Test yourself: How color blind are you?

I definitely know I'm tone deaf. But I've often wondered if I'm also somewhat color blind. So many times I insist something is black when people are telling me it's a dark navy blue, or something is brown when people tell me it's a certain shade of green. Yet according to this test I'm fine. I scored 15 out of 15. Maybe everyone else is color blind?

Take the test here.