ここのサイト結構性能いいかも
ちょっと誰か試して

Let's Enhance – free online image upscale and enhancement with neural networks
https://letsenhance.io/

原画像
http://i.imgur.com/mxp9Q2J.png
http://i.imgur.com/TGaT3oX.png

waifu2x
http://i.imgur.com/s4jE2hO.png
http://i.imgur.com/UZsH9uj.png

Let’s Enhance
http://i.imgur.com/fu6PEWJ.png
http://i.imgur.com/SVpsLwH.png

紹介記事
This Website Uses AI to Enhance Low-Res Photos, CSI-Style
https://petapixel.com/2017/10/31/website-uses-ai-enhance-photo-csi-style/