We are often asked what do dogs and cats see in terms of colour. Our pets rely heavily on their senses but see the world slightly differently than we do. Cats and dogs see much better in low light conditions than we do so they can hunt well. The minimum threshold of light for vision in cats is six times lower than that for humans. Dogs are a little less, but still a lot better than humans. Dogs however have less acute vision than humans. A dog would have to be within 6 metres of an object to clearly visualise details that we could see in 23 metres. Dogs also have a wider field of view than humans but their binocular vision and therefore ability to determine depth is not as good. They may be better at perceiving motion.
The most interesting aspect though is colour vision. A number of studies have been done to investigate the colour vision of dogs. It seems that dogs do possess and use colour vision but not to the same degree that humans do. It appears that the visual spectrum in dogs is divided into two hues, one colour range appears as blue and another is probably seen as yellow. Light that appears blue green to people appears as white or shades of grey to dogs. Dogs are also unable to differentiate between colour that appears as green, yellow-green, orange or red to people and are unable to differentiate greenish-blue from grey. This is similar to people who are red-green colour blind.