On jeudi 25 janvier 2018 07:23:08 CET Robert Bieber wrote: > I've gotten my hands on a proper color checker recently, and I wanted to > try using it with the color look up table module to correct the colors > in an image. If I'm understanding it correctly though, it seems like > the module is the opposite of what I need for this process? > > If I have it right, you can use the color picker to select colors from > the image to set as a source, but then you have to manually adjust them > to get the target color you want from that source. That seems to the idea behind that LUT module, as I understand it: it should allow you to modify the colours in your image in a more detailed way than just using rgb/hsv sliders would allow.
> Shouldn't it be the > other way around, though? Picking the actual colors captured in the > image as the source, and automatically setting the target value to be > the known color of the chart? That would be the role of /correction profiles/, like you have a correction profile for your screen. And such profiles are usually generated automatically from an image of a color checker card, against the reference values provided with that card. (I suppose you could do this manually through the color LUT module...). Note that such profiles are in principle reusable, /for images taken under the same lighting/ (spectral composition). The difference between a correction profile and the darktable LUT module is that the first gives you the colours as they /should be/ (relative to an external reference), the second gives you the colors (color changes) you /want/ (and not necessarily realistic color). > Am I just fundamentally misunderstanding what this module is for? And > if so is there some other one that could do what I'm looking for? You'll need an external program to create an input profile (like you need an external program to generate a screen or printer profile). But, from what I have found, profiling your camera (what is basically what you describe) isn't really worth the effort, if you haven't calibrated and profiled your screen and printer. Remco ____________________________________________________________________________ darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
