PCs are actually 2.2, Macs are 1.8 by default, which might look a little brighter or washed out as you might say. You can start off trying to change the gamma to 2.2 by going to System Preferences -> Display -> Color -> Calibrate -> Don't check "Expert Mode" -> 2.2 Television Gamma. If that doesn't help, you can try Expert Mode or use a program called SuperCal. In my experiences, calibrations by naked eyes are a little hard and depends a lot on external factors like your viewing angles, etc.