Tone Equalizer proposal

[kofa (István Kovács)]

@MStraeten

unsless someone provides the math for it, automagic won’t happen …

Some maths was proposed in this other topic.

monotonic spline interpolations in Darktable

A lot of great modules in Darktable (tone equalizer, contrast equalizer, color equalizer, did I miss something?) are parametrized by a continuous (possibly periodic) function, specified by a few control points, which are then interpolated. The problem is that the interpolation does not preserve monotonicity. This is familiar to all users, but in case someone has not encountered it, here is an example: [screenshot_2024-08-07-093005] I wonder if it would make sense to replace the interpolation …