https://www.photopea.com/

https://www.gimp.org/?fbclid=IwAR2iQ7VBoPQwlnz08oGVc4kpf1-nQzKjsfCICtwpuXGGwvIeJYufoRKk2d8

ill(ai)

https://inkscape.org/?fbclid=IwAR2OufEjFsstZql4KsfhGaJ17ubp_WMDx0gdyB9SUpHGsAAdG1QV0RuDclE

http://photoblog.hk/wordpress/54992/%EF%BC%BBps%E6%8A%80%E5%B7%A7%EF%BC%BD%E5%88%A9%E7%94%A8-high-pass-filter-%E9%AB%98%E6%95%88%E7%84%A1%E6%90%8D%E5%9C%B0%E9%8A%B3%E5%88%A9%E5%8C%96%E7%85%A7%E7%89%87

http://photoblog.hk/wordpress/157423/%E7%B0%A1%E5%96%AE%E6%AD%A5%E9%A9%9F%E7%94%A8%E3%80%8Csurface-blur%E3%80%8D%E4%BE%86%E6%9C%89%E6%95%88%E9%8A%B3%E5%88%A9%E5%8C%96%E7%85%A7%E7%89%87