On 12/12/2016 19:40, Ingo Liebhardt wrote: > Hi all, > > Maybe you still remember that I tried an alternative approach to > X-Trans demosaicking (using guided filtering) in March / April this year… > In the end, I was not satisfied, and I gave up on that approach. The > problems were comparable to the Markesteijn algorithm, and the > improvements marginal. > > After giving up on that approach, I was again browsing conference > papers trying to get some inspiration. > I came across the work of E. Dubois, which looked promising. > It is promising, not so much when applied alone, but very much so when > combined with a gradient based approach like Markesteijn. > > I like Jo’s xtrans fringes profile a lot, but the colors get somewhat > muted, overall. > > Contrary to my first approach, this one finally seems to give > reasonable results. > I managed to get good output for the redline bug #10333. > You can have a look here: dropbox link > <https://www.dropbox.com/sh/un1y11uimbqxjjk/AAD3L-Rs9-ztwyBIm4rnCzK-a?dl=0> > This is the output just with demosaic + base curve, nothing else. > > If you want to try some nasty X-Trans images yourself, I made a little > proof-of-concept. > This in form of a fork of darktable, which you can find > here: https://github.com/ILiebhardt/darktable.git > For trying, just compile, deactivate openCL (only C code thus far), > and choose ‚1 pass Markesteijn‘ as demosaicking method (doesn’t work > for 3-pass, and wouldn’t really yield advantages, either). > > Have fun trying, and let me know if you think that this one’s worth > pursuing further (only quick hack so far, and the used correlation > filters are a slow, naive implementation O(m n p q)). > > If you’d like to read some basics concerning the idea, I made a > mini-blog here: http://xtransdemosaicking.blogspot.nl > > Cheers, > Ingo > > > P.S.: concerning my previous approach, J Liles spotted single > pixel artifacts. I found out that these are not related tot the > demosaicking as such. X-Trans 2 and X-Trans 3 have hybrid AF, and the > pixels used for phase detection show higher noise. These are all green > pixels of a 4-group of pixels; never a red or blue, and never a > solitary green. But solving this would be a whole different project... > > > Sorry, it took me a while to give it a test…
I gave it a try with Francisco's last file from issue #10333. Moire is still there, although much less (I don't know if this is supposed to remove them). And colors seem a bit off when using your demosaicing algorithm (the man in the picture is yellowish). Maybe there is something wrong with my test setup, but I followed your instructions (1 pass, no opencl, compiled straight from your github repo). Please tell me if I can provide any information. Regards ___________________________________________________________________________ darktable developer mailing list to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org
