Define and differentiate trichromatic theory and the opponent-process theory. Which theory most easily explains negative color afterimages?

Trichromatic theory claims that our receptors respond to three primary colors, or color vision depends on the relative rate of response by three types of cones. One type is most sensitive to short wavelengths (blue), another to medium wavelengths (green), and another to long wavelengths (red). Each wavelength prompts varying levels of activity in the three types of cones. The opponent-process theory of color vision claims that we perceive color not in terms of independent colors but in terms of a system of paired opposites--red versus green, yellow versus blue, and white versus black. The theory states that cells maintain a spontaneous rate of activity when unstimulated, increase their activity in the presence of, say, green, and decrease it in the presence of red. After prolonged green stimulation fatigues them, they become less active than usual, that is, they respond as if in the presence of red. Similarly, other cells would be excited by red and inhibited by green, excited by yellow and inhibited by blue, and so forth. The opponent process theory better explains negative color afterimages. If you stare for a minute or so at something red and look away, you see a green afterimage. If you stare at something green, yellow, or blue, you see a red, blue, or yellow afterimage. The trichromatic theory provides no easy explanation for these afterimages.