With just a crude sketch as input, an AI can generate photorealistic faces from it. 1.5 years ago, NVIDIA released a landscaping software that could produce similar results for backgrounds, but for a learning algorithm to achieve this with human faces is a totally different level of complexity.
"DeepFaceDrawing: Deep Generation of Face Images from Sketches" by Shu-Yu Chen, Wanchao Su, Lin Gao, Shihong Xia, and Hongbo Fu:
http://geometrylearning.com/DeepFaceDrawing/https://arxiv.org/abs/2006.01047
