Photos: Tenebraex tech for color blindness, night vision

Not all colors are created equal if a person's eye can't process them correctly. This page shows examples of how a weather map from the National Weather Service's Web site appears to people with varying color sight. The image at top left shows how the map appears to people with normal, or trichromatic, color vision.

The mildest and most common forms of color blindness both resulting in a red-green deficiency. People with one of those two forms, deutanomaly, for example, have anomalous green cones (a basic element of the eye) and would see the top-right map.

Someone with protanopia (a complete lack of red cones) would see the bottom left map, while someone with tritanopia (a complete lack of blue cones) would see the bottom right map. A person with total color blindness--a rare condition--would see the map in shades of black and white.