Many people assume that dogs only see in black, white, and grey. The truth is that compared to humans, dogs are “colorblind”. However, like us, they can see shades of blue, yellow, and brown. What they cannot see are shades of green, red, and violet. This is because dogs have two different types of cones in their eyes whereas most humans have three. Cones allow brains to interpret different wavelengths of light as different colors, and the more cones an animal has, the more colors it will see. In fact, a dog’s eyesight is similar to a person who has red-green colorblindness.
When dogs look at objects that are in shades of green, red, or violet, they will see them in shades of colors they can actually interpret. For instance, your dog will likely its red collar and the green grass it’s playing on as dark yellow. So the next time you’re picking out a new ball for your pup, choose one in blue or bright yellow since it will stand out on the dull-colored ground. Click here for some side by side images of what humans and dogs see differently.
Another difference in human and canine eyes is that while humans have more cones than rods in their eyes, dogs are more rods than cones. Rods are cells that help the brain interpret movement and low-light vision. Dogs have much more rods than humans do making them better with night vision and detecting movement. This has been helpful to dogs because they have evolved to be nocturnal hunters.
However, while we may consider dogs colorblind, there are other animals that would call us colorblind. There are many birds and fishes that have a fourth type of cone to see ultraviolet light, and butterflies have AT LEAST 15 different photoreceptors (light-detecting cells similar to the cones in our eyes).
Sources: https://www.psychologytoday.com/us/blog/canine-corner/200810/can-dogs-see-colors https://www.akc.org/expert-advice/health/are-dogs-color-blind/ http://animalnecessity.com/blog/how-dogs-see-the-world/ https://www.sciencemag.org/news/2016/03/butterfly-has-extreme-color-vision