Why were old 3D glasses almost always red and blue (and not, say, green and orange)?

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I know how old 3D glasses work, but I want to know why they were blue and red rather than two other colors opposite on the color wheel. My guess is that red and blue cellophane or inks were cheaper when the technology/technique was developed, but that’s only a guess. (I know how 3D glasses work and only want to know why those particular colors were popular or nearly universal.)

In: Technology
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The red and green cheat the RGB that you’re seeing by excentuating those two and not blue. Something like that.

Red and blue are on the opposite ends of the visible spectrum, green falls somewhere in the middle. The (comparatively) large frequency gap between those colours makes for better quality 3D images. Gives it more contrast I think, less colour overlap. Not an expert.

To understand this, you should understand how color works in your eyeball. You have 3 different color sensors in there called cones — these are cells that are stimulated by red, green, and blue wavelengths of light. Every color you see is some combination of your brain interpreting these 3 signals (yes brightness from rods is also in there if you want to get technical). A red filter basically blinds the red cones in one eye, and the blue filter blinds the blue cones in the other eye. What this does is make it so each eye is seeing a slightly different image. Your brain interprets this as the two images coming from different places, and is looks 3D. Ta-da!

Now, why not any other color on the color wheel? I’m going to do a bit of speculation and suggest that it is because red and blue block only those color receptors in your eye. An orange filter would block both red and green receptors, which wouldn’t be as effective at producing separate images for each eye. I suppose you could try red-green glasses, but then the effect would still not be as effective because the colors are not as far apart on the color graph as red and blue.

Check out the Physiology of Color section on the wiki here [wiki](https://en.wikipedia.org/wiki/Color_vision) for a graph.

Color TV has Red, Green, and Blue. The human eye has an extremely good sense for anything green, while both red and blue are a bit worse in their perception, but on the same level.

Green and orange would be a horrible idea. On one hand, you have a color that comes “pure” out of the screen and to which you are highly sensitive, on the other hand you’ve got a mix of all three TV colors, for which your sensitivity is lower. And, as you need green to mix this orange, the orange pic “bleeds” into the green one, too.

That’s why 3D glasses are blue and red: Primary colors on the TV to which your eyes are equally (low) sensitive.