US3769456A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and system for centroidal tv tracking
Assignee: Westinghouse Electric Corp
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Filing: 1972-01-21
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Granted: 1973-10-30
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Expires: 1992-01-21
Abstract
Abstract A mechanization employing digital techniques locates and tracks the centroid of an image produced by television (TV) scanning techniques. The TV video signal is processed for changes in level, corresponding to contrast differences between an image and background, and all level changes are stored digitally with coordinate information related to vertical and horizontal positions. Each level change is weighted as a function of displacement from the coordinate axes and summed each scan frame to yield the mean of all level changes recorded. The image as a target is tracked by sensing, digitally, the change of position of the image mean level-change, or centroid, in subsequent TV frames and providing positioning information to the TV camera tracking servomechanism so as to center the image on the TV display.
Inventors
- 👤 M Woolfson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:48
CPC Classifications
G; G01; G01S; G01S3/00; G01S3/78; G01S3/782; G01S3/785; G01S3/786; G01S3/7864
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
144 words
A method for tracking a target in accordance with defining the target centroid in a display thereof, comprising: defining a track window of a desired size for encompassing a target to be tracked, and including a corresponding predetermined number of quantum steps identified by the window coordinates and defining data cells, locating the track window in relation to the display coordinates to encompass the target, identifying transitions of the displayed target relative to the display background and assigning mass values to the window cells distinguishing those cells in which a transition is identified, weighting the cells having transition identifying mass values in accordance with their coordinate positions in the track window, effecting a summation of all such weighted cells separately for each coordinate and relative to the totality of weighted cells thereby to define the target centroid relative to the center of the window.
Claim 2
Independent Claim
144 words
A method for tracking a target in accordance with defining the target centroid in a display thereof, comprising: defining a track window of a desired size for encompassing a target to be tracked, and including a corresponding predetermined number of quantum steps identified by the window coordinates and defining data cells, locating the track window in relation to the display coordinates to encompass the target, identifying transitions of the displayed target relative to the display background and assigning mass values to the window cells distinguishing those cells in which a transition is identified, weighting the cells having transition identifying mass values in accordance with their coordinate positions in the track window, effecting a summation of all such weighted cells separately for each coordinate and relative to the totality of weighted cells thereby to define the target centroid relative to the center of the window.
Claim 3
Dependent Claim
19 words
The method of claim 1, further comprising adjusting the window size to a minimum consistent with encompassing the target.
Claim 4
Dependent Claim
63 words
The method of claim 1 wherein the step of identifying transitions comprises generating a video display signal corresponding to scanning of the target to be displayed in successive scan frames of horizontal, successive vertically displaced lines, and processing the video display signal and recognizing signal transitions therein as corresponding to transitions in the displayed target relative to backgound, for identifying the target transitions.
Claim 5
Dependent Claim
190 words
The method of claim 3 wherein the horizontal and vertical directions of scan correspond to the horizontal and vertical coordinates of the display and the track window and wherein quantum steps and hence cells in each coordinate are identified in accordance with the timing function of the scan in those corresponding directions, and wherein the identifying step further comprises detecting transitions in the video display signal during a horizontal line direction of scan for identifying horizontal transitions in the target and identifying the cell to which that horizontal transition is related in accordance with that time function, for the assignment of mass values identifying target transitions as to those cells, and comparing the video horizontal scan line signal for each horizontal line with the next preceding horizontal line in accordance with the corresponding quantum steps thereof, for each line in succession, to identify vertical transitions in any quantum step of that currently scanned horizontal scan line wherein there is a difference between the presence or absence of detected horizontal transitions as to the corresponding quantum step of the previous line, for assigning mass values to cells for identifying vertical transitions.
Claim 6
Dependent Claim
51 words
The method of claim 1, further comprising determining a total target displacement error value for each display coordinate as a combined function of a coarse error value of the track window position relative to the display coordinates and a fine error value of the target centroid relative to the window coordinates.
Claim 7
Dependent Claim
84 words
The method of claim 5 wherein the target is sensed by sensing means for producing the display of the target and further comprising: supplying the total target displacement error values to a positioning control means for said sensing means to center the target in the display, and responding to the gross error values generated by a target displacement during centering thereof in the display for displacing the track window to approach coincidence of the track window center, the display center, and the target centroid.
Claim 8
Dependent Claim
35 words
The method of claim 6 wherein locating of the track window is initially performed by manual positioning of either the track window or the image in the field of view by positioning the television camera.
Claim 9
Dependent Claim
113 words
The method as recited in claim 1 wherein the window includes a matrix of M cells and each cell includes a matrix of 2p predetermined quantum steps, where p 1, 2, 3, . . ., in each of the vertical (j) and horizontal (i) coordinate directions of the window, and said weighting step is performed for each transition in accordance with Vij (M/2) + 1 - i - (Vij/2p) Hij - (M/2) -1 + j + (hij/2p) for the vertical and horizontal coordinate weights, respectively, vij and hij defining the quantum step in the cell at which the transition is identified and each having a value of from 0 to 2p - 1.
