This is an alternative hexdump.
It's possible this might not render well on some terminal configurations. It uses black and bold black to render null bytes and other non printable characters; if those colors are actually black on a black background with your configuration then you won't see them. Change your color configuration to something more useful or submit a PR with a smarter solution, that will be appreciated.
This is a screenshot under solarized via @BestPig.
Thanks @Raaka for the screenshot on default OSX bellow.
