In painting, the surface area counts far more than it does in drawing. You know the principle, which is that there are no colored lines, only colored areas. The line, as a means of abstract graphic expression, can only enclose spaces and separate them from one another; it is color which sets off the surface.
In drawing, the line is about the only way to contrive a convincing illusion of space. The line can be used with similar effect in painting too, but it is not a specifically pictorial means of expression. Apart from the fact that a polychrome picture is always more effective than a colorless or monochrome one, color can be used to render the illusion of space much more clearly than lines or tinted surfaces.
Whether you are doing a pure line drawing or a drawing with tinted surfaces, you must adjust the scale of objects to their diminishing size as they approach the horizon or vanishing point, if you are to create an illusion of space.
This is not the case with color, but you can conceive light or dark areas to the point where the colors vanish. It is entirely a matter of circumstance whether you fix on light or shade; looking outwards from a woodland glade, the colors vanish into light, while looking inwards from the edge of the wood, they seem to vanish into darkness. Furthermore, strong colors push weaker ones into the background, just as pure colors appear nearer than impure ones. Where shades are of the same strength, red and yellow advance more than blue, and warm colors before cool ones. The following instance arises out of the different degrees of pervasiveness of the light rays, and it also determines the effect of color perspective: Imagine you are driving along a street with a clear view towards a traffic signal. You will hardly notice the green light from a distance, while the amber light will seem suddenly to leap unmistakably out at you, and the red light to recede. The red glass acts as a filter for the red rays from the white incandescent light which shines farthest, but as a color comes closer to a blue than to a yellow, so accordingly its effect is less aggressive.
On the other hand, drive along the same street in a really thick fog; from a corresponding distance away you will probably see neither green nor amber, but you will see the red light, and probably brake too soon. This is because against a dull gray background, the red seems to advance so much more in the absence of any other strong colors to judge by - that you are likely to underestimate appreciably your distance from the lights. Hence, it follows that you cannot produce an effect of perspective if you use only one color without any modulation, for instance, an even gray tone. You need the contrast with other colors. Similar contrasts will determine whether the foregoing should be reversed: pure intense blues can on occasion produce an effect of greater proximity than dull yellows and reds.
We may substitute "bright" for "dull" In the present context it is practically the same thing. Think back to the difference between additive and subtractive mixtures: a subtractive gray contains the same color components as an additive white. The differences are merely due to a loss of light through absorption.
Next: Light, Color and Distance