monochrome can be other colors too.... his was mono-yellow and black.... or colorized to yellow (shades) and black tones.
I looked at the color palette for it and it doesn't have a large palette.
Wow that was the real color pretty much...the HDR version is just richer and more saturated. It was a yellow sky, look, this is just one normal picture (yes i used CS5 content aware to get ride of telephone wire)