Thank you, it is clear. The thresholds are ging to be very helpful. I'll try out the lockchan=-1 - that's what I had not yet found at the time.
I didn't mean to write that gammac introduced flickering! I hoped to say that gammac, if used right, could be used for DEflickering. I knew I'd read that *somewhere*, but couldn't find it at the time.
I always work scene by scene (I don't need the problems caused by various scene change detectors, and I also like to feed in extra frames at beginning and end of each clip. At the beginning I add the beginning, reversed, and at the end I add the end, also reversed. That often helps the stabiliser and also temporal passes that otherwise sometimes struggle at begin and end of clips.
For gammac, I do use a cleaned and cropped detect clip (I quickly found I had to!), and it works phenomenally well! I'll be using it a lot - initially for all clips, though for quite a few there are other ways I sometimes get better results.
It's all about the right tool for the right problem, and this is a tool I'll enjoy using! There's still a lot of experimenting to do with values for lockchan and lockval. The multipliers for the various colours I'll have to leave well alone as a consequence of colourblindness. Tweaking of colours is possible for me only by working with known grey points. That comes at a later stage, and works pretty well (though I still need someone to tell me if I make mistakes!).
Thank you (and StainlesS) so much for providing it!