调研内容 (natural pictures, scanned documents)
1. state-of-the-art on digital image manipulation
2. Evaluation criteria (quantitative / qualitative)
一、image types
1、pictures(图片，绘画作品) / natural images（自然图像）
2、scanned documents（扫描文件）
二、methodology
traditional (low-level image processing)低级图像处理
deep learning (GAN)
三、evaluation criteria / performance metrics
1、human-based / subjective, user study
2、ground truth based / objective：
- 常用IS（inception score）和FID（Fréchet Inception Distance）
- DIPD用于测量内容保留
- CIS
四、Goal of image manipulation
fool the human
fool the AI (model-dependent)