algorithm - Invert a LUT (lookup table) -

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i writing color management code, , dealing luts (look tables).

i can read color profile lut , convert values... but, how can inverse operation? maybe, there algorithm generate 'inverse' of lut?

if lut given, simplest method find closest entry given color value. can accelerate computation variety of methods; example, can build k-d tree out of lut entries , use eliminate of comparisons exhaustive check require.

however, tend result in "posterized" image, since smooth areas in image shift abruptly 1 entry next. can avoid taking pixels in (quasi-)random order, picking best fit lut, , pushing difference between pixel value , chosen entry onto nearby pixels haven't been chosen.

there variety of ways last, result in dithering effect makes better use (for imaging purposes) of available lut entries simple, per-pixel operation can.


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