I am glad the discussion continues, perhaps we will come to good ideas about the color compensation necessary when using the so called linear curve. At this point I would like to make my point again: the linear option in C1 does NOT deliver the raw data from the sensor.
As a first demonstration, we can read again a very good article by Bruce Fraser: http://www.adobe.com/digitalimag/pdfs/linear_gamma.pdf
- You will see that the image corresponding to the raw data is ways darker than the image delivered by the linear curve in C1.
- If you apply to a 'linearized' image in C1 the gamma curve shown on p. 2 in the cited paper, you get a much too bright image.
Second, we can also dive into C1's blog. I recommend the reading of following article: http://blog.phaseone.com/take-full-control-of-the-tone-mapping-by-using-a-linear-film-curve/
. Let me pick a few citations:"By default the curve “Film Standard” is used. This curve is designed to give a similar tone mapping as when using transparency film. The curve has a slight S shape in order to achieve deep blacks while still maintaining details in the highlight, giving a gentle transition into overexposed areas."
This shows that the Film Standard curve is not just arbitrary but... reproduces the limitations of transparency film as well as its brillance. The author adds: "The default ICC Color Profile is designed to work well together with the default curve “Film Standard”".
This is the reason why I would greet the definition of a second ICC profile, which would enhance the results obtained with the linear curve.
In the fourth illustration, we see the curve which must be applied to the linear rendering to obtain the standard rendering. It is an S-shaped curve, very distinct from the gamma curve applied to true sensor data in Fraser's article.
Later on, in the discussion, Niels answers a question: "Yes, you are absolutely right. Gamma correction has been applied. "
So, the sequence seems to be the following:
RAW gamma LINEAR S-shape FILM STANDARD
In C1, linear does not refer to the linearity of the sensor data but to perceptualy equally spaced tone levels of the gamma corrected data, which nowadays cover 12-14 Ev's.
I interpret the Film Standard curve as the expression of the transition between analogue and digital photography, a time in which a good picture is still, for many people, a picture which could have been made with analogue means. In my eyes, the linear curve is as legitimate as a standard as the Film Standard in C1 and should be paired with a specific ICC profile.