Contrast and Comparison
Like phenomena appear constantly in decoration. Whenever the treatment of a room is so arranged that the eye makes a comparison of similar lines of different lengths, or of similar shapes of different sizes, their apparent differences are increased by the contrast. Dining chairs placed against a vertically paneled wall appear lower and more squat by reason of the contrast between the lines of their backs and those of the paneling; small tables look even smaller in a big room, as do small rugs on a large floor space; a bookcase, highboy, chest of drawers or piano will appear wider in a narrow space, narrower in a wide space; taller in a room with a low ceiling, and shorter in a room with a high ceiling.
For the same reason, whenever one dimension of a room or of any object is emphasized, the other dimensions are apparently diminished. A narrow bookcase, cabinet or chair appears to be taller than a wide piece of the same actual height, as a couch without a back seems to be longer than a high-backed settee of the same actual length. The practical importance of these considerations, which will be developed at length in the chapter on Proportion, lies in the fact that beauty and fitness in decoration are so largely dependent upon the apparent-as opposed to the actual-relationships in size and shape among the elements of a composition; and inasmuch as contrast is sure to change the apparent relationships in some degree the decorator must be prepared to foresee and allow for these changes.
Colors, even more than shapes, are affected by contrast. Color practice is in fact immensely complicated by the fact that a color is never seen by itself, but always in relation to other colors. These other colors react upon it, altering in some degree its appearance both in hue and in tone. Chevreui set forth the general principle involved in the formula: When the eye sees at the same time two contiguous colors, they will appear as dissimilar as possible, both in optical composition and in height of tone.
The changes effected by contrast in altering the height of tone of juxtaposed colors is illustrated by Figure 20. Here the small inner squares are all of exactly the same tone of gray, but they appear to grow progressively darker as the outer surfaces grow progressively lighter. The same phenomena appear when dark pictures or hangings are placed against light walls, or when light rugs are placed on a darker floor. Moreover they appear whether the juxtaposed surfaces are in tones of neutral gray, in tones of the same hue, or in tones of different hues, as when a light red pillow is placed against a dark blue sofa. In the latter case, however, there is a double effect. Not only will the red appear lighter and the blue darker in tone, but each hue will also appear to be slightly tinged with the complementary of the other. That is, the red will be slightly tinged at the point of contact with orange, and the blue with green.
This phenomenon, which is called simultaneous contrast and is described and illustrated in every good text-book on optics, is of less importance in decoration than in painting, because the decorative areas are larger and the textures coarser. Nevertheless it is sufficiently important to require careful study and constant watchfulness in practice. It may be observed by placing small squares of colored paper against differently colored backgrounds, or by means of lengths of plain drapery fabrics. If a piece of orange-colored velvet, for example, be held against successive backgrounds of black, white, ultramarine and green, it will seem to change color slightly with each background. Against black it will appear not only lighter but more golden, because the lighter or yellow element in its composition is more strongly accentuated by tone contrast than is the darker or red element. Against white it will appear both darker and more red, for the opposite reason. Against its complementary blue it gains in purity and brilliancy, and against green it becomes more reddish in hue, because it is tinged by the complementary of the green ground. Thus when red and blue are juxtaposed the red tends toward orange-red and the blue toward green-blue; yellow and green tend respectively toward orange-yellow and bluish green; green and blue toward yellowish-green and purple; and so on. When true complementary hues are juxtaposed each is made more brilliant by the contrast.
What is true of the spectrum colors is true of all their derivatives formed with black, gray and white, in direct proportion to the amount of white light in the color. Very light broken tones impart their complementaries more strongly than do darker tones, and are accordingly better adapted for the production of brilliant or elusive color effects. Simultaneous contrast is most marked when the two hues are in about the same tone. When dark colors are used with light the effect of simultaneous contrast is very slight. Contrast both in hue and in height of tone is made very much less marked by the use of materials of rough surface, coarse texture, or conspicuous design.