help needed - custom gamma curve?

[zee944]

Hey Everybody,

Can anybody tell me which filter can apply a custom gamma curve to a video? Something like Ylevels() (http://forum.doom9.org/showthread.php?t=79898) does, but with customizable curve, and in the end leaving the black level and the bright parts intact.

Didée's Ylevels() (http://forum.doom9.org/showthread.php?t=79898) uses this gamma curve:

http://img42.exs.cx/img42/7656/gamma_lf.png

Even this curve would do for me, if I could define the range I want to boost up a little. I've played around with Ylevels() but it seems it's not capable to work this way. What I want is to only affect pixels that have luma value between - say - 40 and 200 (so the curve should be shinked to fit between 40 and 200 to avoid clipping). I don't want to touch pixels under and above a certain brightness. Is it possible?

I've even tried to play around with HDR AGC, then modifiing Ylevels() script, but had to realize I don't have the skill for it.

Any help would be appreciated. Whatever you think, please share it. Pretty please! :)

[Didée]

You may want to search up on GiCoCu (by E-Male, located in the "film look" thread).

You're basically asking for arbitrary levels adjustment. While it's perfectly possible to achieve that with MaskTools' Lutxy, in practice it's overly intricate to do it this way.
Better use a dedicated plugin like GiCoCu for that. (Just a pity that PW's storing format isn't supported...)

[zee944]

You may want to search up on GiCoCu (by E-Male, located in the "film look" thread).


Thanks Didée, it seems GiCoCu is indeed what I need!

I have weird effects though when I'm trying to adjust the curve in Gimp (for feeding GiCoCu later). Ylevels processes only luma, and always looks natural, but I'm not sure that Gimp works properly, as it is very, very easy to make the colours false. Perhaps that's the reason you used a fix curve in Ylevels?