| 摘要 |
<p>A digitised video signal is compressed by a form of run-length coding which provides high definition edges and allows run-lengths to be at any video level. Portions of video at constant level are coded as a run-length code (at times t0, t2, t4) which is an 8 bit number with the most significant bit 1 and the remaining bits denoting the number of pixels in the run (up to t1, t3, etc). A special run-length code, all ones, denotes a run length to the end of the current line. At the end of a run, a pixel mode code (at t1, t3 etc) has most significant bit zero and the remaining bits denoting the number of ensuing pixel codes, such as codes 1 2 3 4 and 5 following t1. The pixel codes are any of the 8 bit numbers. The coded data is decoded by responding to a run-length code to maintain the digital values at the value established by the most recent pixel code for as many pixels as specified by the run-length code. On the other hand, when a pixel mode code is received the specified number of pixels are read out sequentially from the memory storing the compressed data. <IMAGE></p> |
