I've often heard it said that dogs see only in Black and White. This is a myth, though. Dogs see in color, just not the same way that humans see color.
For example, dogs see red, green, orange and yellow as... yellow. Dogs can see various shades of blue and purple. They can even differentiate shades of gray better than humans. So, while humans can see the full spectrum of colors, dogs are a bit limited.
However, they are far more outstanding than humans in their ability to see in dim or flickering light, respond quickly to an image, and detect even the slightest motion.
So while your pooch may not see the entire rainbow, he does see color, and his vision is superior to humans in other ways.
For a detailed description of some of the research that has been done on this topic, follow this link.
I'll end this by saying that one of the prettiest black and white dogs is the Dalmatian. When my son was little-bitty, he used to say he wanted to be a Dalmatian when he grew up. I can see why!