Ah, and by the way @J Liles: could you please explain me a bit more what you mean by ‚textile like artifact‘, I’d like to investigate that one a bit more in-depth. Thx
> Am 21.12.2016 um 20:10 schrieb Ingo Liebhardt <ingo.liebha...@ziggo.nl>: > > Hi all, > > Thanks a lot for the feedback, and no worries if it takes you a while testing > it. > As you see, I’m also progressing rather slowly on my side… > > It’s still a proof-of-concept and I have quite some items on my to do list, > most notably: > - the literature mentions training the filters based on reference images, and > I’m slowly working on this, hoping that it would further increase image > quality. So far, the filters are designed using the window design method. > - trying to find out where the hue shifts come from - I already noticed them, > too. > > Other things like performance improvements will be for later… > > I’ll let you know as soon as I make progress on the filters. > > Cheers, > Ingo > > > >> Am 21.12.2016 um 01:14 schrieb J. Liles <malnour...@gmail.com >> <mailto:malnour...@gmail.com>>: >> >> >> >> On Mon, Dec 19, 2016 at 7:40 PM, J. Liles <malnour...@gmail.com >> <mailto:malnour...@gmail.com>> wrote: >> >> >> On Mon, Dec 12, 2016 at 10:40 AM, Ingo Liebhardt <ingo.liebha...@ziggo.nl >> <mailto:ingo.liebha...@ziggo.nl>> 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 >> <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 >> <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... >> >> >> >> >> >> >> ___________________________________________________________________________ >> darktable developer mailing list to unsubscribe send a mail to >> darktable-dev+unsubscr...@lists.darktable.org >> <mailto:darktable-dev%2bunsubscr...@lists.darktable.org> >> >> Ingo, >> >> Great to hear you're still working on this! >> >> I haven't reviewed the code of the algorithm, but I did give it a try on a >> few images. >> >> Here's one in particular (lots of sharpening added to make the differences >> more obvious.) >> >> http://www.nevermindhim.com/liebhardt-test >> <http://www.nevermindhim.com/liebhardt-test> >> >> Direct image links: >> >> http://www.nevermindhim.com/files/liebhardt-test/6acffe60-09c5-11e6-93d7-178612e3e7eb_E1_VNG.png >> >> <http://www.nevermindhim.com/files/liebhardt-test/6acffe60-09c5-11e6-93d7-178612e3e7eb_E1_VNG.png> >> http://www.nevermindhim.com/files/liebhardt-test/6acffe60-09c5-11e6-93d7-178612e3e7eb_E1_Markesteijn.png >> >> <http://www.nevermindhim.com/files/liebhardt-test/6acffe60-09c5-11e6-93d7-178612e3e7eb_E1_Markesteijn.png> >> http://www.nevermindhim.com/files/liebhardt-test/6acffe60-09c5-11e6-93d7-178612e3e7eb_E1_Liebhardt.png >> >> <http://www.nevermindhim.com/files/liebhardt-test/6acffe60-09c5-11e6-93d7-178612e3e7eb_E1_Liebhardt.png> >> >> >> My first impressions are: >> >> 1) (obviously you know this) It's slow >> 2) It introduces a hue shift >> 3) It does a better job of controlling color noise than VNG or Markesteijn. >> 4) Artifacts are similar in structure to Markesteijn (maze-like) >> 5) There is an additional textile like artifact that Markesteijn doesn't >> exhibit. >> 6) It overshoots in interpolating across gradients, but not as much as VNG >> does. >> >> If you can get rid of the textile effect and, color cast, and speed it up, >> this looks like it would be an improvement over Markesteijn (with no color >> smoothing/noise reduction). It's already looking more "film like" >> >> >> >> Replying to myself here... >> >> Added another set of images to: >> >> http://www.nevermindhim.com/liebhardt-test >> <http://www.nevermindhim.com/liebhardt-test> >> >> (TEST IMAGE 2) >> >> This time correcting for the hue shift (with auto white balance). >> >> I wanted to illustrate how it deals with a high ISO (12800) image, with and >> without noise reduction and sharpening. >> >> As you can see, the result is a definite improvement, especially the noise >> reduced version. There may be a slight loss of sharpness, but for me it's >> worth it to get rid of those crusty false colors. >> >> However, whether or not even this is better than the SOOC JPEG (NR -4, >> Sharpness 0) is debatable. It seems like using the maximum NR in darktable >> is required to produce a similar result as the minimum NR in camera... >> > > > ___________________________________________________________________________ > darktable developer mailing list to unsubscribe send a mail to > darktable-dev+unsubscr...@lists.darktable.org ___________________________________________________________________________ darktable developer mailing list to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org
