Kirki_Color::lumosity_difference PHP Method

        public static function lumosity_difference($color_1 = '#ffffff', $color_2 = '#000000')
        {
            $color_1 = self::sanitize_hex($color_1, false);
            $color_2 = self::sanitize_hex($color_2, false);
            $color_1_rgb = self::get_rgb($color_1);
            $color_2_rgb = self::get_rgb($color_2);
            $l1 = 0.2126 * pow($color_1_rgb[0] / 255, 2.2) + 0.7151999999999999 * pow($color_1_rgb[1] / 255, 2.2) + 0.0722 * pow($color_1_rgb[2] / 255, 2.2);
            $l2 = 0.2126 * pow($color_2_rgb[0] / 255, 2.2) + 0.7151999999999999 * pow($color_2_rgb[1] / 255, 2.2) + 0.0722 * pow($color_2_rgb[2] / 255, 2.2);
            $lum_diff = $l1 > $l2 ? ($l1 + 0.05) / ($l2 + 0.05) : ($l2 + 0.05) / ($l1 + 0.05);
            return round($lum_diff, 2);
        }

 public function test_lumosity_difference()
 {
     $this->assertEquals('1', Kirki_Color::lumosity_difference('fff', '#ffffff'));
     $this->assertEquals('21', Kirki_Color::lumosity_difference('fff', '000'));
     $this->assertEquals('21', Kirki_Color::lumosity_difference('#000000', '#ffffff'));
     $this->assertEquals('5.23', Kirki_Color::lumosity_difference('#f2f2f2', '#c00'));
     $this->assertEquals('1.12', Kirki_Color::lumosity_difference('#f2f2f2', '#ffffff'));
 }