uniform quantization the relationship between mse and q has to be respected for each q in a preferred implementation in order to perform the normalization the u201c spatial video codecs u201d are uniformly quantized with a step u03b4 defined as by combining equation 1 and 2 we obtain that the distortion expressed as the mse is function of q defined by mse u03b4 2 12 f u2032 u2061 q 2 c 1 q c 2 2 12 3 where c 1 controls the minimal and maximal quality and c 2 the variation of the distortion according to q in particular the following values have been chosen c 1 5 and c 2 24 this means that the distortion is doubled for each decrease of 24 of the q parameter the proposed normalization procedure is not exact but as we show in fig5 it is possible to obtain on different input signals a similar distortion for a given quality parameter q and this for different u201c spatial video codecs u201d four transforms are displayed the wavelet 53 wavelet haar dct and dpcm according to a given q parameter they introduce a similar distortion moreover we claim that the error e n in the alignment of the n th u201c spatial video codec u201d is small compared to the predicted distortion d n u0192 u2032 q e n e n lt lt d n 4 we have statistically evaluated equation 4 and the performances of the proposed u201c spatial video codec u201d alignment and we report the results.