Editing HSL and HSV (section)

===General approach===
HSL, HSV, and related models can be derived via geometric strategies, or can be thought of as specific instances of a "generalized LHS model". The HSL and HSV model-builders took an RGB cube – with constituent amounts of red, green, and blue light in a color denoted {{nobr|1=''R'', ''G'', ''B'' [[∈]] [[Unit interval|[0, 1]]]}}{{refn|group=upper-alpha |In [[#Levkowitz|Levkowitz and Herman's]] formulation, ''R'', ''G'', and ''B'' stand for the voltages on the guns of a CRT display, which might have different maxima, and so their cartesian [[gamut]] could be a box of any unequal dimensions. Other definitions commonly use integer values in the range {{nobr|[0, 255]}}, storing the value for each component in one [[byte]]. We define the RGB gamut to be a [[unit cube]] for convenience because it simplifies and clarifies the math. Also, in general, HSL and HSV are today computed directly from [[gamma correction|gamma-corrected]] {{nobr|''{{prime|R}}''}}, {{nobr|''{{prime|G}}''}}, and {{nobr|''{{prime|B}}''}} – for instance in [[sRGB]] space – but, when the models were developed, might have been transformations of a linear RGB space. Early authors don't address gamma correction at all, except [[Alvy Ray Smith]]<ref name=Smith>[[#Smith|Smith (1978)]]</ref> who clearly states that "We shall assume that an RGB monitor is a linear device", and thus designed HSV using linear RGB. We will drop the primes, and the labels ''R'', ''G'', and ''B'' should be taken to stand for the three attributes of the origin RGB space, whether or not it is gamma corrected.}} – and tilted it on its corner, so that black rested at the origin with white directly above it along the vertical axis, then measured the hue of the colors in the cube by their angle around that axis, starting with red at 0°. Then they came up with a characterization of brightness/value/lightness, and defined saturation to range from 0 along the axis to 1 at the most colorful point for each pair of other parameters.<ref name=Levkowitz/><ref name=Smith/><ref name=Joblove/>