Question

If humans only have three kinds of color photo-receptors, how can we see so many different colors?

Answer 1

Because there are three kinds of cone cells, our eyes work by adding three signals to "see" different colors. The color you "see" depends on how much energy is received by each of the three different types of cone cells.

Step-by-step explanation:

Answer 2

Because our eyes mix the colors together, making new ones. (Purple,green, orange.) the rest of the colors depend on the light. So the light and receptors play a roll into seeing different colors.