https://blog.wongcw.com/2020/10/15/%e6%b5%b7%e7%9b%9c%e8%88%b9%e6%8e%a8%e5%87%bak60-rgb%e5%b0%88%e6%a5%ad%e6%a9%9f%e6%a2%b0%e9%81%8a%e6%88%b2%e9%8d%b5%e7%9b%a4/