How do coloured filters work in 3D glasses?

Three dimensional (3D) effects are seen when the left eye and right eye view a scene from slightly different angles. The brain can be fooled into seeing the same if each eye is shown a slightly different image. The two images are projected on a screen in complementary colours. Glasses with matching filters ensure that each eye only sees one image. Complementary pairs of colours include red and green, red and blue, blue and green, red and cyan, green and magenta or blue and yellow.