Hi Ingo, Interesting to hear about the speed. That sounds promising. Here my not-that-spectacular laptop is running darktable's Markesteijn 1-pass/3-pass demosaic in approx. 1.4sec./3.8sec. respectively on the CPU for 16 MP images. But there's no reason to worry about optimization this early on. The code only got that fast after it was heavily worked over by Ingo Weyrich from the RawTherapee project. Ulrich Pegelow's recent OpenCL implementation of Markesteijn is now making a significant difference for those with the hardware.
It strikes me that there are very few people out there with the mathematical knowledge and focus to craft a new demosaicing algorithm for a novel sensor. Well worth pursuing if you're one who can do this. The ideal algorithm would be succinct and clear, of course, but is that possible? If you're interested in darktable users testing it, one approach would be to make a branch off of darktable master and add your work as an alternative demosaic algorithm? This would give people in the dt community an easy route to test it. Though it could also build expectations for what is already only "experimental" x-trans support in dt. As you write, despite the debatable virtues of x-trans, the cameras are fine enough that it has become worth the work to deal with the sensors. But so much knowledge and effort has gone into demosaicing Bayer sensors that is hard to imagine that comparably fast and good algorithms for x-trans anytime soon. It is striking to read the original patent application for the Bayer sensor (https://www.google.com/patents/US3971065) and see how it was envisioned to allow usable results from my very simple processing. X-Trans seems much more a fly-by-wire version of a sensor, requiring all sorts of intervention to produce decent output... Dan On Sun, Feb 14, 2016, at 01:04 PM, Ingo Liebhardt wrote: > Hi Dan, > > To come back briefly on the profiling. > > After two passes there are indeed no further visible improvements in image > quality. > > With two passes and some more minor tweaking I’m now at 7.6 seconds with my > not too spectacular laptop hardware. > > I also tried DCI for red and blue reconstruction once the green is there, but > it didn’t look good at all. More false colour artifacts. > > Cheers, > Ingo > > >> Am 08.02.2016 um 23:52 schrieb Dan Torop <d...@pnym.net>: >> >> Hi Ingo, >> >> This is quite interesting work to see... A x-trans demosaic algorithm >> which is well described, high quality, open source, and fast is >> something which I'm sure many people are awaiting. Though of course >> having all of these qualities is a lot to ask! It's great to see >> continued work on this, and in particular addressing the color >> artifacts. >> >> How does the speed of your code when hooked into dcraw compare to 1-pass >> or 3-pass Markesteijn via dcraw? The dt version of Markesteijn is about >> 2-3x faster than dcraw's, if I recall right, but dcraw's Markesteijn >> could still be a good basis of comparison. >> >> How much work would it be to make a CPU variant? So far as I know, all >> of darktable is built to function on CPUs with the possibility of GPU >> speed-up in certain cases. >> >> I can't speak for the dt core developers regarding their interest & >> priorities, of course... >> >> Best, >> Dan >> >> >> >> On Mon, Feb 8, 2016, at 03:42 PM, Ingo Liebhardt wrote: >>> Hi all, >>> >>> Congrats to version 2.0.1. >>> >>> Would you maybe be interested in an alternative approach to the Markesteijn >>> x-trans demosaicing? >>> >>> I see that for Bayer patterns you have a fast one, plus two different >>> high-quality ones (AMaZE and VNG4). >>> >>> The only high-quality one for x-trans seems to be Markesteijn. >>> I personally find that Markesteijn is producing very sharp results, but >>> also quite some false colour artifacts. >>> I’ve been playing around with an alternative approach, and I’m slowly >>> starting to get reasonable results. (even images with lots of green - >>> always problematic - start looking okay(ish)). >>> >>> If you want to have a look: >>> https://github.com/ILiebhardt/xtrans >>> >>> And some sample comparisons to Markesteijn, plus a brief explanation of the >>> idea: >>> https://www.storehouse.co/stories/b8sj2 >>> >>> Don’t be mistaken by my version number: there’s still a lot of work to be >>> done, and I also still have quite some ideas for improvements… >>> >>> So at this stage I just want to carefully pre-inquire if there could be >>> some interest, in principle. >>> >>> Thanks a lot for letting me know. >>> >>> Cheers, >>> Ingo >>> >>> >>> >>> ___________________________________________________________________________ >> 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 ___________________________________________________________________________ darktable developer mailing list to unsubscribe send a mail to darktable-dev+unsubscr...@lists.darktable.org
