It seemed to me that his tequnique was essentially creating a series of 'luminiosity bands' with the various selections. What I didn't see was any blending or feathering between the apparently sharp edged bands but perhaps there was some overlap between them not apparent to me.
I'm not sure this is necessary, or optimum for dt use, but if you want to recreate this you might want to create a few iop instances each with a luminosity parametric slope where the top edge of the parallelogram corresponds to the luminosity band you want to process. The edge slopes defined by the triangles can then either be left vertical for sharp transitions (this nearly always being a bad choice) or sloped for more gradual or 'feathered' transitions. Having the suggested nine or so luminosity bands is probably complete overkill though, I seldom find I need more than two myself in dt but I don't always limit the mask parameters to just luminosity. Rgds, Rob. -----Original Message----- From: Mueen Nawaz [mailto:[email protected]] Sent: 06 January 2015 19:11 To: [email protected] Subject: Re: [Darktable-users] Luminosity Masks in Darktable? johannes hanika <hanatos@...> writes: > > hi, > On Tue, Jan 6, 2015 at 8:42 PM, Mueen Nawaz <mailinglists <at> > nawaz.org> wrote:Hi, > Has anyone considered adding luminosity masks > > oh i'm glad you asked.. there might be a blog post coming up exactly > about that (translating this word into what it's called in darktable, and we've had this feature for quite some time now. it's called parametric blending). I'm aware of parametric masking (which I assume is the same as parametric blending) - I mentioned it in my post. I was going to express skepticism that one could achieve this result with parametric masks, but now that I read Pat David's article in more detail, I think you may actually be correct. The L mask is just a luminosity layer. So with the parametric mask, if I keep the bottom triangles on the input fixed, but move the left upper triangle all the way to the right, I think I'll get the same effect as his L mask. The D mask is likely the opposite. Instead of moving the left triangle, I should move the right triangle all the way to the left. The M mask is a trickier. In his article, the M mask is the intersection of L and D. I could simply move the two upper triangles to the center. This isn't quite what Pat has in his article, as the his M mask has no pixel more than 50% selected, whereas my approach would have the central tone be fully selected. I could perhaps drop the opacity to 50%. I'm not sure if this will exactly get the same as the M mask, but I could play with it. The remaining layers he had (LL, LLL, DD, DDD, MM, MMM) are not as straightforward to translate to Darktable. For LL and LLL, I suppose I could just move the bottom left triangle further to the right to simulate it. The interpolation in DT is still linear, though - I'm not sure it is in his LL, LLL. I think once I go home and fiddle more I'll see if the linear vs nonlinear interpolation makes a significant enough difference. Perhaps it'll be "good enough" even if we can't exactly duplicate his masks. Mueen ------------------------------------------------------------------------------ Dive into the World of Parallel Programming! The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net _______________________________________________ Darktable-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/darktable-users This email is confidential and is intended for the addressee only. 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