| 摘要 |
Method and apparatus for measuring the quality and sharpness of images and for using the measurement results to control parameters such as camera and projector focusing, range finding, optical system modifications and the like. In one embodiment, an image is formed on a medium which has an electrical property that varies predictably with the sharpness of an image incident on it. The property is measured and the derived electrical signal controls automatic focusing of objective and projection lenses, range finder settings, and the like. The invention relies on the discovery of an interaction between images, strain waves and electrical properties in certain devices which allows deriving an electrical signal whose magnitude corresponds to high spatial frequency Fourier components of the image. In addition to other useful characteristics, the electrical signal is at a maximum when the overall sharpness of the image is high and drops off significantly as the image becomes blurred. Alternately, high frequency components of the spatial Fourier transform of images are found by other means, e.g., optically, and the magnitude of these components is used as an indication of the sharpness of the images, and of other parameters of optical systems.
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