Why does color always cheat us? The multiple colors of black and white

Our visual system sometimes makes colors appear on a black and white image. How is this possible since the image objectively contains no spectral characteristic that can be interpreted as a color by our brain? We then speak of subjective colors because they differ from one observer to another, and some do not perceive them. It turns out that the time parameter plays a key role in the perception of these illusory colors. By what mechanism?