User Guide

GNU Image Manipulation Program
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Deuteranopia (insensivity to green) With deuteranopia, the person has a deficiency in green vision. Deuteranopia is actually
like protanopia, because the person has a loss of red and green perception, but he has no luminance loss or hue shift.
Tritanopia (insensitivity to blue) With tritanopia, the person is deficient in blue and yellow perception, although he is still
sensitive to red and green. He lacks some perception of luminance, and the hues shift toward the long wavelengths.
Examples
Figure 14.53: Example of protanopia with some text
As you can see, a red-blind person cannot see the red (255,0,0) text on a black (0,0,0) background. You have to change the text
color. Daltonism occurs fairly frequently in the population.
Figure 14.54: Examples of the three types of vision deficiencies in one image
From top to bottom: normal vision, protanopia, deuteranopia, and tritanopia. It appears that the filters don’t give a fair reflection
of medical data. In deuteranopia, yellow is shifted toward red. In tritanopia, green is slightly represented in the blue range...