Protans are people with protanomaly, a type of red-green color blindness in which the red cones do not detect enough red and are too sensitive to greens, yellows, and oranges.
As a result, greens, yellows, oranges, reds, and browns may appear similar, especially in low light. It can also be difficult to tell the difference between blues and purples, or pinks and grays. Red and black might be hard to tell apart, especially when red text is against a black background.