Speed and direction indicator for video systems

• US 3,890,462 A
• Filed: 04/17/1974
• Issued: 06/17/1975
• Est. Priority Date: 04/17/1974
• Status: Expired due to Term

• Current Assignee: John Arthur Murphy, John Ormond Limb
• Original Assignee: John Arthur Murphy, John Ormond Limb
• Inventors: Limb, John Ormond, Murphy, John Arthur
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Bookbinder, Marc E.
• Application Number:
  US05/461,586
• Time in Patent Office: 426 Days
• Field of Search: 178/DIG.20,DIG.1,DIG.21,DIG.33,DIG.22,DIG.36,6.8,DIG.38 179/2TV
• US Class Current: 348/135
• CPC Class Codes: G01S 11/12 using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 3/7864 T.V. type tracking systems
• CPC Class Codes: H04N 19/503 involving temporal prediction adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/523 with sub-pixel accuracy

Abstract

Apparatus is disclosed for measuring the speed and direction of subject movement between two video frames using only the video signal. Two selected differential signals are derived from the video signal. One of the differential signals is compared to a threshold to determine the presence of movement and the signs of the differential signals are compared to each other to find the direction of movement. Sums of each differential signal, in an area designated as moving, are accumulated over each video frame in accordance with the sign comparison between the two differential signals. At the end of each video frame, the sums are evaluated to ascertain the speed and to verify the direction of lateral movement. An embodiment of the invention uses this technique to measure only lateral subject movement. In another particularly advantageous embodiment, the same basic technique is extended to measure both horizontal and vertical movement. Individual signals indicative of horizontal and vertical movement are then combined to provide a resultant vectorial signal indicative of the complete subject movement that occurred.

Claims

1. In combination, a signal source for supplying successive frames of a video signal including a representation of a moving subject;

first comparing means connected to said signal source for supplying first and second differential signals derived by comparing picture element signals, said first differential signal indicative of the intensity difference between each picture element signal of the present video frame and a corresponding picture element signal of a previous video frame, said second differential signal indicative of the combination of the intensity differences between each picture element signal of the present video frame compared to a preceding picture element signal of the present video frame and the corresponding picture element signal in the previous video frame compared to a preceding picture element signal in the previous video frame;

storing means for accumulating first sums of said fIrst and second differential signals when subject movement between the present and previous video frames is in a first direction and second sums of said first and second differential signals when subject movement between the present and previous video frames is in a second direction opposite to said first direction;

evaluating means including second comparing means and first magnitude means, said second comparing means compares the first and second sums of said first differential signal to provide a directional signal indicative of the direction of movement, said first magnitude means providing a first magnitude signal proportional to the magnitude of said directional signal and also providing a second magnitude signal which is representative of an algebraic combination of at least the first and second sums of said second differential signal, said first magnitude means further comprising dividing means for providing a signal representative of a division of said first magnitude signal by said second magnitude signal to determine the speed of movement.

2. A combination according to claim 1 further including converting means coupled to said evaluating means for producing a combined translation signal indicative of the speed and direction of subject movement.

3. A combination according to claim 2 wherein said storing means comprises gating means for comparing the sign of said first differential signal to the sign of said second differential signal, said gating means producing a first level output indicative of said first and second differential signals having opposite signs to indicate motion in said first direction, and said gating means producing a second level output signal when said first and second differential signals have the same sign to indicate motion in said second direction whereby said first and second sums are accumulated from said first and second differential signals in accordance with the output of said gating means.

4. A combination according to claim 3 wherein said storing means further comprises first adding means connected to receive the magnitude of said first differential signal, second adding means conncected to receive the magnitude of said second differential signal, and separating means for comparing said first differential signal to a threshold to determine which of said first and second differential signals are indicative of motion, said separating means producing an output signal for said first and second adding means which respond by accumulating and storing sums of said first and second differential signals indicative of motion.

5. A combination according to claim 4 wherein said first adding means comprises first and second accumulating means and said second adding means comprises third and fourth accumulating means, said first and third accumulating means accumulating and storing the magnitudes of the differential signals applied thereto in response to a first level output signal from said gating means and the output signal from said separating means so as to provide said first sums indicative of subject movement in said first direction, and said second and fourth accumulating means accumulating and storing the magnitudes of the differential signals applied thereto in response to a second level output signal from said gating means and the output signal from said separating means so as to provide said second sums indicative of subject movement in said second direction.

6. A combination according to claim 5 wherein said storing means further comprises selecting means connected to receive the outputs of said gating means and said separating means and having a first output and a second output, said first output producing a predetermined signal level when said gating means produces the first level output and said separating means indicates said first and second differential signals are indicative of motion, and said second output producing another predetermined signal level when said gating means produces the second level output and said separating means indicates said first and second differential signals are indicative of motion whereby sums are accumulated of the magnitudes of said first differential signal indicative of opposite directions of motion and sums are accumulated of the magnitudes of said second differential signal indicative of opposite directions of motion.

7. A combination according to claim 6 including means for eliminating those portions of the accumulated sums of said first differential signal produced by subject motion in a direction perpendicular to said first direction between the present and previous video frames.

8. A combination according to claim 2 including generator means connected to said signal source for supplying a third differential signal indicative of the intensity difference between each current picture element signal compared to a corresponding picture element signal in a preceding video line, storing means for accumulating third sums of said first and third differential signals when movement between the present and previous video frames is in a third direction perpendicular to said first direction and fourth sums of said first and third differential signals when movement between the present and previous video frames is in a fourth direction opposite said third direction, further evaluating means including third comparing means and second magnitude means, said third comparing means compares the third and fourth sums of said first differential signal to provide an additional directional signal indicative of direction of movement in said third or fourth direction, said second magnitude means providing a third magnitude signal proportional to the magnitude of said additional directional signal and also providing a fourth magnitude signal which is representative of an algebraic combination of at least the third and fourth sums of said third differential signal, said second magnitude means further comprising dividing means for providing a signal representative of a division of said third magnitude signal by said fourth magnitude signal to determine the speed of movement in said third or fourth direction, and said converting means being further coupled to said further evaluating means so as to receive speed and direction indications of movement in said third or fourth direction to produce a translation vector signal indicative of the velocity of subject movement.

9. A combination according to claim 8 including means for eliminating those portions of the accumulated sums of said first differential signals associated with motion in said third or fourth directions motion which are produced by motion in said first or second directions between the present and previous video frames.