I've experimented a bit with ICC profile selection and input tone curves in Capture One, mainly with various Leaf backs.
I've noted that you can change tone curve while the ICC profile remain the same, and there's no strong indication on how you should match them, although it's likely that a "Portrait" ICC should be matched with a "Portrait" curve of course :-), but the naming is not always that way. As tone curves affect color (I'm assuming C1 applies the tone curve in RGB space) this means that color will get distorted if you don't use the tone curve for which the ICC profile was designed.
And yes, I've noted on one test image that when I changed from portrait curve to linear, the shadowy parts of the face got a greenish cast. I traced this cast to the cLUT conversion, and thus got a clear indication that the ICC profile was not designed for a linear curve.
I've search the docs to find a description of how to actually combine ICC profiles and tone curves but failed to do so. Anyone that has any pointer?
I'm specially interested in the linear curves as I want to output for further processing like HDR, but it seems to me that the while many cameras get a "linear" curve as a choice, it's rarely supported by a matching ICC profile, if I've figured this out properly.
well, use simple matrix profiles (w/o LUTs) and linear curve in a proper raw converter... certainly w/o LUTs you might get issues w/ saturated colors