US 6,147,710 AGranted

Method of correcting faults in an opto-mechanical scanning camera and a camera using the method

AssigneeThomson-CSF

InventorsJean-Marc Rouchon, Jean-Louis Ricci, Bernard Grancoin, Sylvie Vintezou, Gilles Dairon, Michel Jouan

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Abstract

An image output by a camera can contain a fault such that the signal output by the camera is not constant for a uniform background. To correct this fault, the method involves memorizing, as a correction image, a destructured image of the scene to be observed; this destructured image is generated by calculating the means of the signals obtained when the selected scene is observed while the camera settings are simultaneously modified inconsistently; the correction image is then subtracted from the image formed by the signals output by the detector during real observation of the scene selected with correct camera settings. Application to all scanning cameras.

Claims12

Dependent claims

A method of correcting, in a camera with a detector and opto-mechanical scanning, faults in the digital image of even- and odd-parity frames where the frames contain fixed points of the image arranged in lines and represented by digital values obtained by converting analog values output by the detector, comprising the steps of:

aiming the camera at a scene;
destructuring the image of the scene, for a given lapse of time, by making inconsistent changes to the camera settings including modifying the focus of the camera and modifying a direction of the camera line of sight;
acquiring, during the given lapse of time when the image of the scene is destructed, m, where m is a positive integer, frames with a same parity to calculate a mean frame in which each point within the mean frame has approximately the mean value of the digital values of corresponding points in the m frame;
memorizing a correction frame in which the value of each point corresponds to the value of corresponding points in the mean frame to within a given constant value;
adjusting the camera settings to correctly observe the scene;
and
subtracting, for each point in the correctly observed scene, the memorized value of the corresponding point from the correction frame.

4 more elements

Dependencies are inferred from the claim text.