Cone cells are adapted for seeing in brighter light and can detect different colors of light. Humans have three types of cones. Dogs have two types of cones. Evidence suggests that the dog has vision similar to a human who is red-green color blind. Cats have three types of cones, like people, but do not have exactly the same color vision as we do.
Cats live in a world of fuzzy pastels.
Dogs and cats appear to respond to blue and yellow best, and seem to have more trouble with green and red. Colors that would appear very rich to us are more pastel-like to the cat. The cat sees a green, grassy lawn as a whitish lawn, and a green rose-bush as a whitish bush with dark flowers. Humans see 30 cycles per degree, horses 18, dogs 12 and cats 6. Acuity in dogs is 0.4 times that of people, 0.67 times that of horses, and twice that of cats.