Convert RGB color to CMYK?

Question

I\'m looking for an algorithm to convert an RGB color to CMYK. Photoshop is performing the conversion below:

R = 220 G = 233 B = 174

C = 15 M = 0 Y = 40 K =

Answer 1

For convert RGB to CMYK you can use ColorHelper library.

using ColorHelper;
RGB rgb = new RGB(220, 234, 174);
CMYK cmyk = ColorConverter.RgbToCmyk(rgb);

Conversion algorithm in this library:

public static CMYK RgbToCmyk(RGB rgb)
{
    double modifiedR, modifiedG, modifiedB, c, m, y, k;

    modifiedR = rgb.R / 255.0;
    modifiedG = rgb.G / 255.0;
    modifiedB = rgb.B / 255.0;

    k = 1 - new List() { modifiedR, modifiedG, modifiedB }.Max();
    c = (1 - modifiedR - k) / (1 - k);
    m = (1 - modifiedG - k) / (1 - k);
    y = (1 - modifiedB - k) / (1 - k);

    return new CMYK(
        (byte)Math.Round(c * 100),
        (byte)Math.Round(m * 100),
        (byte)Math.Round(y * 100),
        (byte)Math.Round(k * 100));
}

Link - https://github.com/iamartyom/ColorHelper/blob/master/ColorHelper/Converter/ColorConverter.cs