How to convert Hex to RGB?

Question

I am trying to use this to figure out if a color is light or dark

Evaluate whether a HEX value is dark or light

Now. It takes in a int

 float calcLuminance(int rgb)
 {
      int r = (rgb & 0xff0000) >> 16;
      int g = (rgb & 0xff00) >> 8;
      int b = (rgb & 0xff);

      return (r*0.299f + g*0.587f + b*0.114f) / 256;
 }

I have a hex color though.

I tried to do this

  var color = System.Drawing.ColorTranslator.FromHtml("#FFFFFF");
  int rgb = color.R + color.G + color.B;
   var a = calcLuminance(rgb);

I got 0.11725 I thought it would have to be in the range of 0-256 or something like that.

What am I doing wrong? Do I have to covert R to an int? Or am I just way off?

Answer 1

You can use:

public string GenerateRgba(string backgroundColor, decimal backgroundOpacity)
{
 Color color = ColorTranslator.FromHtml(hexBackgroundColor);
 int r = Convert.ToInt16(color.R);
 int g = Convert.ToInt16(color.G);
 int b = Convert.ToInt16(color.B);
 return string.Format("rgba({0}, {1}, {2}, {3});", r, g, b, backgroundOpacity);
}

Link To original Post by jeremy clifton on git