How to get inference mask image , in which RGB values  are correlating to cityscapes original label ids?

I  have added seg_map= sess.run(raw_output_up)  in inference.py line112 and get mask images.
However it's not related to cityscapes original label ids. 
Could you tell me how can i get inference mask image, in which RGB values  are correlating to cityscapes original label ids? @hellochick thank you a lot