| 摘要 |
A video signal is sampled and digitised (42) and wavelet transformed (44). A tree processor (46) extracts from each frame trees of correlated image areas in the sub bands of the transferred image. For the current frame, only those trees (if any) which have changed compared to the previous frame or frames are subsequently encoded. The trees are encoded according to a quantization table selected from a set of such tables. The selection is based on that proportion of the trees in a frame which have changed. The larger the number of changed trees the coarser the quantization. |
