cmyk-to-rgb.js

/*  Adapted from pdf.js's colorspace module
    (https://github.com/mozilla/pdf.js/blob/a18290759227c894f8f97f58c8da8ce942f5a38f/src/core/colorspace.js)

    Released under the Apache 2.0 license:
    https://github.com/mozilla/pdf.js/blob/master/LICENSE
*/
/**
 *
 * @param {[number,number,number,number]} src CMYK values (0-100)
 * @returns {Uint8ClampedArray} RGB values (0-255)
 */
module.exports = function convertToRgb(src) {
  const toFraction = 1 / 100
  const rgb = new Uint8ClampedArray(3)

  const c = src[0] * toFraction
  const m = src[1] * toFraction
  const y = src[2] * toFraction
  const k = src[3] * toFraction

  rgb[0] =
    255 +
    c *
      (-4.387332384609988 * c +
        54.48615194189176 * m +
        18.82290502165302 * y +
        212.25662451639585 * k +
        -285.2331026137004) +
    m *
      (1.7149763477362134 * m -
        5.6096736904047315 * y +
        -17.873870861415444 * k -
        5.497006427196366) +
    y * (-2.5217340131683033 * y - 21.248923337353073 * k + 17.5119270841813) +
    k * (-21.86122147463605 * k - 189.48180835922747)

  rgb[1] =
    255 +
    c *
      (8.841041422036149 * c +
        60.118027045597366 * m +
        6.871425592049007 * y +
        31.159100130055922 * k +
        -79.2970844816548) +
    m *
      (-15.310361306967817 * m +
        17.575251261109482 * y +
        131.35250912493976 * k -
        190.9453302588951) +
    y * (4.444339102852739 * y + 9.8632861493405 * k - 24.86741582555878) +
    k * (-20.737325471181034 * k - 187.80453709719578)

  rgb[2] =
    255 +
    c *
      (0.8842522430003296 * c +
        8.078677503112928 * m +
        30.89978309703729 * y -
        0.23883238689178934 * k +
        -14.183576799673286) +
    m *
      (10.49593273432072 * m +
        63.02378494754052 * y +
        50.606957656360734 * k -
        112.23884253719248) +
    y *
      (0.03296041114873217 * y + 115.60384449646641 * k + -193.58209356861505) +
    k * (-22.33816807309886 * k - 180.12613974708367)

  return rgb
}