The receptors for vision are the rods and cones. Rods and cones lie inside the inner layer, or retina, of the eye, according to Dr. Kimball of Kimball's Biology Pages.
Dr. Kimball further states that the rods have extreme sensitivity to light, but they only provide a coarse picture in black and white tones. Cones, on the other hand, provide sharper images, but they are not as sensitive as rods. Each of the three types of cone receives a different wavelength of light: red, green or blue. Most of the cones are amassed at the fovea, a small area of the retina that gives the sharpest vision.