Quote:
Originally Posted by madshi
I think the math would either work out the same, or if it does not, YCbCr might be better than RGB. Just a guess, though.
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Since NNEDI3 is nonlinear the math doesn't exactly work out to be the same. I think all other algorithms in MadVR (except spline) are linear so in those cases it doesn't really matter which colour space you use (unless you change the gamma).
Quote:
Originally Posted by madshi
Hmmmm... I'm not sure what you mean exactly with this. The pre-resize shader should already run in RGB. All of madVR's custom pixel shaders (both pre-resize and post-resize) are always fed with RGB data. So why would you convert to RGB, if the data is already RGB? Can you list the exact processing chain for both of these images?
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I fear I've been slightly unclear. This is happened when I put an empty file called YCbCr in the MadVR folder, and used NNEDI3 for luma doubling and Jinc3AR for image upscaling. It seems that MadVR skips the YCbCr -> RGB conversion but doesn't skip the RGB -> YCbCr conversion after the pre-resize pixel shaders. Which means that it's performing NNEDI3 on the wrong colour space which lowers the picture quality.
It seems that this is also the reason I thought NEDI looked superior, and it may be the reason that improving chroma upscaling seemed to slightly improve the luma upscaling in some of those images.