Along with superior night vision, dogs have better motion visibility than humans have. Dogs see like a color-blind human. Dogs' retinas can distinguish two colors. These colors are blue-violet and yellow. Dogs can also differentiate between shades of gray.
Dogs are unable to recognize green, yellow, orange, and red.
This, along with the flow and noise of traffic, tell the dog that it is the right time to cross the street. How a dog's eyes are set determines the field of view as well as depth perception. Prey species tend to have eyes located on the sides of their head. This gives the animals an increased field of view and allows them to see approaching predators. Predator species, like humans and dogs, have eyes set close together.