Trichromatic TheoryThere are only two forces in the world, the sword and the spirit. In the long run, the sword will always be conquered by the spirit. - Napoleon Bonaparte
spc Bd 1 Bd 3
Share This Page

Trichromatic Theory

The eye is made up of four different types of light sensing cells:

  • rods for black and white and

  • cones for roughly red, green and blue (long, medium and short wavelengths)

This theory was developed by Thomas Young and Hermann von Helmholtz after having people adjust the intensity of a number of different colored light sources to reproduce a specified color. Young and Helmholtz saw that three different colored lights (color primaries) were required to match any color they could specify.


After Images Not Explained?

Some color researchers suggest that, although trichromatic theory is useful, it doesn't answer all color phenomena, afterimages, for example.


Stare at the red dot until the image goes away.

See an image that is not really there in this optical illusion.


As you stare at the dot, fatigue of the retinal process occurs. When the image disappears, you see the complimentary colors.


We Think After Images Are Explained

We, however, believe that the trichromatic theory does provide an explanation for after images.

It is well known that a nerve that has fired requires additional time to recharge and fire again. What is less well known, or easily forgotten, is that the cones seem to adjust to various brightnesses over time and will fire periodically regardless of the level of light. (Have you ever see colors in the dark?)

After looking at a particular color for a period of time, that color cone is tired and fires less frequently then the other cones which have not been firing.


Opponent Process Theory

Although our eyes see color according to the trichromatic theory, our brain kicks in and uses the opponent process theory. It examines the relative strength of the cones using opponent pairs in this pattern:

  • red vs. green

  • blue vs. yellow

  • light vs. dark  or  black vs. white (brightness)

Read more about the opponent process theory.

Home Facts and Fiction Resolution Color and Eyesight    Benhams Disk    Chromatic Adaptation    Chromostereopsis    Color Blindness    Color Discrimination    Color Sensitivity    Gender Differences    Metamerism    Trichromatic Theory Eye Color Peripheral Vision Blind Spot Night Vision Aging Effects Hold Time Timing

3D Stereograms

See 3d Pictures that just jump off the page. Stereograms are fun and enjoyable.
3D Stereograms
Send Us Your Comments The Site Map Link To Our Site Tell A Friend About Us Related Links Report A Broken Link Contact Information

Are you planning a cruise vacation? How about an Arctic cruise, a South America cruise, a Panama cruise, a Mediterranean cruise, a Caribbean cruise, a Hawaiian cruise, an Alaska cruise, a windjammer cruise or a Boston harbor cruise?

Shop at our toy store for all kinds of toys. We have children's toys, diecast toys, board games, logic games, paper dolls, cartoon dolls, dinosaur toys, shark toys, plush stuffed animals and much more.

See us for virtual web hosting. We do multiple domain hosting, web hosting business to business.


The information published here is for entertainment purposes only and is in no way intended to dispense medical opinion or advice or to be a substitute for professional medical care, be it advice, diagnosis or treatment, by a medical practitioner. If you feel ill or if you have a medical issue, you should consult a health care professional.

Site Map | Terms of Use | Privacy & Security | Contact Us | Purchase Agreement | Send Feedback
Vision and The Science of Seeing
© 1996-2005 by All Rights Reserved.