I have been using RawTherapee for a little and have a few questions regarding the input profile and its location in the pipeline.
I’ve noticed that the tone curve adds hue shifts to the color data, even after using a camera calibration profile (LRPD2 generated.) As such, I am wondering if I should use the tone curve embedded in the ICC/DCP profile as opposed to the tone curve in the Exposure panel.
My question is: when is the input profile applied to the RAW data? I’ve checked the Toolchain Pipeline (Toolchain Pipeline - RawPedia), but couldn’t find a definitive answer. I suspect it’s after the exposure module, but I could be wrong.
In addition, is the tone curve embedded in a DCP/ICC profile applied at the same time in the pipeline or in a different place?
Thank you advance for your support and if the question has already been asked and answered before, I apologize, as I have not found it in the forum.
I’m not a RawTherapee user, but it definitely happens when the image is converted to the working profile. The input (camera) profile’s tone curve should be “null”, or gamma 1.0, no tone change to the data. And, the working profile should also be linear, so the data out of the input → working profile transform should be linear.
In the ICC workflow, the color and tone operations are performed together sequentially. DCP is a bit different beast, here’s a good read on it:
If I were to guess at a position in the toolchain, it’d be just after demosaic, because transform code probably depends on RGB data. There are too many mosaic patterns to make pre-demosaic conversion practical. The purpose of a working profile is to provide “better-behaved” image data to color and tone operations, so the conversion should be done before all that.
Just to confuse you even more, I personally don’t do any color transform until the image is saved to JPEG, so the entire toolchain is working on camera data (well, less and less camera data as each tool is applied). I wrote my own sofware, and it lets me do that.
Thank you for your kind responses and guidance. Turns out my LRPD2 profile pre-bakes some creative adjustments for the color saturation and hue adjustments. The Adobe Standard profile renders more muted and natural pastel colors for skin tones even with aggressive tone curves in film-like curve mode.