afterimage
an optical effect in which an additional color seems to appear at the edge of an observed color.
successive contrast
a visual phenomenon that creates complementary afterimages of a color after gazing at it for a brief but sustained period of time.
simultaneous contrast
the effect two neighboring colors have upon each other as their afterimages interact along a shared border
complementary contrast
when two colors with even a suggestion of complementary relationship are placed next to each other, that relationship is emphasized because of simultaneous contrast.
ground subtraction
grounds subtract their own qualities from colors that they surround.
vibration
vibration occurs when blocks of very different colors that are close or equal in values are placed next to each other. The colors appear to shimmer and lose their edges.
spreading effect
when a dark line is drawn onto an idle-value ground, the entire ground appears darker, while a light line would make the ground appear lighter. The lightness/darkness of the line seems to spread into the ground.
When forms are outlined with a dark line, they all seem darker. When a light line is used, they appear lighter.
contrast of extension
also referred to as proportion, contrast of extension refers to the relative areas of two or more colors in a composition. Designers call the color with the largest proportional area the dominant color (the ground), while smaller areas are called subdominant colors. Accent colors are those with a small relative area, but offering a contrast because of a variation in hue, value, or saturation.
Sources: Color – A Workshop Approach by David Hornung and Understanding Color by Linda Holtzschue
Color Glossary IV
