Color difference in RGB and LAB

colorDiffUtil.js

/**
 * Compare color difference in RGB
 * @param {Array} rgb1 First RGB color in array
 * @param {Array} rgb2 Second RGB color in array
 */
export function deltaRgb (rgb1, rgb2) {
  const [ r1, g1, b1 ] = rgb1,
        [ r2, g2, b2 ] = rgb2,
        drp2 = Math.pow(r1 - r2, 2),
        dgp2 = Math.pow(g1 - g2, 2),
        dbp2 = Math.pow(b1 - b2, 2),
        t = (r1 + r2) / 2

  return Math.sqrt(2 * drp2 + 4 * dgp2 + 3 * dbp2 + t * (drp2 - dbp2) / 256)
}

/**
 * calculate the perceptual distance between colors in CIELAB
 * https://github.com/THEjoezack/ColorMine/blob/master/ColorMine/ColorSpaces/Comparisons/Cie94Comparison.cs
 * 
 * @param {Array} labA First LAB color in array
 * @param {Array} labB Second LAB color in array
 */
function deltaE(labA, labB){
  var deltaL = labA[0] - labB[0];
  var deltaA = labA[1] - labB[1];
  var deltaB = labA[2] - labB[2];
  var c1 = Math.sqrt(labA[1] * labA[1] + labA[2] * labA[2]);
  var c2 = Math.sqrt(labB[1] * labB[1] + labB[2] * labB[2]);
  var deltaC = c1 - c2;
  var deltaH = deltaA * deltaA + deltaB * deltaB - deltaC * deltaC;
  deltaH = deltaH < 0 ? 0 : Math.sqrt(deltaH);
  var sc = 1.0 + 0.045 * c1;
  var sh = 1.0 + 0.015 * c1;
  var deltaLKlsl = deltaL / (1.0);
  var deltaCkcsc = deltaC / (sc);
  var deltaHkhsh = deltaH / (sh);
  var i = deltaLKlsl * deltaLKlsl + deltaCkcsc * deltaCkcsc + deltaHkhsh * deltaHkhsh;
  return i < 0 ? 0 : Math.sqrt(i);
}