An easy way to bring down the brightest pixels in a controlled way is to just use the Graduated ND filter setting the blendif parameters in the lightness tab to only hit the brightest pixels. That will let you set exactly the range of brightness you want pulled down and how sharp a transition you want. i.e. it can be done without mucking up the rest of the image.
-----Original Message----- From: Chris Siebenmann [mailto:c...@cs.toronto.edu] Sent: 28 May 2013 22:43 To: darktable-users@lists.sourceforge.net Cc: c...@cs.toronto.edu Subject: [Darktable-users] Best way to recover highlights that are blown in processing? A number of darktable processing steps can push unclipped RAW channels into overexposure under some circumstances (for example, the standard Nikon base curve not infrequently blows highlights out on me). As a relative beginner at darktable, I'm interested in people's views on the best and easiest way to recover the highlights in this case. I think that what I want at a conceptual level is to pull the highlights down (I assume inevitably reducing highlight contrast), but there may be something that gives a better visual look. Things I've tried, without universal success: * the Shadows and Highlights module often doesn't really reduce the blown highlights very much (or at all) and can give me an unnatural look (this may mean that I need to change the 'soften with' setting). * the Zone module also doesn't seem to be able to pull down the brightness of the blown highlights, although it can be used on things that aren't too bright. * Tone curves have defeated my ability to make good fine adjustments at the bright end of the curve without screwing up the rest of the image. I assume it's possible but I'm clearly not doing something right. (I've tried setting the linear preset to freeze most of the 'curve' and then monkey around only with the top end.) (I suspect that this is the right solution and what I want to do is develop some sort of 'highlight recovery' preset, but it's beyond my current darktable skill.) * the Levels module won't let me move the white point out to the right (which I think might have roughly the effect I want but I could be wrong about). Since I suspect that this sort of question always works better with an example, here's a sample D7100 NEF that exhibits the sort of 'blown in processing' effect that I'm talking about: http://www.cs.toronto.edu/~cks/tmp/darktable/DSC_1101.NEF (This picture has some genuinely clipped areas, but only a small number; many more blow out with the default Nikon tone curve.) (Note that I'm presenting this for illustrative purposes; I'm less interested in how to process this specific picture than in how to recover highlights in the general case that this picture is an example of.) Thanks in advance to anyone who has suggestions, guidance, etc. - cks ------------------------------------------------------------------------------ Introducing AppDynamics Lite, a free troubleshooting tool for Java/.NET Get 100% visibility into your production application - at no cost. Code-level diagnostics for performance bottlenecks with <2% overhead Download for free and get started troubleshooting in minutes. http://p.sf.net/sfu/appdyn_d2d_ap1 _______________________________________________ Darktable-users mailing list Darktable-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/darktable-users The content of this email is private and confidential, and unless otherwise stated only the intended recipient may use the content of this email for its intended purpose. 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