Pigments.

The pigments we use in painting absorb a wavelength range of the light that enters them, and reemit the remainder. Let us assume that a certain pigment receives white light that contains the full color spectrum, and that it absorbs light in the color range marked with the white arc on Fig. 8. The color of the light it emits then changes as indicated by the arrow. A pigment absorbing blue light will therefore emit the complementary color, which is orange. The exact effects of mixing pigments must be determined by experimentation, but the color of the resulting mixture is that which results from the absorptions by its components. The ‘primaries’ for the palette of pigments are therefore the complementaries of red, blue and green, that is, cyan (blue-green), yellow and magenta (Fig. 9, right). These are the ones used in color printing.

As we mix pigments, the saturation diminishes, and so does the brightness. A mixture of the three primaries gives black. If we wish to increase the brightness of a mixture, we must add white pigment (or, in transparent watercolor, let the white paper shine through). The colors of pigments are not fully saturated and our palette would be incomplete if we were to use three primaries and white only. But black can be approximated quite well by mixing pigments (for instance, alizarin red, cadmium yellow and ultramarine blue). Such mixtures, which still may conserve some tinge other than pure black, are often preferable to the pure black that comes in the tubes.

Fig. 8

Fig. 9

Since simplification is part of the artistic process, we usually chose a relatively small range from the thousands of colors that are available. Our first instinct is to apply to depicted objects their object, or local, colors. But the perceived colors depend also on the illuminating light. (Fig.10).

Fig. 10 Fig. 11. (Bonnard)

Features that contrast in color or in brightness with their surroundings attract our attention. Complementary colors are often used, such as the orange of the tower, figure 7.

Two colors only are often sufficient for the desired effect (Bonnard, Fig. 11. Usually one color is dominant due to its area, central position, or saturation. When the contrast in the picture is mainly one of brightness, a very narrow range of colors can be used successfully, (Fig.12). On the other extreme, strong color contrasts can be used when the colors are applied flat (Fig. 13). To emphasize emotional aspects, we can freely change colors as well as shapes. From the expressionists onward, colors have been chosen frequently for emotional value (Fig. 14).

Fig. 12 Fig. 13

Fig. 14. (Derain)

The contrasts of hue and saturation may vary greatly from one picture to another, but all paintings show contrast of light and dark; even the pure saturated colors cover a range of brightness, from yellow to deep blue and violet, as can be seen on a grayscale reproduction of the color

triangle (Fig. 15).

Fig. 15

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