Convert RGB color to CIE LAB color

rgb_to_lab.js

function rgbToXyz(r, g, b) {
  r /= 255
  g /= 255
  b /= 255

  if (r > 0.04045) r = Math.pow(((r + 0.055) / 1.055), 2.4)
  else r = r / 12.92

  if (g > 0.04045) g = Math.pow(((g + 0.055) / 1.055), 2.4)
  else g = g / 12.92

  if (b > 0.04045) b = Math.pow(((b + 0.055) / 1.055), 2.4)
  else b = b / 12.92

  r = r * 100
  g = g * 100
  b = b * 100

  //Observer. = 2°, Illuminant = D65
  return {
    x: r * 0.4124 + g * 0.3576 + b * 0.1805,
    y: r * 0.2126 + g * 0.7152 + b * 0.0722,
    z: r * 0.0193 + g * 0.1192 + b * 0.9505
  }
}


function xyzToLab(x, y, z) {
  var refX =  95.047
  var refY = 100.000
  var refZ = 108.883

  x /= refX
  y /= refY
  z /= refZ

  if (x > 0.008856) x = Math.pow(x, 1/3)
  else x = 7.787 * x + 16 / 116
  if (y > 0.008856) y = Math.pow(y, 1/3)
  else y = 7.787 * y + 16 / 116
  if (z > 0.008856) z = Math.pow(z, 1/3)
  else z = 7.787 * z + 16 / 116

  return {
    l: (116 * y) - 16,
    a: 500 * (x - y),
    b: 200 * (y - z)
  }
}