Library fails to compile on Linux?

[ghost]

I don't know why, but there's a LOT of undefined references to `XOpenDisplay'

[dtschump]

You have to link your executable against libX11 and libpthread, which means adding -lX11 -lpthread to the compilation command line (if you use g++). Otherwise, you may want to disable the display capabilities of CImg, by setting cimg_display=0.