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Digital cameras come with lots of bells and whistles. But what matters most is picture quality, and it has improved significantly in the newest pixel takers. Instead of striking unexposed film, light entering a typical digital camera is focused onto a charge-coupled device, or CCD. This semiconductor array, consisting of many tiny picture elements (pixels), converts light energy into electron charge. A microprocessor reads the charge in each pixel as a digital signal and constructs an image of the scene.
CCDs and the human eye do not "see" light the same way, however. Creating authentic images depends on coherent focusing, color correction and proper whiteness. Aspherical lenses, which have nonspherical curvature, are inserted between the usual spherical lenses so light is focused uniformly on all pixels, improving sharpness. Filters in front of pixels ensure that color-processing algorithms can generate lifelike and bright colors. Other algorithms check for biases in the wavelengths of incoming light; these indicate the presence of fluorescent lighting, which gives a green cast, or tungsten (incandescent) lighting, which gives a yellow cast. The algorithms eliminate the tint, which the human brain does automatically, so a scene's true color and whiteness appear the way we expect them to appear.