White Balance in RawTherapee

[ldigirol (Larry DiGirolamo)]

I’m using an X-Rite ColorChecker Classic along with Adobe DNG and DCP applications to make camera profiles for use in RT. I have a repeatable, controlled environment in which I shoot and am interested in consistency rather than artistic expression. Is it better for me to use the colors created by the X-Rite reference DCP and not use the WB tool in RawTherapee?

[Claes]

Hi Larry,

No reply in 22 hours? That is bad!
All right, then I will stick my neck out and say that
you need both!

You stated that you are “interested in consistency” rather than “artistic expression”. (Not sure that those two would contradict each other, but still…)

Could I interpret that as you would like to reach “exactness”? I.e. if the object is of a certain colour (say, RGB xyz), you would like to see RGB xyz on the display as well in a print?

Have fun!
Claes in Lund, Sweden

[paperdigits (Mica)]

I agree with @Claes, you need both, probably. If you can measure and set the white balance in your camera, then you may not need RT’s white balance tool (RT should.find the correct white balance from your file).

[ldigirol (Larry DiGirolamo)]

Thanks Claes and paperdigits!

I’m basically taking measurements with the camera, and want to be sure that my processing is consistent from image to image.

The X-Rite/Adobe camera profile is aimed at a color temperature of 5000K which is fine with me. When applying that profile in RawTherapee I realized that I may not want to use the on board white balance tool because it might undo what my camera profile has done. Before and after images seem to support my theory, but I wanted to ask the user group to confirm my thinking.

Thanks again!

[ggbutcher (Glenn Butcher)]

@ldigirol, sorry for the belated response, but I’ve been messing with just this, using ICC profiles. There was a discussion in another thread recently that cast concern on traditional WB compensation in the context of being just another arbitrary channel modification, where the chromatic relationships are disturbed. E.g., if you aggressively apply a curve, the colors will also change visibly. A white balance multiplier is in that category, and the camera numbers can be especially aggressive.

So I conducted a little experiment with a previously generated camera profile produced on a white-balanced target shot. I re-generated the profile, but this time i used another raw development of the target shot, one that was only demosaiced and not white-balanced. You can regard the effect of the two profiles here, as well as read some of the surrounding discourse:

GIMP 2.10.6 out-of-range RGB values from .CR2 file

Okay, I know this thread is getting entirely too long, but I’ve been picking through this year’s images and re-processing selected ones with the new camera profile I made back in post #102, then comparing them with what I did with the old profile that required separate white balance. The difference is marked; I’m starting with richer colors. Here’s an example, first the old rendering: [DSG_1099] Then, the new rendering with the uwb profile: [DSG_1099_uwb] Now, the first profile might jus…

The color difference is marked.

I’ve re-developed some of my sunlight-based images with this new profile, and the starting saturation is such that it compels me to not have to apply saturation later in the processing. Effectively, the white balance correction takes place in the color conversion from the camera profile to the working profile, as what @gwgill called a ‘chromatic transform’.

Now, this is probably a challenging thing to do with ‘regular’ software, as most desperately want to white balance before demosaic. I use my hack software, which lets me start with the ‘really raw’ bayer mosaic, so I can add operations in any order that suits my fancy. I also don’t have the capability to use DCP profiles, so I can’t speak to whether or how this concept would apply in that workflow.

But yes, my investigation to date would lead me to answer Yes, it would be better to use camera profiles to compensate all camera chromatics, including white balance.

[ldigirol (Larry DiGirolamo)]

Yes! Thanks for that, Glenn.

In my case, the RT white balance tool resulted in a much warmer image than the 5000K camera profile had provided. It seems that RT’s approach to white balance may be a standard processing associated with my Nikon D3100. I’m going to stick with my camera profile and steer clear of the WB tool.

Thanks again

-Larry

[ggbutcher (Glenn Butcher)]

I never could use color temperature/tint in a way that made my images look better. I’ve had better results with per-channel curves, which is really just another way of doing white balance multipliers. But all is subsumed by the camera profile that has WB ‘baked in’…

[afre (Alan)]

This might help: How to create DCP color profiles - RawPedia.

[ldigirol (Larry DiGirolamo)]

Thanks afre. I had read that RawPedia page. It’s actually more detail than I need for my application but I appreciate the guidance!