• Background
  • Instructions
  • Illustration


Dichromats have only two working cone systems. Thus, they can see colors, though a much lesser range of colors than do trichromats. There are three major forms of dichromats, which include protanopes, deuteranopes, and tritanopes, missing the long, middle, and short wavelength cones, respectively. Dichromats require only two colored lights to match any monochromatic light as compared to trichromats, who require three. Dichromats see in color but cannot make some of the discriminations that are easy for trichromats. Protanopia and deuteranopia are linked to the X-chromosome and are therefore inheritable and more common in men than women. Protanopia and deuteranopia are also more common than Tritanopia.

Since dichromats have a different, and in this case reduced, set of cones, they will experience colors differently. In this illustration, you can simulate how different pictures look to people with different forms of dichromacy. You can choose images from a preselected set or choose one of your own.


First, every effort has been made to make these simulated images as accurate as possible; it is impossible to make them completely accurate. The transformations follow as closely as possible how the eye actually sees the colors of these images. Second, these simulations are performed in real time. They are computationally intensive and might take some seconds do perform. It will depend upon the browser you use and the power of your device; however, this illustration has been successfully run on tablets and phones.


Full Screen Mode

To see the illustration in full screen, which is recommended, press the Full Screen button, which appears at the top of the page.

Illustration Tab


Below is a list of the ways that you can alter the illustration. The settings include the following:

Choose Missing Cone: Select which cone will be missing. None restores all cones. The right-hand image will be labeled with the type of dichromacy present or with "Trichromat" if all cones are present.
Choose a Preselected Image: Choose another image to examine from a preselected list.
Use Your Own Image: You can upload your own image.


Pressing this button restores the settings to their default values but does not change the image.