aliased interpolation of Curves with visible 'jumps' in brightness

[jeffbottom]

I have an adjustments layer on which I am animating a Curves effect. At couple of points during the interpolation between keyframes the image noticeably jumps in brightness. On closer inspection this correlates perfectly with the curves graph in the effects control panel changing. These are very long slow interpolations and mostly it is perfect but at a couple of points the jump is quite visible. It is as though the effect is 8bit at a couple of moments, but it isn't, well, isn't meant to be and usually isn't. The project is 16bit, the footage being graded is ProRes4444, there are no other effects or blessing modes involved and no other layers. odd. it just feels like a numerical precision error.

anyone have any ideas where the aliasing might be coming coming from or how I might workaround the problem to get a smooth interpolation ?

[Mylenium · Accepted solution]

Umm, well:

I am animating a Curves effect.

Sorry, but that's a rather nonsense workflow. It's inherent in how the effect works that you may see shifts with the input curve vs the output curves due to a) the usual limitations of any spline curves with possible overshoot and clipping which you never get to see even if you make the panel full-screen size, b) animating it in the first place. It is simply unsuitable. Use Levels or any more advanced correction effect.

Mylenium

[jeffbottom]

really ? I always assumed the underlying maths would be fine at 16 bit. and how is curves any different to Levels with regard to interpolation, isn't Levels basically a simpler UI of the same transform as Curves with only 3 points ? That said Curves has always —

me as an effect as you have so little access to the controls via scripting.

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