A common perception among people is that dogs are color blind and can see a world that is purely black and white. Well, they are color blind, but in a completely different way. While their vision sensitivity and chromatic acuity is significantly less than humans, your canine friends can see color.
The only thing is that dogs see something like a human deuteranope, that is, they are red-green color blind. This is because of the presence of 2 cone types or light-sensitive cells, rather than 3 cone types that a human eye contains. So basically dogs have a blue-violent receptor range and the yellow-green receptor range.
Color Blindness in Dogs
Like the human eyes, the eyes of dogs contain light sensitive cells known as rods and cones. These are the parts that enable a human, as well as a dog, to distinguish colors and ascertain the details of a vision.
While rods allow us to distinguish shades of black and white, cones are the cells that are primarily responsible for visual acuity or sharpness. The presence of cones determine how well we see and also detect color.
Due to the presence of fewer cone cells in the retina and a higher density of rod cells, dogs cannot distinguish between red, orange, and green. They can only see various shades of blue and yellow and can possibly differentiate between closely related shades of gray that are not distinguishable to people.
Moreover, they cannot understand the finer details of a scene. While we see 20/20 or a little better, the dogs see about 20/80. This would make the scene around three to four times blurrier!
So how does your dog identify and chase the orange ball on the green grass? Well, the higher concentration of rods can help it discern the visual information in dim light. They have sensitive motion detectors. So while an orange ball on the green grass may appear as yellow against yellow to your dog, the motion of the ball helps it catch it anyway.
The perception of depth and accuracy of the vision was an evolutionary essential for a primate, from which we humans have evolved. This allowed the primates to jump from one tree to the other and choose the best fruits based on its color.
Dogs have evolved from species that need to hunt, especially ones which are camouflaged at night. Therefore, the night vision of the dogs is enhanced by the presence of more rods and a structure called the Tapetum Lucidum. They can survey a large field of view to scan for their prey, have maximal contrast, and detect the slightest of motion.
In 1989, researchers Neitz, Geist, and Jacobs concluded that although the dogs are color blind, they can see certain colors. This along with a sense of motion, ability to detect contrast, view things at night, and a wider field of view enable dogs to hunt their prey at night.