Amazingly enough, the yellow looks quite natural, as do the rest of the color swatches. Again, adjust the brightness of the red projector so that the photometer indicates the same intensity as was measured with the blue. Adjust the brightness of the green projector so that the photometer indicates the same intensity as was measured with the blue. Turn on the blue projector and note the amount of blue light reflected by the yellow paper. Pick any swatch of color on the collage, say yellow, and aim the photometer at it. Having 'defined' white empirically in this manner, we can now move on to experiment with the collage. Now turn on all three projectors - the white paper will appear to be truly white and the other colors will look vibrant and realistic.

Turn off the blue light and turn on the green. With the photometer, measure and note the intensity of blue light reflected off the white sheet of paper. To show that that is indeed the case, illuminate the poster with just blue light. Since red, green, and blue provide a broad sampling of the visible spectrum, one would think that if the object reflects equal intensities of red, green, and blue light, it will appear white. Generally speaking, when we perceive an object as being white, we reason that the object must be reflecting all parts of the visible spectrum with equal intensities. A telescopic photometer 6 is used to measure the amount of light reflected off the piece of white paper. To that end, one would start with a different poster that has white, gray, and black paper on it (in addition to red, green, and blue). 5īefore performing the experiment on the collage, it might be instructive to first define what it means when an object appears 'white' in terms of what wavelengths of light are reflected. The poster is a collage of different colors of paper. Three independent brightness controls 4 adjust the light intensities so that illumination can be mixed in any ratio. Three projectors 2 with band-pass color filters 3 are set up to illuminate a 2'×3' poster with red, green, and blue light. 1 The present demonstration is a simplified re-creation of his experiment. Edwin Land dramatically demonstrated the phenomenon with his 'Color Mondrian' experiment and posited a retina/cortex system (retinex) explanation.

Unlike a spectro-photometer, which cannot categorize the color of objects, the eye has evolved to see the world in unchanging colors, regardless of unpredicatable illumination. What It ShowsĬolor is not actually a property of light or of objects that reflect light it is a sensation that arises in the brain. The experiment addresses questions like 'Does color inhere in the world, or in the eye?' It is a re-creation of Edwin Land's retinex theory experiment.

Edwin land jennifer land