Algoritm for RGB Values for Color Wheel

Ben Rubinstein benr_mc at cogapp.com
Mon Sep 12 16:32:33 EDT 2016


http://www.easyrgb.com/index.php?X=MATH&H=02#text2
followed by
http://www.easyrgb.com/index.php?X=MATH&H=16#text16
?

On 12/09/2016 20:49, Sannyasin Brahmanathaswami wrote:
> @ Scott:
>
> changing constants to
>
> constant color1 = "255,0,0" -- red - primary
>
> constant color2 = "255,64,0" -- red-orange - tertiary
> constant color3 = "255,127,0" -- orange - secondary
> constant color4 = "255,191,0" -- orange-yellow - tertiary
>
> constant color5 = "255,255,0" -- yellow - primary
>
> constant color6 = "191,255,0" -- yellow- green  - tertiary
> constant color7 = "0,255,0" -- green - secondary
> constant color8 = "0,191,255" -- green-blue - tertiary
>
> constant color9 = "0,0,255" -- blue - primary
>
> constant color10 = "127,0,255" -- blue-violet - tertiary
> constant color11 = "127,0,127" -- violet  - secondary
> constant color12 = "191,0,127" -- red-violet- tertiary
>
> We get close to the so-called "official" color wheel. Of course we enter the quicksand territory of subjective choices, CMYK gamut (geared to pigment) vs RGB gamut (light based), using yellow, cyan, magenta as primary apexes instead of RGB 255 on three channels etc.  So the precise logic for setting values starts to blur as we move toward "recognition" colors that people expect.. which are more pigment based.
>
> The algorithm:
>
>  "go up and down by halves" (255, 127, 64)
>
> worked in the yellow to orange-red range, but did not work, or works differently, in the blue to violet-red range.  If we wanted to drop back to the pigment based gamut, then we have to find a way to algorithmically "add mud" to all of them… tricky…
>
> Interesting… at any rate… I got what I needed… a lot easier (an less messy!) than the old days when I had to actually mix inks for the KORD!
>
> BR
>
>
> On 9/12/16, 8:00 AM, "use-livecode on behalf of Sannyasin Brahmanathaswami" <use-livecode-bounces at lists.runrev.com on behalf of brahma at hindu.org> wrote:
>
>     Thanks Scott.. this gets me very close and I can see the pattern.
>
>     I can tweak this to get to the "official" formal color wheel which has the three primaries, three secondaries and six tertiaries in proper order
>
>
>
>
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