I am new to Darktable. Since I started right away with Darktable 3.2 (still using it), I adopted the scene-referred workflow from the outset. I find this new workflow very appealing conceptually.
So far I have been busy learning to use Darktable by applying it to diverse test images. For some of my images I much prefer the result that I can obtain easily with Darktable and the scene-referred workflow. This seems to be especially true for outdoor images with high contrast, like in a photograph featuring a background of glowing mountain peaks during sunset, where filmic seems to help to preserve color in the highlights without producing a HDR look.
But in other cases I noted that the colors produced by Darktable with the scene-referred workflow look really strange. I know that novice users tend to complain about Darktable not reproducing out-of-camera JPEG colors exactly, and I understand that out-of-camera colors are subjective. But I have the impression that the issue that I observe goes beyond that. Here is an example image that demonstrates the problem. (I hereby release this image into the public domain.)
Here are three renderings of the above image:
- Out of camera JPEG (Olympus “natural” profile):
- Default scene-referred with filmic rgb enabled (the only relevant change I did is adjusting exposure correction):
- Like the above, but with filmic rgb disabled:
I’m actually a bit surprised that the filmic result has rather strong contrast and saturation (isn’t it supposed to be rather neutral by default?), but this is not why I am writing this up.
I am most puzzled by the color of the purple brick with plums in the right bottom corner. Looking at it directly with my own eyes (both in daylight and artificial light) both the plums and their background have a purple color. I know that purple is problematic with digital camera sensors, but the OOC JPEG does preserve more-or-less the natural appearance of the brick. The same is true for the Darktable-produced result when filmic rgb is disabled. When filmic rgb is enabled, however, the background color of the brick goes from purple to pure blue. In reality, the color of the truly blue bricks (like the long one in the bottom center) is clearly different from the purple one. There are other such color changes in this image, but the one of the purple brick is the most striking.
Surely, this must have been discussed before, but I could not find an explaination. On the contrary, I read that filmic rgb is not supposed to do anything to colors, only to luminance.
Would someone be so kind to shed some light on this issue or provide a pointer? Many thanks!