Keep Y only

[Mounir]

So i have this video which is 99% black & white, only a handful frames are in color. The thing is it's from a EP vhs tape the cb and cr components are very (i mean VERY) poluted so the idea would be to keep the Y channel only (not using the cr cb at all) , the luma component is also poluted but to a lesser extent.


I was thinking of grayscaling it maybe but i think it involve using the cb & cr components (?!) which is a " no no".

[Gavino]

Greyscale() will do what you want.
For a YUV clip, it simply sets U and V to 128 (grey) and retains the original Y.

[Chikuzen]

GrayScale() only change all Cb/Cr values to 128.
If you want to remove all Cb/Cr, you should use avisynth2.60alpha and do ConvertToY8().

However, there might not be significant difference because most encoders will convert Y8 into YUV420.

EDIT:
oops, Gavino is fast...

[Mounir]

Thanks for the info Chikuzen here is the result http://img577.imageshack.us/img577/4403/resultt.jpg

Any idea of how to clean the luma now, i have tried fft3dgpu in plane 0 (luma), tried various combinations of sigmas 2,3,4 but it's not that good