C# Round Color to Colors in a list

Question

I have a list of colors in HEX format:

String[] validcolors = new String[]
{
    "0055A5",
    "101010",
    "E4D200",
    "FFFFFF",
    "006563",
    "A97B3E",
    "B80000",
    "6E3391",
    "D191C3",
    "D68200",
    "60823C",
    "AA8D73",
    "73A1B8",
    "6E6D6E",
    "00582C",
    "604421"
};    

And a color object:

Color c = ...

I want to find the color that is closest to c in validcolors. Can somebody help me out? My initial idea was 'closest by RGB value', but whatever works is fine.

Answer 1

I would think of transforming the hex to .NET color then calculating somr sort of distance ((x2-x1)²+(y2-y1)²) and taking the closest using this distance:

string closestColor = "";
double diff = 200000; // > 255²x3

foreach(string colorHex in validColors)
{
    Color color = System.Drawing.ColorTranslator.FromHtml("#"+colorHex);
    if(diff > (diff = (c.R - color.R)²+(c.G - color.G)²+(c.B - color.B)²))
        closestColor = colorHex;
}

return closestColor;

Answer 2

The distance between two colors depends on the color model you are using. See this article in the Wikipedia so until we know what model you prefer we can't help.