input sketch, output ink wash painting
example:
--------0.1----------
preprocess to get sketch images.
added style loss
--------0.2----------
change resnet to resunet
--------0.3----------
(No updating anymore since I've found a better way to achieve this goal.)
discriminate mountain|tree|river|sky
based on https://github.com/junyanz/pytorch-CycleGAN-and-pix2pix