https://blog.wongcw.com/2018/10/20/%e7%94%a8%e4%ba%8e%e7%a7%bb%e9%99%a4%e5%9b%be%e7%89%87%e8%83%8c%e6%99%af%e7%9a%84-web-%e5%ba%94%e7%94%a8%ef%bc%9aclipping-magic/
用于移除图片背景的 Web 应用:Clipping Magic