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Old 13th April 2009, 12:06   #219  |  Link
madshi
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Join Date: Sep 2006
Posts: 9,140
Quote:
Originally Posted by FoLLgoTT View Post
I compared the chroma upsampling a bit and I noticed that madVR's frequency response is noticeably lower than ffdshow's (HQ upscaling and Lanczos resize to 1920x1080). In both cases I used Lanczos4 for resizing.
These are pretty interesting tests - thanks! Are these test pattern (legally) available somewhere for download?

Quote:
Originally Posted by FoLLgoTT View Post
If you look at the middle of the Siemens star you'll see that the lines are not fully resolved. Without the resampling option in madVR the resolution stays almost the same, but aliasing occurs.
Which madVR resampling option do you mean?

Quote:
Originally Posted by FoLLgoTT View Post
The problem is even more visible at the burst pattern. The amplitude of the chroma signal begins to fall at 1MHz.

Is this a bug or just a side effect of your upsampling algorithm?
I've optimized my chroma upsampling algorithm in such a way that it gets rid of all the nasty aliasing. That may result in a hit on frequency response. Of course that's not nice. But we have to set our priorities right: Do you want higher frequency response and live with ugly jaggies? Or do you want smooth jaggies and can live with a lower frequency response?

Please check out the chroma upsampling screenshots in the 2nd post of this thread. Don't you agree that madVR's chroma upsampling looks *a lot* better than ffdshow's HQ chroma upsampling in those screenshots? I guess I could offer "nearest neighbor" chroma upsampling. That would probably produce a perfect frequency response. And it would result in the most ugly chroma upsampling quality possible...

But seriously, I could allow different chroma upsampling algorithms (e.g. Bicubic and Lanczos) to be selected in addition to the currently used very soft resampler (which is SoftCubic100). So you could find your own compromise between jaggies and frequency response. Would you consider that useful?

Can you see the "missing" frequency response in any real life pictures?
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