Tools‎ > ‎Digital Cameras‎ > ‎

Color Digital Images

A color digital image is made up of three layers 

of light measurement: RedGreen, and Blue.

Image of a landscape
The three primary colors

RGB images – look normal!

The layers of a digital image: The red, green, and blue images get compressed into a digital image
Red Layer Green Layer Blue Layer
Landscape with only red layer showing

Only the red color circle

Landscape with only green showing

Only the green color circle
Landscape with only blue layer showing

Only the blue color circle
Each layer represents the measured intensities of light of a particular color. For example, the green layer displays the intensities of green light measured at each pixel in the image. Dark colors or black indicate an absence of the color, and bright color represents large intensities.

The intensity of light measured by the camera depends on three factors:

  1. Does the object emit visible light? Objects that emit visible light are usually very hot–the sun, light bulbs, etc.
  2. If the object is not emitting light, then what is measured depends on the quality of light shining on the object. For example, at sunset, there is very little blue light remaining in the sunlight, so clouds become red and orange (depends on how much green light has been removed by atmospheric scattering).
  3. Position of the camera with respect to the source of light. Is the light shining through an object, so the camera is measuring the amount of colors that are passing through (transmitting through) the object. Otherwise, the camera is measuring the proportions of light reflected off the surface of the object.