GPUImage 添加美颜、adobe photoshop curves file:acv等滤镜的Demo。
https://github.com/BradLarson/GPUImage
https://github.com/YuAo/YUGPUImageHighPassSkinSmoothing
http://blog.csdn.net/hhxxhbmy/article/details/46658731
https://filtergrade.com/free-curves-presets-for-photoshop/
http://onixa.deviantart.com/art/Photoshop-Curves-Pack-121882919