Aha, interesting, thanks! Would you maybe have the raw file for me, I’d like to check something more in-depth? Is this from my very last commit, or the one from the beginning of January? Thx, Ingo
> Am 07.02.2017 um 02:35 schrieb J. Liles <malnour...@gmail.com>: > > > > On Sun, Feb 5, 2017 at 2:35 AM, Ingo Liebhardt <ingo.liebha...@ziggo.nl > <mailto:ingo.liebha...@ziggo.nl>> wrote: > Hi all, > > Thanks again for the feedback, especially to J Liles, which helped me a lot > to find out some issues concerning the filter design. > In the meanwhile, I managed to get rid of the hue shift and of the textile > artifacts. > > A new commit from today is in the (still very experimental) fork at: > 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). > > Compared to the previous one, the following issues are addressed: > 1. Hue shift / lack of overall saturation > 2. Textile artefact > 3. For speed, I noticed that only six filters are required, exploiting > mathematical dependencies of the conversion matrix. It’s still very slow, but > speed optimization is for later… > > You will also see a commit from earlier in January with some first > improvements in the filters. > Using these earlier filters, it is possible to avoid aliasing in the original > problematic picture completely: > https://www.dropbox.com/s/jtgmvuhtuc8uqth/wide_filters.jpg?dl=0 > <https://www.dropbox.com/s/jtgmvuhtuc8uqth/wide_filters.jpg?dl=0> > > But this comes at the price of very pronounced colour bleeding. > > The latest set of filters, which are trained from a reference image, is a > much better compromise: > https://www.dropbox.com/s/ge98px15qm1zpxm/narrower_filters.jpg?dl=0 > <https://www.dropbox.com/s/ge98px15qm1zpxm/narrower_filters.jpg?dl=0> > Although it has a bit of moiré, it is tolerable, and the colour bleeding is > much less with this latest set of filters. > The latest filter set (the trained one) really gives the best compromise > between colour bleeding / false colour suppression. > It also manages really well my hardest test image, where high frequency > changes in luminance were causing severe problems in chroma: > https://www.dropbox.com/s/pgo2scu7o5243ga/L_best_shot.jpg?dl=0 > <https://www.dropbox.com/s/pgo2scu7o5243ga/L_best_shot.jpg?dl=0> > > To compare this to three pass Markesteijn with five times colour smoothing: > https://www.dropbox.com/s/wkv2xlyh9sgw69x/MS3pass.jpg?dl=0 > <https://www.dropbox.com/s/wkv2xlyh9sgw69x/MS3pass.jpg?dl=0> > > Finally, w.r.t. the high iso test image from J Liles, it looks much better > now, too. To note that the serial number of the dollar note are not deeply > green, but this is a price to pay with this CFA and this approach. > > Have fun trying. Looking forward to your feedback. If you’d like to try the > older (broader) filter set, you can go back to the my commit of early January > in the above mentioned git. > > Cheers, > Ingo > > > >> Am 28.12.2016 um 00:35 schrieb J. Liles <malnour...@gmail.com >> <mailto:malnour...@gmail.com>>: >> >> >> >> On Wed, Dec 21, 2016 at 11:27 AM, J. Liles <malnour...@gmail.com >> <mailto:malnour...@gmail.com>> wrote: >> >> >> On Wed, Dec 21, 2016 at 11:20 AM, J. Liles <malnour...@gmail.com >> <mailto:malnour...@gmail.com>> wrote: >> >> >> On Wed, Dec 21, 2016 at 11:17 AM, Ingo Liebhardt <ingo.liebha...@ziggo.nl >> <mailto:ingo.liebha...@ziggo.nl>> wrote: >> 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 >>> <mailto: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 >>> <mailto:darktable-dev+unsubscr...@lists.darktable.org> >> >> >> In TEST IMAGE 1, look at the blue TV screen behind the subject's head. You >> can see a textile/grid type effect that wasn't really there. This effect >> doesn't appear with VNG or Markesteijn. It looks like the your weightings >> might be off causing the X-Trans pattern to show through when interpolating >> solid colors. >> >> >> Just to add to this, other points of interest in this image for finding >> artifacts are the saturated purple lights in the upper right, and the edges >> of the TV screen and the subject's hair. Of particular interest is the >> serial number on the dollar bill. It should be dark green (the same color as >> the stamp/seal above). Too-aggressive chroma denoising may make it turn >> light gray/green like the rest of the bill. >> >> >> >> Continuing my habit of replying to myself, I was curious how your algorithm >> would handle the dreaded X-Trans II/III "purple flare/grid artifact" problem >> (which, AFAICT, remains an unsolved problem everywhere). The result is >> interesting. Your algorithm completely removes the purple color cast of the >> flare, resulting in, IMHO, a much more pleasing appearance. However, the >> grid aspect remains: >> >> http://www.nevermindhim.com/files/liebhardt-test/a75767d6-cc7c-11e6-95bd-739c86278d6a_E1_Liebhardt.png >> >> <http://www.nevermindhim.com/files/liebhardt-test/a75767d6-cc7c-11e6-95bd-739c86278d6a_E1_Liebhardt.png> >> > > > Ingo, > > The colors are looking better now and indeed the textile artifact appears to > be remedied (and that high ISO example is looking pretty good!). However I'm > seeing what I would consider to be excessive color bleeding/halos. > > Observe this image: > > http://www.nevermindhim.com/files/liebhardt-test/bf2e0f63ffa932e34701b47ed0a5a238_liebhardt2.png > > <http://www.nevermindhim.com/files/liebhardt-test/bf2e0f63ffa932e34701b47ed0a5a238_liebhardt2.png> > > It almost looks like chromatic aberration (but isn't). > > As a control, here's the same image processed with VNG + a bilateral filter > on the chroma channel (not enough to get rid of the moire on the tie > though...) > > http://www.nevermindhim.com/files/liebhardt-test/bf2e0f63ffa932e34701b47ed0a5a238_vngbilateral.png > > <http://www.nevermindhim.com/files/liebhardt-test/bf2e0f63ffa932e34701b47ed0a5a238_vngbilateral.png> > > The problem with the tree branch torture test is that the subject is too > monochrome to show these kinds of issues. > > > > ___________________________________________________________________________ > darktable developer mailing list to unsubscribe send a mail to > darktable-dev+unsubscr...@lists.darktable.org > <mailto:darktable-dev+unsubscr...@lists.darktable.org> ___________________________________________________________________________ darktable developer mailing list to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org
