Kirki_Color::color_difference PHP Method

        public static function color_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);
            $r_diff = max($color_1_rgb[0], $color_2_rgb[0]) - min($color_1_rgb[0], $color_2_rgb[0]);
            $g_diff = max($color_1_rgb[1], $color_2_rgb[1]) - min($color_1_rgb[1], $color_2_rgb[1]);
            $b_diff = max($color_1_rgb[2], $color_2_rgb[2]) - min($color_1_rgb[2], $color_2_rgb[2]);
            $color_diff = $r_diff + $g_diff + $b_diff;
            return $color_diff;
        }

 public function test_color_difference()
 {
     $this->assertEquals('0', Kirki_Color::color_difference('fff', '#ffffff'));
     $this->assertEquals('765', Kirki_Color::color_difference('fff', '000'));
     $this->assertEquals('765', Kirki_Color::color_difference('#000000', '#ffffff'));
     $this->assertEquals('522', Kirki_Color::color_difference('#f2f2f2', '#c00'));
     $this->assertEquals('39', Kirki_Color::color_difference('#f2f2f2', '#ffffff'));
 }