recent theoretical analysis showing a comparative lack of effectiveness of such methods.