Raw Histogram, or Display Histogram

[ggbutcher (Glenn Butcher)]

@houz

So you don’t have one universal working color space, but you edit in camera RGB? That makes it hard to do the same edits to images taken with different cameras, and might even give other problems, depending on the specific color space. I’d reconsider that and move from camera RGB to somethign like Rec2020 as Elle suggested.

What I wanted i my initial try at CMS was to use the dcraw output colorspace (-o n) as my working space. Thing is, libraw doesn’t make the dcraw ICC until time to save as TIFF, or so it appears, as I can’t find it in any of the data structures available after dcraw_process. So, my first attempt was to use LCMS to build internal profiles for each of the -o options, and assign them to the libraw image for subsequent processing. Actually, that seemed to work quite well, although I can’t really know for sure until I acquire the resources to calibrate my displays. The only thing vexing was when I went to save a TIFF with the working space profile, when I opened it the histogram was different than when output, but the image seemed identical. That’s when I started this thread…

I got back to goodness by abandoning my internal profiles and just using @Elle’s profiles. But, simply assigning her LargeRGB g1.8 to the dcraw -o 4 output just didn’t seem proper, so I’m going to make the following modifications before releasing 0.6:

1. input.raw.cms.rawprofile - name of a .icc to assign to the input image in place of any previously delivered profile This would be intended to be a camera profile, but could be a .icc equivalent for any dcraw-produced profile.

2. Implement a Convert Colorspace tool. As I described above, rawproc is a ‘chain’ editor, the GUI approximation of gmic or imagemagick. I’ll just implement a tool that can be added at any point to convert from the assigned colorspace to one in a supplied file. That’ll be the first tool applied in a workflow that starts with a camera profile-assigned image, to convert to a working colorspace for the subsequent tools.

I debated doing the working space conversion as part of opening the file, but doing it as a tool provides flexibility to apply color space transformations anywhere in the tool chain. Not sure for what, just seems useful, to bear-of-little-brain here…

I want to thank all who’ve responded here; your words have been extremely helpful in schooling me through another part of color management. I’m starting to get the mechanics; will need another couple hundred cups of coffee for the theory.//