Optical image defocus correction
First Claim
Patent Images
1. Image scanning apparatus comprising:
- an image support;
a scanner for scanning an image on the image support, said scanner comprising an optical element for receiving optical image data from an image on the image support and a photoreceptor for receiving optical image data from the optical element and converting the optical data to an electrical data signal;
restoring means for providing a plurality of sets of image restoration data, each set of image restoration data representative of a different one of a plurality of defocus states of the optical element throughout an expected range of focal errors;
determining means for determining at least one defocus state of the scanner;
selecting means for selecting at least one of the sets of image restoration data provided by the restoring means based on the at least one defocus state determined by the determining means;
signal processing means for receiving the electrical data signal from the photoreceptor and the image restoration data from the selecting means and modifying the electrical data signal in accordance with the image restoration data received from the selecting means.
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Abstract
In an optical/electrical imaging system, optical depth of focus corrections are accomplished electronically. A plurality of defocus states of the optical system are measured and/or determined and image restoration coefficients corresponding to each of these states are stored. The state of defocus of the imaging system is then determined by deriving an image from a target having known characteristics, which are then correlated to determine a state of defocus. A microprocessor is utilized to provide appropriate defocus correction information to an electronic filter, thereby providing an adaptive filtering arrangement.
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Citations
18 Claims
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1. Image scanning apparatus comprising:
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an image support; a scanner for scanning an image on the image support, said scanner comprising an optical element for receiving optical image data from an image on the image support and a photoreceptor for receiving optical image data from the optical element and converting the optical data to an electrical data signal; restoring means for providing a plurality of sets of image restoration data, each set of image restoration data representative of a different one of a plurality of defocus states of the optical element throughout an expected range of focal errors; determining means for determining at least one defocus state of the scanner; selecting means for selecting at least one of the sets of image restoration data provided by the restoring means based on the at least one defocus state determined by the determining means; signal processing means for receiving the electrical data signal from the photoreceptor and the image restoration data from the selecting means and modifying the electrical data signal in accordance with the image restoration data received from the selecting means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for correcting defocus of an image scanner having an optical element for providing optical image information to a photoreceptor comprising the steps of:
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determining the focus characteristics of the optical element at a plurality of levels of defocus throughout an expected range of focal errors; converting the defocus characteristics of the optical element at each defocus level to a set of correction data and electronically providing the correction data; determining at least one defocus level of the scanner; selecting at least one set of correction data corresponding to the at least one defocus level determined in the defocus level determination step; and electronically correcting an electrical image signal from the photoreceptor in accordance with the correction data selected in the selecting step. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification