Am Dienstag, 18. Februar 2014, 12:20:50 schrieb Gert van der Plas - Schrama: > Hi,
Hi. > I've noticed that ppg and amaze demosaic create a kind of structured > patterns. The patterns very pronounced with high iso images ceating color > blotches and denoising profile on color causes unpleasant green spikes in > the image. > > I've coded a simple staggered nearest neighbour interpolation demosaic and > it seems to perform better than dt 1.5.2 I checked out of git. Less > artifacts/patterns, color noice is more fine grained and profiled denoising > works better. Sharpness is of course less but for high iso this is very > reasonable. Here is a dropbox link to a 200% screenshot in my patched > darktable-master. > > https://www.dropbox.com/s/l2vquxfu93cm5xs/Screenshot%20from%202014-02-18%201 > 0%3A04%3A03.png > > > I've noticed there are special demosaic algorithms in literature which no > doubt are sharper and more advanced than my simplistic algorithm. In any > case I wondered if ppg and amaze are less suited for high-iso noise and we > might benefit from dedicated noise-capable demosaic code and would > appreciate a wider range of demosaic code. darktable used to offer a wider variation of demosaicing algorithms. We removed most of them when we rewrote parts of our internal processing pipeline since no one wanted to write the code and maintain more variants. If you are willing to provide code for something nifty we can surely negotiate including it. :) NN interpolation is however not an algorithm I would like to see. It has way too many issues. hanatos, please take over. > Best, > > Gert Tobias
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