Your eyes pick up color using a type of cell called cones in your retina. The same is true for dogs, though our cones aren't exactly 
the same.
Humans have three types of cones, "which enables us to see different shades of red, blue-violet, and green," says Alison Meindl, 
DVM, a veterinarian, and professor at Colorado State University.
Dogs have two types of cones that pick up blue-violet and yellow shades, says Lara Sypniewski, DVM, a professor of small animal 
medicine at Oklahoma State University.
This means that dogs see in a similar way to humans who are red-green colorblind. "They don't see red or green and they see 
everything in shades of blue and yellow," says Jay Neitz, Phd, a researcher and professor of ophthalmology at the University of 
Washington.
Humans may have the advantage in color vision, but dogs definitely have us beat in the realm of night vision. This is because 
dogs' eyes have more light-gathering power than ours, Neitz says.
A dog's retina is largely composed of cells called rods, which can sense light, even in very low-light conditions, says Sypniewski.
Dogs are especially good at sensing movement. "The increased number of rods in the dog's retina also increases their ability to 
detect motion," Sypniewski says. This ability can help them detect small prey like squirrels.
Dogs have a wider field of vision than humans. Dogs' eyes are set slightly farther apart than humans' eyes, so they can see further
 to the side in each direction.
Dogs have blurrier long-distance vision than humans. A human with perfect vision has 20/20 vision, while dogs have 20/65 to 
20/85. This means that "a dog must be at 20 ft. to read a letter that a human with 20/20 vision would be able to read at 65 or 85
 ft.," says Sypniewski.
Dogs have trouble seeing things very close up. Dogs can see objects clearly if they're at least 13 to 20 inches away from their 
eyes, "but if the object is closer, the image may be blurry," Sypniewski says. Humans can see objects slightly closer — about 10 
inches away from the eye
Dogs may recognize you by your shape and motion. "If your dog recognizes you from a distance, it is not because it can see the 
details of your face like a human would, but rather because of your shape or the way you move," Neitz says.

来源：Insider