Device for correcting the faults of a sequence of images analyzed by an integrating matrix infrared sensor
First Claim
1. A device for correcting the faults of a sequence of images analyzed by an integrating matrix infra-red sensor, the cells constituting the sensor having differences of sensitivity, comprising:
- a first correction means for determining a first correction signal and for subtracting the first correction signal from a video signal given by the sensor, said first correction signal being variable as a function of the temperature of the background of the images, wherein said first correction means comprises;
means for determining a signal proportional to the mean luminance of at least one image preceding an image undergoing correction;
means for making an approximate determination of a signal proportional to the sensitivity of each cell of the sensor, for a given temperature, during a pre-calibration period, during which analyzed images represent a uniform background; and
means for obtaining a product of said signal proportional to the mean luminance and said signal proportional to the sensitivity of each cell, said product constituting the first correction signal;
said device for correcting faults further comprising a second correction means for determining a second correction signal and for subtracting said second correction signal from the video signal, wherein the second correction means is placed downstream of the first correction means, and the second correction signal is determined as a function of a first corrected video signal given by said first correction means, wherein the second correction means comprises;
means for storing values of the first corrected video signal during the course of a calibration period during which the analyzed images represent a uniform background; and
wherein the stored values are re-read periodically to constitute the second correction signal.
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Abstract
A device for correcting the faults of a sequence of images analyzed by an integrating matrix infrared sensor has a first part that determines a correction signal that is variable as a function of the temperature of the background of the images, equal to the product of a value representing the mean luminance of an image preceding the image undergoing correction, and a signal representing approximately the sensitivity of each cell of the sensor, constituted by the values of a video signal corresponding to an image analyzed in the course of a pre-calibration period; and a second part to determine a second correction signal, in storing the values of the first corrected video signal during a calibration period. An application of this device could be for the infrared cameras used in weapons systems.
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Citations
6 Claims
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1. A device for correcting the faults of a sequence of images analyzed by an integrating matrix infra-red sensor, the cells constituting the sensor having differences of sensitivity, comprising:
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a first correction means for determining a first correction signal and for subtracting the first correction signal from a video signal given by the sensor, said first correction signal being variable as a function of the temperature of the background of the images, wherein said first correction means comprises; means for determining a signal proportional to the mean luminance of at least one image preceding an image undergoing correction; means for making an approximate determination of a signal proportional to the sensitivity of each cell of the sensor, for a given temperature, during a pre-calibration period, during which analyzed images represent a uniform background; and means for obtaining a product of said signal proportional to the mean luminance and said signal proportional to the sensitivity of each cell, said product constituting the first correction signal; said device for correcting faults further comprising a second correction means for determining a second correction signal and for subtracting said second correction signal from the video signal, wherein the second correction means is placed downstream of the first correction means, and the second correction signal is determined as a function of a first corrected video signal given by said first correction means, wherein the second correction means comprises; means for storing values of the first corrected video signal during the course of a calibration period during which the analyzed images represent a uniform background; and wherein the stored values are re-read periodically to constitute the second correction signal. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification