| 摘要 |
<p>A companding technique takes advantage of spatial masking in order to avoid problems from noise and/or distortion introduced when storing or transmitting video signals. A forward companding or encoding part of the technique divides a video frame into separate portions. A local average (114) is calculated for each portion. For each pixel or picture element within a portion, the average of that portion is subtracted (118) and the result is subjected to a non-linear forward process (120) which emphasizes those video signals which are close to the local average and which de-emphasizes those video signal portions which are relatively different from the local average. An encoded output is applied to a medium (197) and, upon recovery from the medium, the recovered signal is subjected to a decode process including a non-linear reconstruction process (146) which is the inverse of the non-linear process applied at the encode stage.</p> |
