Inasmuch as values are such an important factor in painting, photography, architecture, sculpture and in everything which appeals to the human organism through the doorway of vision, it is of interest to have a standardized value-scale. Textbooks on art usually include a scale of shades from white to black but such a scale should be standardized in order to have a definite meaning. From an acquaintance with pigments and with the practical requirements of a value-scale the author has proposed the fol lowing standardization which is applied to the nine values commonly used by the artist.
Reflection Reflection factor factor Value (per cent) Value (per cent) Black 0 to 10 Low light SO to 60 Low dark 10 to 20 Light 60 to 70 Dark 20 to .30 High light 70 to 80 High dark 30 to 40 White 80 to 90 Medium . 40 to 50 The whitest pigment reflects about 90 per cent of the total incident light and, although white is a relative term, those pigments which reflect 80 per cent or more of the incident light are commonly considered white. The ordi nary black pigments often reflect as much as 10 per cent of the incident light but usually less. These facts have formed the basis of this standardization and a value-scale can be di vided in this manner and subjected to measure ment. If the scale be printed upon the best grade of white paper the highest value will be about 80 per cent or slightly above and the lowest value will be somewhat under 10 per cent because the best black ink, under the conditions of printing, reflects an appreciable/ amount of the incident light. Such a stand ardization at least eliminates the ordinary cru-t dity of visual estimates and should have a) place in the scientific aspects of light and shade.
It is an obvious conclusion from the fort..;. going that the distribution of light and shade is not fixed by pigments hut depends upon the' relative illumination intensities as well. For exampb , a black pigment which reflects 10 per cent of the incident light will appear as bright under nine units of illumination as a white pig ment which reflects 90 per cent of the incident light will appear under one unit of illumination. If both pigments are perfectly neutral (without hue) they will appear identical under these conditions of illumination. This is often a startling
to those \\ ho u
In practice, color is seldom separated from values or distribution of light and shade and it has its influence upon values. For example, let us take two pigments, red and blue of a given tint or shade. They possess certain val ues or relative brightnesses under a given il lumination. Let us assume that their values are the same under daylight illumination, then under the illumination from a tungsten lamp the red will appear considerably brighter, not uncommonly twice as bright. On the value scale this change under the latter illuminant would often amount to enough to raise the value of the red to the next higher value. There are many interesting influences of color on light and shade as will be apparent from ob servation and from a study of the science of color. All of these have their place in the art of light, shade and color but unfortunately rela tively few artists are familiar with the under lying scientific principles. It is noteworthy fact that masterful artists are commonly fa miliar with the sciences underlying their art and this is to be expected because there is noth ing mysterious about art. Mysteries are merely facts which are not understood and to the sci entist in light, shade and color there are fewer mysteries in art than to the artist himself. It is true that the esthetics of light, shade and color have less scientific foundation than the physics and physiology of the subject but wsthetics is a science which is not yet com pletely explored or unraveled.
Having had a glimpse into various aspects of light and shade it should be of interest to note a few facts pertaining to nature. We go to nature for many lessons, for here we find a picture gallery containing an infinite variety of canvasses. Any individual scene is continu ally changing, so nature provides unlimited op portunities for studying light and shade as well as color. Some idea of the variety in nature's lighting is obtained when it is noted that on a cloudless day the direction of light from the sun varies throughout the day from horizontal to vertical and again to horizontal at sunset. Most of this time the sky is contributing from 10 to 30 per cent of the total light. Here we have a combination of a powerful directed light with a weaker light from the hemisphere of sky. Add to this variety that from an infinite number of different combinations of light from clouds, sky and sun, and end the brief review with the perfectly overcast sky, and it must he concluded that the light and shade effects in nature are numberless.