Paint Chainer the auto/semiauto colorlize survice by online.

[tkbd]

It can colorize a line-drawing image automatically or semi-automatically.
If you drawing a picture, you can try it a following site.
https://paintschainer.preferred.tech/

A following B/W images are made by Wings3D 3D object




It can coloring fully automatically, or you can also set some colors as hint information.
Tiresome fill paint work would be alleviated.

Aslo If you made a program, may be interested in that algolithm.
It is using "Chainer" which is deep learning framework.
https://github.com/pfnet/PaintsChainer