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          Video screens display colors by illuminating pixels with varying strengths of red, green, and blue signals.  Since people with the most common forms of color blindness have difficulty detecting small differences between the amount of red and green in a signal, ColorblindTV uses technology to magnify this difference.

          Although one could increase this red-green difference by adding more red throughout the image, that would make the greens look yellow, the yellows orange, and the whites and blues would look reddish.  A similar problem would occur by adding more green throughout the image.  Increasing both the red and the green throughout the image would not increase the red-green difference, and would just add a brownish tint to the entire image. 

          The solution is to alter only the colors where there is a red-green difference (leave the blues and yellows and whites alone) by using the amount of this difference to make the adjustments.  In this way, reds are made redder, greens are made greener, and many colors are left unchanged.  This is accomplished by the use of a difference amplifier to measure the red-green signal difference at each moment, and then controlling how much of that difference signal is added back to the original red and green signals.