light & color; mahalaxmi

Question 1

name the three dimensions of color. Describe them in relation to shade selection in clinical practice.

Answer 1

color perception is described by three independent and objective variables shown in the Munsell color system: value, hue, and chroma. It is a coordinate system which can be viewed as a cylinder

• Value is also known as the gray scale and is the vertical, or z-axis. Value increases toward the high end (lighter) and decreases toward the low end (darker). Value is also expressed by the “lightness” factor, with varying levels of gray between the extremes of white and black. Teeth and other objects can be separated into lighter shades (higher value) and darker shades (lower value).
• Hue is the dominant color of an object, for example, red, green, or blue. This refers to the dominant wavelengths present in the spectral distribution. The continuum of these hues creates the three-dimensional (3-D) color solid.
• Chroma is the degree of saturation of a particular hue. For example, red can vary from “scarlet” to light pink, where scarlet has a high saturation and pink has a low saturation. The yellow color of a lemon is a more saturated, “vivid,” color than that of a banana, which is a less saturated, “dull” yellow. The colors in the center are dull (gray). In other words, the higher the chroma, the more intense the color.

Question 2

Metamerism

Answer 2

A phenomenon in which the color of an object under one type of light appears to change when illuminated by a different light source is known as metamerism.