** first download caffemodel
http://eecs.berkeley.edu/~rich.zhang/projects/2016_colorization/files/demo_v2/colorization_release_v2.caffemodel
http://eecs.berkeley.edu/~rich.zhang/projects/2016_colorization/files/demo_v2/colorization_release_v2_norebal.caffemodel
python demo.py
ref: http://richzhang.github.io/colorization/