Wow, I got 0, apparently I have perfect colour vision. Given how much sunlight my eyes get abused with (sailing, windsurfing, gliding) I am actually shocked. My eyes feel weird after doing that test though...
This is actually a useful tool to me. Part of my job is training people in workplace incident investigation, and I use a number of tools to show people how their perception of reality can be fallible. Here's a classic example -
Same Colour Illusion. Cheers for the link!!