| 摘要 |
To enable a digital composite colour video signal (NTSC or PAL) to be compressed directly, that is without dividing it into its components and compressing the components separately, the digital composite colour video signal is decorrelated, for example by spatial sub-band filtering or discrete cosine transform to form data sets, for example sub-bands, representing dc luminance information, ac luminance information and dc chrominance information. The data sets are then quantised in accordance with respective values such that the amount of quantisation of each of some of the data sets to which the dc luminance information and the dc chrominance information is at least predominantly confined is less than the average of the amounts of quantisation of the remaining data sets. At least some of the quantised data sets are then entropy encoded, e.g. run length or DPCM. <IMAGE> |
