Dogs can see some colors, but their color vision is more limited than that of humans, and they primarily see yellows, blues and grays. Dogs cannot see red, orange, violet and green.
Both human and canine eyes rely on a special type of cell called a cone to discern colors. Different cones pick up various colors on the spectrum. Typical dogs have two types of cones, giving them the ability to see yellows and blues. Typical humans have three cones, which adds the ability to see the full color spectrum. Some colorblind humans only have two cones, giving them color vision similar to that of dogs. In addition to examining the structure of the eye, behavioral tests have been performed to prove that dogs see limited colors.
When a dog sees an object that is not yellow, blue or grey, it still perceives it as one of those three colors. For example, dogs see green objects as yellow and violet objects as blue. If an object in between yellow and blue on the color spectrum, a dog sees shades of grey. Colors are also less intense for dogs than humans.