This filter suggest a future evolution in two ways :
The non-linear transformation is utilized in some manner to change the contrast of an image.
The idea is to apply this in other spaces to make a avisynth filter i.e. ExpRGB (exp R,exp G,exp B) or to permits more complex operations than the simple exponential.
In reality those transformations are already employeds in professionals products or in paint programs; the fun will be to implements it in open-programs like AviSynth.
If it's true for color filters, it's more true for the area-selection methods; who don't have tried the potentiality of this instrument in commercial graphics programs?
My modest filter show a simple hue selective masking: imagine a meta-filter who apply his transformation in an area defined by a it's own language ..
(sql like example)
select areas where (hue>10) and (luma<8) and (rgb_dist from selected_color <5) and is in (Rect(10,20,100,100))
Note this is a bit simpler because the selection is independent from adjacent pixels