_,,,^..^,,,_ said:
Spaced Ranger, could you elaborate an avisynth script for your method?
I never found an Avisynth plug-in that accepts a paint program's histogram functions numbers. However, in the Song Of The South thread, I noted that VirtualDub with a plug-in (Gradation Curves v.1.46b by BBugBunny, A.K.A. Alexander Nagiller) allows for a manual reconstruction of the histogram graph:
http://originaltrilogy.com/forum/topic.cfm/Song-Of-The-South/post/641915/#TopicPost641915
I know it's cludgy but that's the best I could find.