Although many people believe that dogs only see in black and white, these animals are actually red-green colorblind. This means that dogs can see yellow and blue, but they cannot see red or green.
A special type of cell called a cone is what allows animals to see color. Dogs have two types of cones, while humans generally have three. This causes dogs to have a more limited ability to perceive colors than most humans. When dogs see red or green objects, they perceive them to be different colors or shades of gray. For example, a purple object appears blue to a dog.