Determining the RYB complement of a color

Question

I am attempting to get the color harmonies of a color in RYB space. I have successfully implemented RGB harmonies, but cannot get RYB harmonies to work properly. They are off by FAR.

My program gets a HEX/HTML color, converts it to RGB, converts the RGB to RYB, converts the RYB to HSL, and performs the harmony calculations from there by incrementing the hue. I used the formulas on https://www.rapidtables.com/convert/color/rgb-to-hsl.html to convert the RYB to HSL. On that page, it gives the formula to convert RGB to HSL. I just use the RYB values in place of the RGB. Below is the formula I use to convert RGB to RYB:

var r = color[0], g = color[1], b = color[2];

// Remove the whiteness from the color.

var w = Math.min(r, g, b);

r -= w;

g -= w;

b -= w;



var mg = Math.max(r, g, b);



// Get the yellow out of the red+green.

var y = Math.min(r, g);

r -= y;

g -= y;



// If this unfortunate conversion combines blue and green, then cut each in

// half to preserve the value's maximum range.

if (b && g) {

    b /= 2.0;

    g /= 2.0;

}



// Redistribute the remaining green.

y += g;

b += g;



// Normalize to values.

var my = Math.max(r, y, b);

if (my) {

    var n = mg / my;

    r *= n;

    y *= n;

    b *= n;

}



// Add the white back in.

r += w;

y += w;

b += w;



// And return back the ryb typed accordingly.

return [r, y, b];

}

When getting the complementary color of Red in RYB, it should be a green. When getting the complementary color of Red in RGB, it should be cyan. My program gives cyan no matter what. The program should give me this: http://prntscr.com/o16ava Instead, it gives me: http://prntscr.com/o16b08

How are you converting the ryb back to rgb before displaying it? — aptriangle, Jun 13 '19 at 15:58
The thing is that I don't convert the RYB back to RGB. I convert the HSL back to RGB to display it on the screen. My program goes from HEX/HTML code ---> RGB 255 ---> RYB 255 ---> HSL ---> RGB by using https://www.rapidtables.com/convert/color/hsl-to-rgb.html — Hexyl Cinnamal, Jun 13 '19 at 16:02
I use the RYB in place of RGB in these formulas https://www.rapidtables.com/convert/color/rgb-to-hsl.html — Hexyl Cinnamal, Jun 14 '19 at 11:37

score 0 · Accepted Answer · answered Jun 14 '19 at 13:57

0

It's not working correctly because, as you mentioned in your comments, you are treating the ryb as if it was rgb when you convert it to hsl.

When you run the code posted above with the values : red = 255, green = 0, blue = 0

It returns the values : red = 255, yellow = 0, blue = 0

Taking the compliment : red = 0, yellow = 255, blue = 255

If you then pass this into a function designed to convert rgb into hsl, it's going to calculate it as if you were telling it to convert : red = 0, green = 255, blue = 255

Which is cyan.

You need to either convert back from ryb to rgb or get a function that is designed to convert ryb into hsl.

answered Jun 14 '19 at 13:57

aptriangle

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Thank you!! I was wondering if you would possibly know any resources on converting RYB to HSL? – Hexyl Cinnamal Jun 14 '19 at 14:14
I don't know any way to do it directly. I would probably go RYB->RGB->HSL. – aptriangle Jun 16 '19 at 18:10
Yes! So I was reading up a bit more about this and came across https://stackoverflow.com/questions/14095849/calculating-the-analogous-color-with-python/14116553#14116553 which provided me with the formula to go from ryb to rgb. – Hexyl Cinnamal Jun 17 '19 at 05:25

Determining the RYB complement of a color

1 Answers1