Greyscale (clip [, string "matrix"])
Converts the input clip to greyscale (without changing the color format).
In YCbCr based formats, the chroma channels are set to 128. In RGB based formats, the conversion produces the luma using the coefficients given in the matrix parameter (rec601 by default, which reflects the behaviour in old AviSynth versions). This option is added in v2.56. When setting matrix="rec709", the clip is converted to greyscale using Rec.709 coefficients. When setting matrix="Average" the luma is calculated as (R+G+B)/3. See ColorConversions for an explanation of these coefficients.
$Date: 2008/02/10 13:57:17 $