초록 ▼

A method and apparatus are disclosed for detecting moving objects silhouetted against background clutter. A correlation subsystem 12 is used to register the background of a current image frame (framestore 1) with an image frame taken two time periods earlier (framestore 3). A first difference image

A method and apparatus are disclosed for detecting moving objects silhouetted against background clutter. A correlation subsystem 12 is used to register the background of a current image frame (framestore 1) with an image frame taken two time periods earlier (framestore 3). A first difference image is generated by subtracting the registered images, with the first difference image being filtered by low pass filter 34 and thresholded by a three level segmenter 36. A second difference image is likewise generated between the current image frame and another image frame taken at a different subsequent time period. This second difference image is likewise filtered and thresholded. The two difference images are logically ANDed together by gate 39 whose output is connected to a formatter, sorter and feature extractor 40. Track files are generated in CPU 16 for comparing subsequently extracted image features with previously stored extracted features.

대표청구항 ▼

A method of autonomously detecting flying aircraft in cluttered background, said method comprising: (a) taking a first frame of image data containing the aircraft from a sensor whose line of sight is generally normal to a component of a velocity vector of the aircraft, and storing the first image fr

A method of autonomously detecting flying aircraft in cluttered background, said method comprising: (a) taking a first frame of image data containing the aircraft from a sensor whose line of sight is generally normal to a component of a velocity vector of the aircraft, and storing the first image frame; (b) taking a second image frame by the sensor at a subsequent time and storing it; (c) taking a current image frame with the sensor and storing it; (d) using an area correlator to register the background clutter in the current and first image frames and subtracting the registered images to generate a first difference image; (e) low pass filtering the first difference image; (f) thresholding the first difference image so as to generate a first thresholded difference image in which pixels having amplitudes above a given threshold are mapped into a +1 state while pixels having amplitudes less than a negative threshold are mapped into a -1 state, with pixels between the two thresholds being mapped into a zero state; (g) performing steps d-f on the current image frame and the second image frame in lieu of the first image frame to generate a second thresholded difference image in place of the first thresholded difference image in said steps; (h) logically ANDing the first and second thresholded difference images to thereby generate a validated difference image; (i) extracting the features from the validated difference image and storing said features in a track file; (j) performing steps a-i on subsequent image frames and comparing subsequently extracted features with those stored in the track file whereby a given number of matches indicates that the moving aircraft has been detected.