add a srgb range/threshold to various effects

Expected behavior of the wanted feature

Hi, I would like to propose a handy feature to make various effects more tweakable by the user. Effects like glsl shader, lavfi filters, build in effects like saturation/brightness/contrast/gamma etc. I'm often face with this problem that I want to use a effect/filter but not on the entire image but on a specific range, like lows/highs/mids (0-255srgb).
There would need to be a smooth transition (smoothstep) between affected area and non affected, to no get a harsh line.
This would enhance our image quality and would open a door for more creative usage of effects. Add a new dimension of flexibility.

an example of what I'm actually talking about
lavfi denoise:
you don't need to apply the filter to the whole image. 90% of the noise is present in the lows 0-40srgb. Here I simulated this effect in photoshop. A better experience. You get rid of the noise in the lows but keep details in the mids, like the face etc.

normal image

denoised with atadenoise

atadenoise applied only to srgb 0-40

Thank you :)

Alternative behavior of the wanted feature

No response

Log File

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Sample Files

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The issue names GLSL shaders, lavfi filters, and built-in effects but no files, tests, or entry points. Start by identifying the affected effect interfaces and existing range-processing paths, then define the scope and verification criteria for applying a smooth sRGB threshold.