Beyond 3-d

THOUGH QUITE INFORMA tive, Mr. Huntington’s piece contains a fundamental technical error in its explanation of anaglyphic stereography. It states that “in this system. … one [image] is projected through a red filter, making it invisible to the eye wearing the green lens, while the other is projected through a green filter, making it invisible to the eye wearing the red lens.” In fact the process works the opposite way. The red-on-white image is invisible to the eye looking through the red lens, and the red lens actually increases the contrast in the greenon-white image and makes it appear more or less black and white, and the green lens does the same for the red image.