I want to understand how the raw files output from Libraw relate to a camera's radiometric response function.
According to various sources (e.g. https://link.springer.com/referenceworkentry/10.1007/978-0-387-31439-6_5....), a camera's radiometric response function (RRF from here on) is a function that transforms sensor irradiance (sensor irradiance has its own definition) into measured intensities (levels/digital numbers) that are the output from the camera. Are these the values we get from the raw files decoded by Libraw? Or are the values transformed somehow?
From what I've read, the RRF is invertible. Applying the inverse of this function to these digital values gives us the sensor irradiance values (or a linear relationship thereof). I believe this is commonly called "linearization", but I'm not sure. Does Libraw (always) output these kinds of "linearized" RAW files, where the inverse RRF has been applied?
I found some forum posts via Google that may be related. For example, in the following post
there are references to an embedded "tone curve" or "linearization curve". Are these the RRF? Are they the inverse of the RRF? Are they something else?
Sorry if this has already been answered or documented. I found no results for "radiometric response function libraw" on Google.
I suspect the answer may not be so simple.