This is really good Dennis, cleaned up my contender for the world's worst purple fringing image superbly and there is a yousendit link for that image coming your way in case you want the test image. This was with an old but good Tamron adaptall 200-500 wide open at 5.6, at 500, with a 1.4x converter, into the sun, on a bright day with every windlet on the lake producing a specular highlight, all of which are purple i.e the worst possible conditions for that lens :-)
With patch 360 on this image I found radius/strength needed to go pretty high at 15 and then the threshold reduced extremely low (5) to get rid of the purple. Leaving just a bit of purple in to test the other controls the edge chroma bias settings didn't do anything except reduce effectiveness for me. The expert options seemed to have no effect. Changing to the slow local average mode (which wasn't particularly slow) with default settings seemed initially to make no difference but switching to this after the other sliders had been set for the fast mode 'almost optimisation' this gave an immediate improvement. The 'ab edge v slum/sat' slider then became the critical control working well at median values and the previously critical 'threshold' which I had to set to extreme low became non-critical and could be set to pretty much anything. So for my use case for usability it really only needed strength plus one other slider in each of the two operational modes - just a different one in each. Rgds, Rob. The image link for anyone that might want an examples is https://www.hightail.com/download/OGhlQk15eFVrWStHR3NUQw - which I hope I typed correctly having cunningly sent the image from different machine. Link should be valid for a week. -----Original Message----- From: Dennis Gnad [mailto:[email protected]] Sent: 19 October 2013 13:11 To: darktable-devel Subject: [darktable-devel] Try my new defringe (LCA removal) module! Hi everyone, I made a new iop module designed for removing fringes that come from longitudinal chromatic aberration. This means CA that is evenly distributed across the picture and not a geometrically centered distortion - so something that can not be solved with lens profiles. Often it is seen as "purple fringing" but can also be red/green. However, the approach works phenomenologically, doing a kind of edge-detection on high-saturated edges (A+B channels in Lab space), similar to what RAW Therapee does, but with some enhancements and options - this should be tuned for LCA however, as TCA can also be removed with auto CA removal ("chromatic abberations") or lens profile based ("lens correction"). I am still not entirely sure about it, as there are still some issues: 1. speed (some things can be optimized, but not sure how much they will help) 2. how effectively it is in reducing LCA and at the same time not modifying other parts of the image So for that I need some of you guys, hope some of you can try it on their pictures *which can not be corrected with lens profiles or auto CA correction*. I know that defringe can also work on "geometrical CA" (TCA), but it should be optimized for LCA, as there is currently no module optimized for that in dt. Please use either of those modules and after that check how to remove the remaining CA/fringes with the defringe module. Here is the branch: https://github.com/bluesceada/darktable/tree/defringe and my pull request: https://github.com/darktable-org/darktable/pull/326 I am interested in possible issues for your picture examples, and some ideas for "sane defaults". If you read the code and have some ideas for improvements directly on that level, that would also help me! Thanks for trying and any useful feedback! Dennis ------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60135031&iu=/4140/ostg.clktrk _______________________________________________ darktable-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/darktable-devel This email is confidential and is intended for the addressee only. If you are not the addressee, please delete the email and do not use it in any way. Please note that any views or opinions presented in this email are solely those of the author and do not necessarily represent those of the company. NHBC reserves the right to monitor all email communications. The recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email. NHBC, the National House-Building Council, is limited by guarantee in England, No 320784. Registered address: NHBC House, Davy Avenue, Knowlhill, Milton Keynes MK5 8FP. NHBC is authorised by the Prudential Regulation Authority and regulated by the Financial Conduct Authority and Prudential Regulation Authority. NHBC Building Control Services Ltd, registered by guarantee in England with Company No. 01952969. Registered address: NHBC House, Davy Avenue, Knowlhill, Milton Keynes MK5 8FP. NHBC Services Ltd registered by guarantee in England, No 03067703. Registered address: NHBC House, Davy Avenue, Knowlhill, Milton Keynes MK5 8FP. If you make a claim under a Buildmark policy your personal details will be stored and processed in accordance with the Data Protection Act. Your personal details may be passed to others involved with your claim such as the original builder, or a consultant or remedial works contractor that we may employ in connection with your claim(s) and matter ancillary to your claim(s). Other than disclosure provided for in this statement, we will not pass any data about you to any other party without your permission unless we are required to do so by law. ------------------------------------------------------------------------------ November Webinars for C, C++, Fortran Developers Accelerate application performance with scalable programming models. Explore techniques for threading, error checking, porting, and tuning. Get the most from the latest Intel processors and coprocessors. See abstracts and register http://pubads.g.doubleclick.net/gampad/clk?id=60136231&iu=/4140/ostg.clktrk _______________________________________________ darktable-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/darktable-devel
