How does Luminance slider in Camera Raw split colors by their hue? #colortheory #photoshop #lightroom #colors


John
 

Hi,

the HSL panel in Camera Raw allows adjusting Luminance for 8 color ranges I assume.

 

Does anybody know how those ranges are calculated?

 

For ex. what does "Reds" actually mean, how does it determine what is red and not orange for ex.

it's clear that RGB or other color space values are in play here, but how does the math actually work.

For ex rgb(255,0,0) is pure red and rgb(255, 165, 0) is orange

then, a pixel with the color rgb(255,83,0) will be affected by the oranges slider, or the reds slider? and how is that determined, simply by dividing the "difference" between the 2 colors equally?

I know you can also convert rgb to hsl or hsb, is the separation between colors done by dividing the h ranges into 8 equal parts centered on the "pure" colors?

 

Also, I suspect that this uses the CIE LAB color space, but I have no idea how to split the the colors by hue in that colorspace.

 

Take a look at the following image. It marks the areas affected by the Luminance setting of the various sliders (Reds, Oranges, etc). It clearly shows that the ranges differ in size and they even overlap significantly (blues and purples).



any input is welcome!

 

thanks,

 

John

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