Rgb color to lab - Node.js CSS

Node.js examples for CSS:Color

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Description

Rgb color to lab

Demo Code

//*************************
////from w  w  w.j  av a  2 s .c o m
//  color utilities
//
//  rgb_to_lab(r,g,b)
//
//*************************
function rgb_to_lab(r,g,b){
  //** RGB[0..1] -> XYX[0..1] 
  var R,G,B,X,Y,Z;
  R = r / 255;
  G = g / 255;
  B = b / 255;
  X = 0.412453 * R + 0.357584 * G + 0.180423 * B;
  Y = 0.212671 * R + 0.715169 * G + 0.072169 * B;
  Z = 0.019334 * R + 0.119193 * G + 0.950227 * B;
  //** XYZ[0..100] -> L*a*b*
  var Xr,Yr,Zr;
  X = X * 100;
  Y = Y * 100;
  Z = Z * 100;
  Xr = 95.045;
  Yr = 100;
  Zr = 108.892;
  X = X / Xr;
  Y = Y / Yr;
  Z = Z / Zr;
  var l,a,b_;
  l  = 116 * color_f(Y) - 16;
  a  = 500 * ( color_f(X) - color_f(Y) );
  b_ = 200 * ( color_f(Y) - color_f(Z) );
  result = {l: l,a: a,b: b_};
  return result
}

function color_f(t){
  if(t > 0.008856){
    return Math.pow(t,1/3);
  }else{
    return (903.3 * t + 16)/116;
  }
}

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