This function creates change the luminescence of given color (0..1)

color_luminescence.js

  function generate(hex, lum) {

    // validate hex string
    hex = String(hex).replace(/[^0-9a-f]/gi, '');
    if (hex.length < 6) {
      hex = hex[0]+hex[0]+hex[1]+hex[1]+hex[2]+hex[2];
    }
    lum = lum || 0;

    // convert to decimal and change luminosity
    var rgb = "#", c, i;
    for (i = 0; i < 3; i++) {
      c = parseInt(hex.substr(i*2,2), 16);
      c = Math.round(Math.min(Math.max(0, c + (c * lum)), 255)).toString(16);
      rgb += ("00"+c).substr(c.length);
    }

    return rgb;
  }