Color Vision

Color Vision

Write a short note on color perception.
Answer:

Perception of the color of an object is entirely a subjective experience, a result of a physiological response to physical stimulus. Color perception is described by three objectives of variables, i.e. hue, value, and chroma.

Hue of color perception:

• Hue describes the dominant color of an object, for example, Red, Green, Yellow, or Blue.
•  It represents the dominant wavelength present in the spectral distribution.
•  Red, green, and blue are the primary hues, while yellow, cyan, and magenta form the secondary hues.
• The primary hues are the colors that cannot be made by mixing other colors; hence, they are called primary colors. Secondary colors can be made by mixing two primary colors, for example, Mixing red and blue gives violet.

Value of color perception:

• Objects of the same color can be separated into lighter or darker shades.
• Value can be defined as the lightness or darkness of a color.
  It is also referred to as the grayscale value that can be measured independently of the hue.
• It is independent of the color.
• White color appears less white as the light intensity decreases. Hence it is said that the value of color decreases as it becomes darker.

Chroma of color perception:

• The degree of saturation of the hue is known as chroma.
• Chroma is a measurement of color intensity.
• For example, The yellow color of a lemon is less saturated than that of a sunflower.

Factors Influencing Color Perception:

Various factors interfere with the true perception of color, i.e. individual parameters such as fatigue of the eye due to repeated viewing of colors, low or high light levels, sex, and age; the surface of an object being viewed, and surrounding conditions.

• Repeated Viewing of Color Perception: Seeing the tooth for more than 5 seconds at a time should be avoided since this results in our eyes becoming accommodated to the red and yellow colors.
• Age and Sex of Color Perception: Our ability to perceive color and visual acuity is also affected by aging, chronic illnesses, glaucoma, and medications such as oral contraceptives, analgesics, antiepileptic drugs, and aspirin.

Surroundings of Color Perception:

• The perception of color is affected by interference from surrounding colors.
• Dark and bright clothing, lipstick, makeup, etc., will affect the selection of color and shade of teeth.
• Hence, patients should be instructed to wear light and neutral color clothing and avoid heavy makeup and dark lipsticks.
• When a patient is viewed in a room with intense colored walls, there is a tendency to select a hue that is complementary to the background color.
• Hence shade selection should be always performed in a room with neutral colors, preferably gray.
• At low light levels, the rods of the human eye are more dominant than the cones, and color perception is lost.
• At the same time, when the light is too bright, the color appears to change. This phenomenon is known as the Bezold-Brucke effect.