Method and apparatus for pixel non-uniformity correction
First Claim
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1. An apparatus for correcting a plurality of picture element values from an image sensing array using at least two correction signals comprising:
- means for forming an image data signal from a plurality of picture element values;
means for forming at least two correction signals from at least two correction values for each picture element of said image sensing array;
first lookup table means having at least one input for receiving at least one correction signal and at least one additional input for receiving said image data signal for performing a first function on each picture element value of said image data signal in accordance with the value of one of the correction signals corresponding to said picture element of said image sensing array; and
second lookup table means having at least one input for receiving at least one correction signal and at least one additional input for receiving said image data signal for sequentially performing a second function on each picture element value that has had the first function applied so as to provide a plurality of corrected picture element values.
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Abstract
An apparatus for reading and correcting an image including: a sensor which receives light and converts it to electrical signals; a digitizing unit to convert the analog image signal to a digital signal; a calibration unit to capture calibration data for each pixel under known illumination conditions and to produce individual correction values for each pixel and a correction unit comprised of a look-up table addressed by both the digital image signal and the correction values which corrects the digital image data.
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Citations
12 Claims
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1. An apparatus for correcting a plurality of picture element values from an image sensing array using at least two correction signals comprising:
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means for forming an image data signal from a plurality of picture element values; means for forming at least two correction signals from at least two correction values for each picture element of said image sensing array; first lookup table means having at least one input for receiving at least one correction signal and at least one additional input for receiving said image data signal for performing a first function on each picture element value of said image data signal in accordance with the value of one of the correction signals corresponding to said picture element of said image sensing array; and second lookup table means having at least one input for receiving at least one correction signal and at least one additional input for receiving said image data signal for sequentially performing a second function on each picture element value that has had the first function applied so as to provide a plurality of corrected picture element values.
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2. An apparatus for correcting the output signal levels from an image sensing means incorporating an array of photosensitive elements comprising:
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means for creating an illumination image beam; at least one array of photosensitive elements positioned to receive the illumination image beam, each photosensitive element providing as an output a signal level that is a function of the illumination impinging thereon; means for converting the output signal levels from each of said photosensitive elements into digital signal values; means for determining a multiplicity of differing photosensitive element correction values corresponding to a multiplicity of different photosensitive elements of said array; means for storing each of said photosensitive element correction values; means for controlling said stored photosensitive element correction value storage means and said array of photosensitive elements to concurrently provide the digital values of the output signal levels from the photosensitive elements and the corresponding correction values for said photosensitive elements; and means for correcting the output signal levels from said array of photosensitive elements incorporating a digital memory which is addressed using both the digital values of said output signal levels from the photosensitive elements and said correction values from said means for storing. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for correcting the output signal levels from an image sensing means incorporating an array of photosensitive elements comprising:
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means for creating an illumination image beam; at least one array of photosensitive elements positioned to receive the illumination image beam, each photosensitive element providing as an output a signal level that is a function of the illumination impinging thereon; means for converting the output signal levels from each of said photosensitive elements into digital signal values; means for creating at least three different calibration exposure levels for said array of photosensitive elements; and means for calculating digital correction look-up tables for a plurality of the photosensitive elements of said array based on the digital signal values created during said calibration exposures. - View Dependent Claims (11, 12)
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Specification