Help understanding color profiles

I’ve been using Darktable for a couple of months now, but I just recently got a new Fuji X-H1. I read up about using the x-trans sensor and started taking some test shots. I ran into an issue where the colors were giving me a lot of trouble.

Here is the OOC JPEG. Lowlight shot, handheld

Next is my first edit, using the standard color matrix profile. Exposure and contrast are lower, but notice his white fur. It’s green on one side and purple on the other.


DSCF4454.RAF.xmp (15.3 KB)

Searching here I found a thread that mentioned using Rec709, but not why. After some experimentation with input profiles I got my second edit using the “linear Rec2020 RGB” profile.


DSCF4454_03.RAF.xmp (13.2 KB)

This edit seems much better to me, but I’m not sure when I should use which profile. Should I always use Rec2020?

Finally the raw file:
DSCF4454.RAF (22.5 MB)

This file is licensed Creative Commons, By-Attribution, Share-Alike.

1 Like

Hello @scrawfor, and welcome!

First: I usually say that there are about half a million ways to develop a photo.
Which one is right? Answer: the one you like.

Here is my interpretation:

Color profiles are a real jungle and/or quagmire.

You have a good camera. It delivers RAW files as well as good JPGs, when called for.
Normally, darktable’s input color profile is set to standard color matrix, and working profile is set to linear Rec 2020 RGB, while the output color profile is set to sRGB (web safe) — unless you aim for another output target, of course!

In case you really want to dig down into color profiles, here is a good link:
https://ninedegreesbelow.com/photography/lcms-make-icc-profiles.html

Have fun!
Claes in Lund, Sweden

Thank you @Claes! Ill give that document a read when my mind is fresher! Like the edit!

1 Like

DSCF4454.RAF.xmp (37.5 KB)

Yes, @claes nailed it, color profiles in raw processing are easy to understand. You typically have three in the chain, with two actual transforms because one is used as the input and the other the output for the transform. It works basically like this:

camera (or input) -> working -> display/output

The camera (or input) profile is specific to your camera, and describes the so-called “camera colors”. The first transform is usually to a working profile like Rec2020, and that transform uses the camera profile for the input condition and the working profile as the output condition. The image is then worked in the working colorspace, and then transformed to a display profile for displaying the image (that is, if you have a display profile) or file output (usually sRGB as a least common denominator for whatever display the file ends up on).

It’s really that simple…

Addendum: https://www.richardlackey.com/choosing-video-color-space/

I’m not trying to add to what’s already been said about the profiles. @Claes and @ggbutcher said what needs to be said.

About the image you posted: It does seem to me that the cat needs to be slightly green on his left side (camera right). There’s a rather strong light source in the upper right corner that bounces of the green table/stand/whatchamacallit onto the cat.

I cannot see what light source is on the left and which might cause the blueish light (TV maybe?).

Here’s an edit without any color corrections/manipulations and the default input/output profiles:


color.profiles.raf.xmp (9.8 KB)

2 Likes

I was thinking the same thing.

The correct profile is always the standard color matrix

As a first thing i would try the color zone module

Lower blue saturation
DSCF4454.RAF.xmp (12.0 KB)

@Jade_NL @age
After looking again I think you both are right about the light. Whatever Film Simulation was active in the camera must have just taken out most of those colors, but it does make sense that they were in the frame. And it was a TV providing the blue light.

Good call. I was able something closer to what I envisioned on the standard matrix by de-saturating the yellows & greens and shifting the hues a bit.

Thank you all for your help!

When using rec 2020 as input you are basically saying my camera space is the same as rec 2020. Pending the camera this could be quite close or quite far from the truth. The farther from the truth the more you will get unnatural colours, but as colour spaces of all kinds tend to have somewhat similar shapes, the result usually won’t be a disaster, and in some cases might be more pleasing. Pleasing the keyword there, not accurate. What’s accurate is not always most pleasing! So if you like the look rec 2020 as input creates, use it! If you want accuracy, stick with standard matrix. Like others have said, the white fur of the cat was probably reflecting the strong coloured lights surrounding.