The red filter, the loss-90 percent, only 200 lumens of red light.

经红色滤光片后，光损失90%，只剩下200流明的红光。

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You have to put a deep red filter on the lens to increase the contrast.

你还需要在镜头上加一块深红色的滤光镜来提高反差。

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They photographed a Scottish tartan ribbon three times, once with a red filter, once with green, and once with blue.

FORBES: GPotD: Maxwell's Tartan Ribbon

Then they developed the pictures and loaded them onto three different projectors, one with a red filter over the lens, one with green, and one with blue.

FORBES: GPotD: Maxwell's Tartan Ribbon

Instead of having spectacles with a crude red filter for one eye and green for the other, the Real D system relies on circularly polarised light with one lens polarising the light to the left, and the other to the right.

ECONOMIST: Animation takes on a whole new reality