Image Coding
If dependencies exist over T seconds and there are F frames/seconds (considering PCM digital TV, e.g.), the block to be considered has S = T.F.B.L2 ? 3 x 108 bits !
(T = 5, F = 30, B = 8, L = 512).
Thus joint probability functions will have to be computed with a vector length of 300 million!
As this is impossible, our approaches must be limited to single pixels or small blocks, resulting in over-estimates of H(A).
If the blocks of pixels are chosen so that the sequence entropy estimates converge rapidly to the limit, then block-coding methods may provide results close to the minimum length.
The entropy of most natural scenes; has been estimated to be less than 1 bit/pixel. Compression from 8 bits/pixel to 0.8 bits/pixel may be possible by optimal coding of blocks.