The human eye is a powerful illuminant-adaptive trichromatic optical sensor. The phenomenon of colored shadows in twilight, described by Goethe and leading to a controversy among Newton and the community of physicists, shows the full circle of opponent and complementary colors adding to white. The colored shadows can be explained by von Laue interferences in the visible spectrum and diffractiveoptical cross-correlations between global and local information in the diffractiveoptical hardware of the human eye. They illustrate the most elementary—the spectral—transformations from physics into psychology in human vision. Scattering of global information in aperture space and diffraction of local information in image space of optical imaging systems leads to spectral/4D-spatio-temporal optical transformations into reciprocal grating space (Fourier/photoreceptor space) in the near field behind the retina. Three-dimensional (3D) grating-optical chromatic resonance—following von Laue’s equation—is governing adaptation to varying illuminants. The rebalancing of RGB diffraction orders toward a new white norm by shifting the chromatic resonance guarantees color constancy in human vision. At physically unbalanced stages in twilight the human eye “does not see what physically is real at a shadow area, but what the eye optically has calculated:” the hues of the colored shadows. The spectral transformations from physics into psychology, from the objective into the subjective world in vision, are based on wave/interference-optical transformations linking complementary and reciprocally interrelated worlds. Emil Wolf ’s prominent statements about the central role of von Laue’s equation in optics have largely encouraged research on these modern aspects of physiological diffractive-optical correlators.
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