White features in clip create green shadows? [SOLVED]

[chewybacca]

Hey guys, still a noob trying to learn avisynth while restoring my uncles VHS tapes as a favor, and wondered if I could get some help with this clip. There's a constant green shadow on all white items in the picture throughout the entire clip. Tried playing with some chroma shifters but I think I'm in over my head again. Any ideas out there?

[manono]

This is a tough one and I have similar problems myself, sometimes. If the green were of uniform strength throughout, it would be much easier. But it's stronger in some places than in others. Here's a start, and I'm hoping others better at this than I will chime in, because this sort of thing is common with VHS captures:

A=Last
B=A.Greyscale()
Overlay(B,A,X=-4,Mode="Chroma")#to realign the chroma (partly)
AddBorders(6,5,0,0)#to make it possible to convert to YV12
ConvertToYV12()
SmoothTweak(Hue2=10)#part of the SmoothAdjust filter - to remove much of the green
Tweak(sat=0.20, starthue=180, endhue=300) #to desaturate the greenish-whitish parts
Crop(8,0,0,-14)#to remove extraneous stuff

[sanlyn]

good work, manono, that grayscale line is intriguing (I must learn about masking and overlays, etc, it's driving me bonkers!).

Might be helpful to note what a histogram shows in YUV. If you convert the source to RGB Rec601 and view an RGB histogram, all colors and luma are blown away at the bright end, against the right-hand side of a histogram. Green is the worst, it's crushed at RGB 255 and climbs up the histogram wall (green arrow in images below). But I don't know how to control Green by itself in YUV.

Source histogram (RGB)

[Attachment 13824 - Click to enlarge]

Source waveform (RGB)

[Attachment 13825 - Click to enlarge]

[chewybacca]

I definitely see an improvement with your script, but I can't seem to make it look much better tweaking the settings. I seem to start pushing reds everywhere the more I try. Here's an actual clip if it helps.

http://youtu.be/-YRCfld6uhA

[chewybacca]

Ok, after much frustration, and a whole lot of avisynth filters, I ended up trying to use Adobe Premiere. After playing around with a couple of Change To Color effects, and an RGB Color Corrector, I think I have the video where I like it. At least the best I can do myself without editing frame by frame to remove the green globs. I'm sure I can do better if I added more specific change to color filters, but I'm out of time on this one.

[sanlyn]

Looks pretty good, why not go with it? Red is over-saturated, but Adobe can fix that, too.