no not half there are several different types of colorblindness... it is just a common misconception that colorblind people only see black white and grey.
For me, I am Red/Green colorblind, also called Deutanope.
I can see the extreme reds and greens, but not close shades.
That exact same thing was in my text book for psychology. When the teacher was going over it there was a girl in the class who couldn't see the 3. She never knew she was color blind before that.