Daniel, I am not one of the main devs, but I personally would really like to have better possibilities for CA correction overall. You have seen that there is also the "Auto CA correction"? It was ported from rawtherapee [1]. As far as I understood it corrects TCA only, and does so by scaling colors differentially for maximum contrast, kind of doing online-detection and correction -- however it is quite slow, and the lensfun based module is much faster.
What you are suggesting is a way for better profiling data for later use, not online auto-correction, right? So maybe it would make more sense to contact the developers of liblensfun first, and then keep in close contact with darktable as soon as liblensfun has it's first usable implementation, if you want to see it soon in darktable. If you are suggesting a way to generate the profiles from within darktable, that is not really a good idea, as it is only done once for a lens only, and darktable is an editing/processing software. Adding this to darktable would add too much clutter. There are probably several programs [2,3] that can be used for profile generation, I think support for the LCA profile generation should rather be added to that software then. Anyways how you want to proceed, thanks if you will make some improvements on the "opensource-CA-correction front"! - Dennis [1] http://rawtherapee.com [2] http://wilson.homeunix.com/lens_calibration_tutorial/ [3] http://hugin.sourceforge.net/tutorials/calibration/en.shtml Sidenote: What I thought about is also porting the "Defringe" module from rawtherapee [1] to darktable, it offers the options "Radius" (default 2.0) and Threshold (default 25). But I think this is only a "desaturating high contrast edges" module, maybe you want to look at that? If it is what I think it is, this is again a separate thing from LCA, however it could correct some LCA, right? On 31.03.2013 18:34, Daniel J Blueman wrote: > On 31 March 2013 16:48, Daniel J Blueman <[email protected]> wrote: >> In my thesis a while back [1], I developed a strong algorithm and tool >> [2] to automatically generate LCA correction data from an image. These >> correction values hold for the given set of lens parameters usually >> encoded in the image's EXIF fields. >> >> I wanted feedback onsome ideas to bring this tool to a wider audience: >> - reduce runtime/memory usage >> - generating lib lensfun-compatible output >> - ability to work on a directory of images, averaging across related settings >> - moving from python to C/C++ >> >> Finally, I find that LCA correction is depenendent on aperture and >> potentially focus settings (as lens elements are moved); this isn't >> encoded in the existing lensfun correction model [3]. Arguably, having >> a more generalised model which curve-fits these parameters across the >> focal range and perhaps includes error or some sample count will >> provide a more robust solution. >> >> Or, perhaps the tradeoff of being compatible with the existing format >> is sufficient, eg if we add a 'count' field (so we can see where we >> have averaged over fewer lenses). That opens the possibility of users >> being able to submit and access lens profile data in an easier way. >> >> What do you guys think? >> >> Daniel >> >> [1] http://quora.org/thesis-daniel-blueman.pdf >> [2] http://quora.org/ca-correct > > I've just uploaded a new version which just works with the current > opencv version: > > $ sudo apt-get install libopencv-dev pythonopencv > ... > $ ./ca-correct -s uncorrected.png > optimising RG plane... > ... > [ 0.00186529 -0.00299798 0.00015413] > optimising BG plane... > ... > [ 0.00186529 -0.00299798 0.00015413] > > For best results, use minimal processing (eg linear demosaicing) on > raw-converted files; the LCA correction results are good (eg zooming > in to the bottom-right corner): > http://quora.org/lca/uncorrected.jpg > http://quora.org/lca/corrected.jpg > > Over the next days, I'll release a version which shows the lens > parameters and can process a directory of images, giving a lensfun XML > file. > > Thanks, > Daniel > -- > Daniel J Blueman > > ------------------------------------------------------------------------------ > Own the Future-Intel(R) Level Up Game Demo Contest 2013 > Rise to greatness in Intel's independent game demo contest. Compete > for recognition, cash, and the chance to get your game on Steam. > $5K grand prize plus 10 genre and skill prizes. Submit your demo > by 6/6/13. http://altfarm.mediaplex.com/ad/ck/12124-176961-30367-2 > _______________________________________________ > darktable-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/darktable-devel > ------------------------------------------------------------------------------ Own the Future-Intel(R) Level Up Game Demo Contest 2013 Rise to greatness in Intel's independent game demo contest. Compete for recognition, cash, and the chance to get your game on Steam. $5K grand prize plus 10 genre and skill prizes. Submit your demo by 6/6/13. http://altfarm.mediaplex.com/ad/ck/12124-176961-30367-2 _______________________________________________ darktable-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/darktable-devel
