Hey, just a quick note about the basecurve: that curve is very early in the processing stack. So if you blow your highlights in this stage, they are gone, before you can do something about it. If there are exposure problems it is far better to use the contrast curve in the colour tab, because that is applied later. Cheers Michael
Am 4. Februar 2017 08:55:49 MEZ schrieb "Remco Viëtor" <remco.vie...@wanadoo.fr>: >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 ____________________________________________________________________________ darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
