US 4,364,089 A · Binary correlation video tracker

Abstract

A binary correlation video tracker and a video preprocessor included therein, which function cooperatively to form binary patterns of values for the picture elements (pixels) in a predetermined pixel array of each of a plurality of frames of video gray level information generated by an electro-optical sensor, is disclosed. Histograms are formed for selected pixel arrays in the predetermined array of a video frame in accordance with a set of predetermined gray level values. The formed histograms are combined in accordance with a discriminant function to form a composite histogram from which at least one gray level value of the set is selected. Those pixels of the predetermined array which have gray level values corresponding to the selected at least one gray level value are assigned one of two predetermined values, the other pixels being assigned the other of the two predetermined values, whereby a binary pattern of values for the predetermined pixel array is formed. Accordingly, the video tracker selects a reference binary pattern of pixels from the formed binary pattern of the predetermined pixel array of one video frame. The selected reference binary pattern is used for performing auto and cross-correlation operations in the video tracker in accordance with a binary correlation coefficient function. In the cross-correlations, another reference binary pattern of pixels and position thereof in the predetermined array is derived for each of the video frames generated subsequent the one video frame, the results being used in the computation of tracking errors in the video tracker. In the auto correlations, a maximum autocorrelation value is derived for use in determining when the reference binary pattern may be updated with the another reference binary pattern for further binary correlation processing.

Claims12

Dependent claims

A video preprocessor for forming a binary pattern of gray level values for the picture elements (pixels) in a predetermined array of a frame of video gray level information generated from an electrical sensor, said preprocessor comprising:

means for distributing the pixels of one selected pixel array within said predetermined pixel array of said video frame into a first gray level histogram based on a predetermined set of gray level values;
means for distributing the pixels of at least one other selected pixel array within said predetermined pixel array of said video frame into a second gray level histogram based on said predetermined set of gray level values;
means for selecting at least one gray level value of said predetermined set based on a discriminant function of said first and second gray level histogram distributions;
and
means for assigning one of two predetermined values to those pixels in said predetermined pixel array of said video frame which have a selected gray level value and for assigning the other of said two predetermined values to those pixels in said predetermined pixel array of said video frame which have an unselected gray level value, whereby a binary pattern of gray level values are formed for the pixels in the predetermined pixel array of said video frame.

2 more elements

A binary correlation video tracker including an electro-optical sensor for generating sequentially a plurality of frames of video gray level information of its field-of-view, an optical system operative to guide the line-of-sight of a predetermined target image to within the field-of-view of said sensor, and a tracking servo means, governed by at least one tracking error, to control the guidance of said optical system, said binary correlation video tracker further comprising:

means for forming a binary pattern of values for the picture elements (pixels) in a predetermined pixel array of each of said plurality of frames of video gray level information generated by said sensor, said forming means further including:
means for distributing the pixels of one selected pixel array within said predetermined pixel array of each of said video frames into corresponding first gray level histograms based on a predetermined set of gray level values;
means for distributing the pixels of at least one other selected pixel array within said predetermined pixel array of each of said frames into corresponding second gray level histograms based on said predetermined set of gray level values;
means for selecting at least one gray level value of said predetermined set for each frame of video gray level information based on a discriminant function of the respectively corresponding first and second gray level histogram distributions;
and
means for assigning one of two predetermined values to selected pixels in said predetermined pixel array of each of said video frames said selected pixels having a selected gray level value corresponding to the video frame in which they are contained;
and for assigning the other of said two predetermined values to the unselected pixels in said predetermined pixel array of each of said video frames;
means for selecting a reference subarray binary pattern of pixels from the predetermined pixel array of one frame of video gray level information;
means for correlating the formed binary pattern of said reference subarray with the formed binary patterns of the predetermined pixel arrays of generated video frames subsequent said one frame based on a binary correlation coefficient function;
and
means for generating said at least one tracking error based on the results of said binary pattern correlations of said correlating means.

8 more elements

Dependencies are inferred from the claim text.

Binary correlation video tracker

Life of this patent

Binary correlation video tracker

Life of this patent

Abstract

Claims12