A common question is whether the dog sees in color or black and white and the truth is that they have the ability to see colors, but not in the same way we do. For dogs, the green, yellow, orange and red have no difference. It's kind of blindness to these colors. But the dog can differentiate violet, blue and green. Many scholars believe that the dog sees a yellow tone when you look at the red, green and yellow, and it would be exactly why he could not distinguish it.
In short, dogs see colors, but with fewer shades and less precision than us, we can distinguish about 10 million different colors and combinations
On the other hand, you have the ability to perceive so many shades of gray that is almost impossible to fully test this talent, because of our own limitations.
The most widely accepted explanation for this phenomenon is that the old canids, ancestors of our dogs, were night hunters and differentiation of gray tones was far more important than color vision.
And like all predators, dogs quickly identify moving objects. This was fundamental for their good performance in the hunt. Today there are still many races to "hunt with the vision" as greyhounds, whippets and almost all lebréis. This is a factor of the most developed in canine vision and can, in the open, to distinguish a cat-sized objects moving at nearly 1,000 m.
On the other hand can take to see a stationary object that you try to show to 1 meter away.
So it's easier to get the attention of your friend with movements and signals.
Therefore we can say that dogs see no better or worse than us, just do it in a different way.