#### Re: How does Luminance slider in Camera Raw split colors by their hue?

Doug Schafer

On Tue, Jan 26, 2021 at 06:12 AM, Dan Margulis wrote:
Does anybody know how those ranges are calculated?
My thought process (in no way disagrees with Dan).....
Suggest you run your own tests. You won't get the math answer and I doubt Adobe would ever release the info (proprietary), but you will have a mathematical relationship result.

Create a full spectrum rainbow color wheel or similar; or just larger than the range of colors you expect to test...then save/look at several results on the colors of moving 1 slider, a specific amount, and analyze  (i.e. color sample eye dropper the results) and tabulate a chart of the results vs. the changes made; and draw your own conclusions.

I would guess the range is not a specific color number set (RGB or Lab), except to start at the exact Hue, 100% away from the center for some amount, and then  a gradient taper from that color to the next with a specific color number cutoff at an end point where there is no effect on image being adjusted.  I think the result will be of a somewhat flattened "normal curve" with the peak at Hue = 0 (for "red") extending partly to Hue = 60 for yellow and partly to Hue = 240 for blue  (for RGB) with slider effects of no impact before yellow or blue. Where the colors cutoff (i.e. the range you are looking for) will be measurable by the color picker and will probably vary by the amount the slider is moved.

If you do so, most here would appreciate your results summary. Once done for 1 color, I'd likely assume a similar scheme is used for each color....unless visual interpretation is used....like Dan said: a difference of science vs. illogical; thus the "normal curve" may not be symmetrical and could be different for each color.

Doug Schafer

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