Claim 10
Dependent Claim
14 words
The method of claim 8 wherein the summation step is performed in accordance with:
Claim 11
Dependent Claim
82 words
The method of claim 9, further comprising determining total target displacement error values in accordance with: EH EHF + EHC, and EV EVF + EVC where EHC - N/2 + k EVC + N/2 - r and wherein each of k and r are the centers of the track window in the horizontal and vertical coordinate directions, respectively, and range from position M/2 to position N - M/2 and N is the equivalent number of cells in each coordinate of the display.
Claim 12
Dependent Claim
59 words
The method of claim 1 wherein the window includes a matrix of M'' cells, each cell being defined by a single quantum step in each of the coordinates and wherein said weighting step for each of the vertical and horizontal transitions is performed in accordance with, respectively: Vij (M + 1/2) - i Hij - (M -1/2) + j.
Claim 13
Dependent Claim
14 words
The method of claim 11 wherein the summation step is performed in accordance with:
Claim 14
Dependent Claim
82 words
The method of claim 12, further comprising determining total target displacement error values in accordance with: EH EHF + EHC, and EV EVF + EVC where EHC - N''/2 + k EVC + N''/2 - r and wherein each of k and r are the centers of the track window in the horizontal and vertical coordinate directions, respectively, and range from position M''/2 to position N'' - M''/2, and N'' is the equivalent number of cells in each coordinate of the display.
Claim 15
Independent Claim
264 words
A system for tracking a target wherein the target is scanned in successive frames of horizontal, vertically displaced scan lines for producing a video signal affording a display thereof, and wherein a predetermined number of quantum steps are defined in each such line as a time function of the horizontal line scan rate, comprising: video signal processing means including a horizontal channel for detecting signal transitions corresponding to transitions between a target being scanned and background to define detected horizontal transitions in relation to the quantum steps in each line, a vertical channel including means for storing an indication of detected transitions in accordance with the quantum steps of a horizontal line and means for comparing the stored transition indications with detected transitions of a successive horizontal line in accordance with the corresponding quantum steps thereof to define detected vertical transitions in relation to the quantum steps in the successive horizontal line as to each quantum step wherein a difference comparison obtains, a track window generator for defining a track window as a function of a predetermined number of quantum steps in a horizontal line scan direction for a predetermined number of such horizontal scan lines contained within the scanning frame, means defining cells with said window as a function of said quantum steps of the window, means responsive to the detection of either a vertical or a horizontal transition by said processing means for assigning a target detection mass value to the corresponding cell, and means for computing from the assigned target detection mass values the centroid of the target in the display.
Claim 16
Independent Claim
264 words
A system for tracking a target wherein the target is scanned in successive frames of horizontal, vertically displaced scan lines for producing a video signal affording a display thereof, and wherein a predetermined number of quantum steps are defined in each such line as a time function of the horizontal line scan rate, comprising: video signal processing means including a horizontal channel for detecting signal transitions corresponding to transitions between a target being scanned and background to define detected horizontal transitions in relation to the quantum steps in each line, a vertical channel including means for storing an indication of detected transitions in accordance with the quantum steps of a horizontal line and means for comparing the stored transition indications with detected transitions of a successive horizontal line in accordance with the corresponding quantum steps thereof to define detected vertical transitions in relation to the quantum steps in the successive horizontal line as to each quantum step wherein a difference comparison obtains, a track window generator for defining a track window as a function of a predetermined number of quantum steps in a horizontal line scan direction for a predetermined number of such horizontal scan lines contained within the scanning frame, means defining cells with said window as a function of said quantum steps of the window, means responsive to the detection of either a vertical or a horizontal transition by said processing means for assigning a target detection mass value to the corresponding cell, and means for computing from the assigned target detection mass values the centroid of the target in the display.
Claim 17
Dependent Claim
45 words
A system as recited in claim 14 wherein said horizontal channel includes means for differentiating and fullwave rectifying the horizontal scan video signal to produce said transition signals, and threshold comparison means responsive to the transition signals to produce outputs identifying the detected target transitions.
Claim 18
Dependent Claim
107 words
A system as recited in claim 14 wherein said vertical channel includes means for digitizing the horizontal scan video signals at the quantum step rate and in accordance with amplitude levels thereof corresponding to and distinguishing scanning of a target versus scanning of background for all quantum steps of each line to provide digital signals for the quantum steps, and means for storing the digital values of a given horizontal scan line and comparing the digital values for the corresponding quantum steps of a successive scan line to identify vertical transitions at the quantum steps of the current scan line as to which a difference comparison obtains.
Claim 19
Dependent Claim
64 words
A system as recited in claim 14 wherein there is further provided means responsive to the computed centroid of the target in the display for producing error signals as a function of displacement of the target centroid from the center of the display, and an image positioning servomechanism responsive to the error signals from said computing means for centering the target in the display.
Claim 20
Dependent Claim
60 words
A system as recited in claim 17, further comprising means for manually locating the track window initially to encompass a target of the display, and said computing means includes means responsive to the error signals for supplying displacement signals to the track window generator for displacing the track window in the display in accordance with centering of the target therein.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-29 | 1977-04-30 | 1977-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-29 | 1981-04-30 | 1981-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-29 | 1985-04-30 | 1985-10-30 | $7700.00 | Window Closed / Lapsed |