I. Dogs can distinguish colors, but not the colors that people recognize

The most commonly mentioned problem with dog vision is that dogs are color blind and can see black, white, and gray. Scientific studies have proven that dogs can see in color, but they just can't see the full-color spectrum as humans can, and they don't see as many or as many colors as humans do.

What is the difference between the visual structure of dogs and humans?
Both human and dog eyes contain special light-trapping cells, which are also called optic cone cells, and these cells allow our eyes to respond to color. However, seeing color depends not only on the number of vertebrae possessed but also on how many types of vertebrae are possessed, as each receives different wavelengths of light. Humans have three different kinds of visual cone cells, red, green, and blue vertebrae, and their combined activity provides a full range of color vision for humans. Dogs, on the other hand, have only two types of visual cone cells, fewer than humans, which is why their color vision is not as rich as ours. The most common color blindness in humans is because it is due to the lack of one of the three vertebrae, only two, but they can still see colors just as well, just less than normal, which is similar to color vision in dogs because dogs also have only two types of cone cells.

Experiments on color vision in dogs
Jay Neitz (Jay Neitz) of the University of California, Santa Barbara, did an experiment on color vision in dogs. During the experiment, the dogs were given three color swatches with a total of two different colors, two swatches that had the same color and another swatch that was a different color. The dog's task is to find the different colors of the color plate, as long as it finds the right, there will be a corresponding reward, as a way to motivate the dog to find out the different colors. After repeating the experiment several times, it is not only proved that the dog can see the color but also indirectly proved that the dog cannot see certain colors.

What colors can dogs see?
Instead of seeing the rainbow as what we think of as red, orange, yellow, green, blue, and purple, dogs will see it as dark blue, light blue, gray, light yellow, dark yellow (kind of like brown), and very dark gray. In other words, in the visual world of dogs, the colors that can be seen are blue, gray, and yellow.
Now know that dogs can only see yellow, gray, and blue, associated with life, I wonder if you have found their dogs look at the color of any different reactions? You can look at your own dog's toys, and buy what color, usually what color is the dog's favorite toy, is not yellow, gray, or blue. If you throw a red ball in the yard, you will find that the dog will have trouble finding it because red is not a conspicuous color for him. Or you can try it out and see if your dog reacts differently to you the next time you wear a different color of clothing.
In everyday life, we can also find dog-related products, such as leashes, collars, and toys, many are orange and blue, next time the owner the purchase products, you can tend to

Pick colors that are visible to the dog and you may find more of his preferences.

II. Dogs are not color blind? It's is the world is not black and white

In the relatively early days, it was thought that dogs were colorblind, that they could only see black and white. As scientific research has evolved and progressed over time, many studies have shown that the notion that dogs can only see white and black is not true and that dogs can see color and light through cones, rods, and ganglion cells.

We compared the number of cones and rods (respectively) in humans to the number of cones and rods in dogs and found that humans have 20% more cones than dogs, but dogs have many more rods than we do. Although we do not know the exact number of dogs, they are five times more sensitive to light than we are.

In addition, people project objects onto the retina through their eyes, forming images that allow us to see external objects.

About color
In human vision, "trichromatic" is perceived, which means that we can see three colors through the cones: blue, green, and red, or the three primary colors. And through the interaction of the three primary colors, we can see a variety of different colors, about 100,000 kinds.
In the dog's vision, they perceive "dichromatic", dogs can only see blue and yellow, and through the interaction of these two colors (tonal), they can see 10,000 kinds of colors.
When we understand the world of colors that dogs can see, we find that some agility training equipment is usually in a blue or yellow color scheme, so that dogs can see the training equipment and the very important "buttons" (yellow parts) that they must touch.
So we can now know that in a dog's color system, it can't see red at all, so when we are choosing toys to buy for our dogs, we need to think about whether to buy blue or yellow, especially if we plan to take these toys out outdoors for our dogs to play with, and we need to know that green and blue, look the same to our dogs.

The dog's eyesight
Dogs have a very open field of vision, and they have a field of view angle of about 250 degrees, while humans have a field of view angle of only 190 degrees.
Of course, because dogs have a large pupil and a fuzzy felt layer, their eyes also have very good night vision, and the large pupil can act as a mirror to reflect light, giving the eye more opportunity to absorb photons and thus see more in the dark.
Dogs in looking at moving objects, then we humans to be more acute; can be in the vision to watch the degree of distance, we humans can see a little farther than dogs, assuming we can see 10 meters away, dogs may only be able to see 2, 3 meters away from the object.
When we know what color the world is in the eyes of the dog, we have a more understanding of dog behavior, and habits, we will also understand why the red toy is thrown into the grass dog is so difficult to find, and we will also give more consideration to the dog after the choice of toys, supplies.
Look at your home and your dog supplies, there is no blue and yellow, and in the eyes of the dog are the same other color things?
Dogs are very amazing animals, they have a superb motor ability, there are also called the supernatural sense of smell, coupled with their radar-like ears, dogs in daily life can do a lot of things that people can not do, such as the final criminal with the nose, with ears alert around, etc... But nature is fair, when it gives the dog so many specialties, nature deprived of another part of the ability, that is, its vision, many people say that the dog's eyes in the world are black or white, that is, this guy is color blind, is this true?

Compared people is indeed color blind, but their eyes in the world are not black and white, they can also distinguish the part of the color, scientists have done an experiment, let the dog identify different types of colors, and eventually determined that the dog can still see the yellow, blue and purple three colors, so dogs see the color although not as rich as humans see, but not only black and white. This is so because humans have three different types of visual cone cells, however, dogs only have two, so dogs are a little weaker to distinguish details and colors of objects.