You dont actually see anything in a dream. Based off of what your brain is chaining about. It should skip the process of visualizing and just go straight to analyzing. Your brain is just translating random memories so there is no actual color yet you can differentiate from yes and no. (which is also why most dreams cant be remembered)
While approximately 80 percent of all dreams are in color, there are a small percentage of people who claim to only dream in black and white. In studies where dreamers have been awakened and asked to select colors from a chart that match those in their dreams, soft pastel colors are those most frequently chosen.
I have had both color and B&W dreams. But usually, for me it's like this. The nightmares always seem to be in color, i.e., high in detail. And the good dreams I have are usually, in B&W. I have no idea why.