On the actual web page the first line of its abstract:

"Even though over 70% of internet traffic today is digital media, the way images and video are represented and transmitted has not evolved much in the past 20 years (apart from Pied Piper's Middle-Out algorithm)."

From the PDF:

https://arxiv.org/pdf/1705.05823.pdf

The end of Section 2.2. ML-based lossy image compression Right above 2.3. Generative Adversarial Networks

Theis et al. (2016) and Ball ́ e et al. (2016) quantize rather than binarize, and propose strategies to approximate the entropy of the quantized representation: this provides them with a proxy to penalize it. Finally, Pied Piper has recently claimed to employ ML techniques in its Middle-Out algorithm (Judge et al., 2016), although their nature is shrouded in mystery.