| 摘要 |
A method is described of encoding pixel colour values for a digital video image frame in which each different colour within the image is assigned a colour value. A predominant colour is identified for the image frame and, in a first embodiment, each pixel having a colour other than the predominant colour is separately coded as its respective colour value (0010 to 1111), with runs of three or more successive pixels of the predominant colour being run-length encoded. A further code (0000 0011 cccc), similar in arrangement to that indicating a run, is provided to allow a change in the specified predominant colour during the course of a frame. In a further embodiment, runs of all colours are run-length encoded but with a shorter coding scheme for runs of the predominant colour or, in a still further embodiment, a small range of predominant colours. A principle use for these coding schemes is to improve efficiency of coding for certain classes of image material.
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