Hughes Aircraft Company

Other

Hughes Electronics Corporation

Kenneth E Prager

Stephen J Herbst

Gillian K Groves

Jerry N Sisneros

John J Wootan

Douglas M Gleichman

Kim M Chacon

Robby Mauri

An automated system and method for testing a sensor by evaluating the output thereof with respect to a known target. The advantageous method includes the step of acquiring an output signal from the sensor in response to a known target, said output including signature signal S, random noise N.sub.R and fixed pattern noise N.sub.FP. Next, the sensor output signal is processed to provide a first signal which includes essentially signature signal S and fixed pattern noise N.sub.FP, a second signal which includes essentially random noise N.sub.R and a third signal which includes essentially fixed pattern noise N.sub.FP. The third signal is adaptively filtered to provide a filtered signal fixed pattern noise signal N'.sub.FP. The filtered signal N'.sub.FP is subtracted from the first signal to extract a signature S. In a particular embodiment, the signature is processed to acquire a modulation transfer function and a signal peak baseline therefrom. The modulation transfer function, signal peak baseline and random noise signals are processed to acquire a minimum resolvable temperature of said sensor.

Automated system for testing an imaging sensor

A method for measuring and quantifying clutter, and target detection and tracking systems that employs wavelet-based clutter quantification to generate a clutter number and a signal-to-clutter ratio derived therefrom to achieve improved target detection performance. The method processes video signals representative of an image scene containing a target and background clutter to provide for more accurate tracking of the target by a tracker(s). The method comprises processing the video signals to compute a wavelet clutter number, processing the video signals to compute a signal-to clutter ratio using the wavelet clutter number, and generating a pointer to a lookup table that sets parameters and selects the tracker that is to be used to track the target based upon the computed signal-to clutter ratio.

Image-based detection and tracking system and processing method

A scene based nonuniformity correction method (40) that computes and applies offset correction errors to a video signal corresponding to an image derived from a imaging sensor (11). A video signal derived from the sensor (11) is processed such that a vector representing offset correction terms is formed, and this vector is initially set to zero. Each element in this vector represents a correction term for a particular detector of the sensor (11). The vector is applied to each pixel of the image by a processor (13) as the pixels are read from the sensor (11). To measure the offset error, the image is separated into vertically oriented regions, each comprising a plurality of channels. The average of each channel within a region is computed (42), and a set of region vectors is foraged, such that there is one region vector for each region. Each region vector is then globally high-pass filtered and then edges larger than a predefined threshold are detected (43), and marked (44). Then, each region vector is further separated into sub-regions (45). The isolated sub-regions are locally high-pass filtered. In one embodiment, the correction terms for each vertical region vector are averaged together, resulting in a single correction vector (48). The correction terms calculated for each vertical region may also be applied individually to each detector of the sensor (11). In this second embodiment, the offset level error in each region for each channel is calculated (49), wherein the offset level error at boundary edges is undefined. The correction terms corresponding to a region are applied as the detector (11) scans the scene and views a portion corresponding to that particular region. The correction terms are smoothed at region boundaries to eliminate noise due to boundary transitions.

Nonuniformity correction of an imaging sensor using region-based

An imaging system including a scanning linear detector array is calibrated with the aid of a source of radiation to provide uniformity in gain among the various detectors of the array. A first memory is provided for storing a map of the source obtained by a scanning through a succession of parallel line scans by means of a single one of the detectors, the detector array being offset between the successive line scans to enable the single detector to perform all of the line scans. A second memory is provided to store an image of the source provided by a scanning by all of the detectors along their respective scan lines. The data obtained in each line scan in each of the memories is averaged. Then, the average value for a scan line stored in the second memory is divided by the average value of the same scan line appearing in the first memory to provide a ratio for each scan line. The ratio is the gain of the detector of the scan line relative to the gain of the first detector. The mapping allows equalization of the gains for eliminating the effect of nonuniformities of the test source from the resultant calculation of the relative detector gains.

Measurement of relative detector gain

Techniques for calibrating differential temperature sources including the use of a calibrated infrared imaging sensor having an associated calibrated temperature function that is expressed as a function of a predetermined calculated parameter indicative of the actual differential temperature of a differential temperature source. The temperature source being calibrated is thermally imaged at different indicated differential temperatures to provide thermal images associated with the indicated temperatures, and such images are processed to define the calculated parameter as as function of indicated temperature. The calculated parameter function is substituted in the calibrated temperature function to provide a calibrated temperature function that is expressed as a function of indicated differential temperature.

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Los Angeles, CA, United States of America

Kenneth E Prager