Exposure Module: Tooltip change + Comment overhaul

[anoderay]

While documenting the exposure module's Highlight Preservation Mode I thought about its tooltip. In my opinion the mention of having to use a tonemapper to avoid highlight clipping is not necessary. : Most users are using a tonemapper anyway and at least to me (and this poster) it was more confusing then helping. Also darktable doesn't warn about potential highlight clipping in other modules that might raise highlights (like tone equalizer, exposure module itself etc.).

While I was at it, I noticed the code comment in _get_highlight_bias() was no longer accurate. It listed only Nikon and Fuji. I updated it to point to _check_highlight_preservation() in src/common/exif.cc, where the per-camera detection actually happens.

[MStraeten]

Also darktable doesn't warn about potential highlight clipping in other modules that might raise highlights (like tone equalizer, exposure module itself etc.).

as long as you’re using scene referred modules, those won’t cause clipping. Clipping occurs if you don’t use a tonemapper to bring a large tonal range into a small one. E.g. by using display referred modules simply ignoring everything outside the 0..1 range. As long as you are in scene referred mode, use proper modules abtrage default pixelpipe position and then use a tonemapper, there’s no risk for clipping.

So why darktable should warn you, if you point your gun to your feet and then press the trigger …

[anoderay]

as long as you’re using scene referred modules, those won’t cause clipping.

Exactly my point - we don't need to warn about potential clipping in the exposure module as the tooltip currently does.

[ralfbrown]

I wouldn't call a comment change a code overhaul, but it's appropriate and avoids further divergence between comments and actuality if more model support (e.g. Sony) is added in the future.