this implements the popular and simple lift gamma gain scheme to colour grade images.
note that it works in rgb and may result in out of gamut/spectral locus colours.
this is in fact using the ACES colour decision list (CDL) formula for slope/offset/power but i didn't rename the parameters because it's so similar. also this does not work in log space nor in ACEScc colour space, so in a way it's different anyways.
see: ACES S-2016-001 : ACEScct --- A Quasi-Logarithmic Encoding of ACES Data for use within Color Grading Systems
lift hsv colour to lift the blacksgamma hsv colour to push the gamma (affects the mid tones mostly)gain hsv colour gain. this affects the whole image (but mostly pins the highlights) and works as white balance coefficients would.