First, cats can distinguish blue, purple, green and yellow. For colors such as red, brown and orange, cats only see black to gray levels. Although they cannot see the colorful world like humans, cats have strong night vision. In the dark, cats’ pupils can expand to 90% of the eyeball surface. As long as there is weak light, they can capture prey. . The second is dogs, which can distinguish different shades of purple, blue and indigo, but have no special sensitivity to colors such as red and green. Studies have shown that red is a dark color in the eyes of dogs, while green is white. Although dogs' eyesight is not as good as that of humans, they have very sensitive senses of smell and hearing, which largely make up for their shortcomings in vision.