Final answer:
Gray is called a tone because it creates a gradation of the original color by reducing its saturation, altering its value, and changing how it is perceived. This has a significant impact on the art by adding depth and affecting mood.
Step-by-step explanation:
Gray is referred to as a tone when added to a color because it creates a gradation of the original hue, resulting in a subtle change in its appearance. This tonal variation is achieved by mixing a color with gray, which is made by combining two complementary colors. The presence of gray modifies the intensity of the original color, typically reducing its saturation and altering its visual perception. For instance, a bright red mixed with gray can become a muted red, which has a different impact in art. Additionally, this tonal change can affect the value of a color, which pertains to its lightness or darkness. Artists utilize these variations to add depth, create a particular mood, or emphasize certain aspects of their work.
In the context of simultaneous contrast, the presence of gray next to a color can affect how we perceive that color. Gray can appear to take on a tint of the complementary color of its surrounding hue, and can also influence the perceived intensity and value of adjacent colors. Shades and tints, which are created by adding black or white to a color, also contribute to the value of a color, producing lighter or darker variations, respectively. Through manipulating hues, tones, and values, artists can guide viewers' emotional responses and draw attention to specific areas within their compositions.