The fovea is a region of the retina that’s densely packed with cones, a type of photoreceptor (a cell that detects light). The other type of photoreceptor is the rod.
While <u>rods function at low light levels</u> and allow night vision, they can’t distinguish color. In contrast, <u>cones function at high light levels and provide color vision</u>.
That's why you can't perfectly distinguish colors in a dark place.