I came across this test on the X-Rite site a few months ago when I was researching one of their monitor calibration systems. It’s an informative and fun test that will show exactly where you might have problems with color perception. I’ve had enough arguments disagreements with friends and family over the years about certain blue/green colors to guess that I had a very common male-linked weakness in that area. Sure enough the test showed me right where it was. Just rearrange the colors till they look like they are in order. Give it a try at the X-rite Online Color Challenge.