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Old 22nd December 2012, 07:09   #16513  |  Link
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Join Date: Apr 2009
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Originally Posted by madshi View Post
Actually, I'm planning to change madVR's defaults to Chroma Catmull-Rom, Image-Up Lanczos3 and Image-Down Catmull-Rom in the next madVR build. All without AR and without linear light, so that even "low-tier" can run smoothly.
I'm not sure about Catmull-Rom for chroma upscaling. In some tests, I can definitely see aliasing introduced with it, even in real-world material. It's also not quite sharp enough to maintain the correct brightness/sharpness for chroma, and still rings quite a bit. I feel like it's an in-between option that has all three of the bad traits; aliasing, ringing, and loss of brightness/saturation to some degree. I would prefer an algorithm that only had two of them.

Bicubic 75 mostly only exhibits ringing. (which almost disappers with the AR filter)

In some ways, I wonder if Mitchell-Netravali might actually be the best choice as a default, even though it's definitely not my preference for chroma upscaling.

The reason being that most people are probably only used to seeing bilinear scaling applied to the image for chroma upscaling. Even Mitchell-Netravali can have more ringing than Bilinear in some cases (but usually not) though Mitchell-Netravali is definitely an improvement over bilinear when it comes to aliasing and sharpness.

Bicubic 75 is the first option where aliasing is mostly not a problem though. I can find examples where there is still aliasing with Mitchell-Netravali or Catmull-Rom, that don't have any (or a minimal amount) with Bicubic 75.

Lanczos 3 (no AR) for the luma upscaling:

At 200%In particular, pay attention to the left of the A.
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