This is determined by the expressive meaning of dreams.
Most dreams are black and white. Is to highlight the plot of the dream, the plot is the key, and ignore the unimportant colors. You didn't notice the color in the dream at all, so you will think it was a black and white dream in retrospect.
Colorful dreams. Most of them are beautiful dreams, expressing beautiful feelings and longings. The colors in dreams will be extremely vivid.
There is also a dream, that is, most of them are black and white, but some specific things show colors.
At this time, the color in the dream will have special symbolic significance. For example, red may symbolize danger and warning. Green represents vitality.
Dreams are exquisite, and everything they show is incidental.