On vendredi 3 février 2017 22:03:47 CET Anton Aylward wrote: > I have a picture of a white barrel cactus (Cleistocactus icosagonus) which > was taken in strong light, bringing out the white 'leafs'. The > illumination is along one edge, rather like a crescent moon. The crescent > is overblown whenever I convert to JPEG, and I can't figure out how to > manipulate it down without the rest of the image being darkened or > distorted.
First thing to check is whether there's anything left to work with in the highlights: if you toggle the 'raw overexposure indicator' (the small square with the RGB bayer mask under the image') and you see all three channels marked as over-exposed, there's nothing really useful you can do (except retaking the image, not always an option) If that's not the case, and you are working from a RAW file, what you can try is using exposure correction with a luminance mask: - go to the 'exposure' module - set the 'exposure' slider to -1 EV (this will darken your whole image for now) - then, select 'parametric mask' as 'blend mode', and in the 'input' sliders push the left closed triangle all the way to the right. Make sure you are at the tab marked with a 'g' (lowercase g!). To refine your mask, you can play a bit with the positions of the left sliders. But check your image if you do that, I found that in some cases I got ugly artifacts when pushing that too much (same reason why I use -1 EV maximum with this maksing). If you want to visualise the mask, click once on the white square with the black disk on it (bottom right in the module). Also, in the 'highlight reconstruction' module, select 'reconstruct in LCh' as method, that might get you back some detail in the blown parts. But be prepared to always get some darkening in at least part of the image, unless you have a very clear separation between the overblown parts and the rest. You don't normally want too sharp a separation between the parts you correct and the rest, as that can easily give you edges/banding at the separation) Btw, there's no reason to turn off the basecurve at any stage in the processing, only to turn it on again later. Remco ____________________________________________________________________________ darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
