Blender AgX in darktable (proof of concept)

Software darktable
2296

We could do away with the shift ratio altogether, and specify the pivot (shift) in EV. So, you’d set your pivot to -1 EV or +0.33 EV or whatever. I think it’s more natural for photographers.

The limits would simply be the black and white relative exposures.

Changing those currently moves the pivot: if the shift was +0.5, and the white relative exposure was the default +6.5 EV, the pivot was at +3.25 EV. If the white relative exposure is set to 5 EV, the pivot would be moved to 2.5 EV. This would not be the case (unless the pivot us outside the updated range). It would move the pivot x coordinate on the graph, though, but photographically that’s probably the better option.

The downside is a bit more complex UI code (adjusting the limits of the pivot x slider), but I think that’s manageable.

2297

@kofa @ndrw I think going this way or that way is both fine. Sure, EV might be easier to deal with. Is a moving x-axis with an EV range on the slider or a non EV range and a fixed axis the better or the worse, I don’t know.
For me it’s basically looking at the picture, adjusting the module to what I think reflects my intention, and that’s it. But I would always support a decision that makes understanding something easier on the user side (even if I would need to re-adopt on the GUI :wink: ).

2298

I think this sounds sensible. At least to me it sounds logical to reference the pivot to a “part of the image” instead of the outer boundaries of the exposure range.