Method and device for adapting a signal for the detection of the movement of an object

• US 7,136,842 B2
• Filed: 06/08/2001
• Issued: 11/14/2006
• Est. Priority Date: 02/24/2000
• Status: Active Grant

• Current Assignee: Image Processing Technologies, LLC (General Patent Corporation), William J. Brown
• Original Assignee: Holding B.E.V. S.A.
• Inventors: Pirim, Patrick
• Primary Examiner(s): Starks, Jr., Wilbert L.
• Application Number:
  US09/877,337
• Publication Number:
  US 20020156753A1
• Time in Patent Office: 1,985 Days
• Field of Search: 706/45, 704/230, 375/240
• US Class Current: 706/45
• CPC Class Codes: G06T 7/254 involving subtraction of images
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80
• CPC Class Codes: G06V 40/161 Detection; Localisation; Normalisation

Abstract

Systems and methods for adjusting a signal used for the detection of the movement of an object in a space represented by a set of data A_ij, associated with pixels forming a multidimensional space i, j, evolving with time, and represented at a succession of instants T, wherein the data are associated with the parameter A in the form of a digital signal DATA(A), composed of a sequence A_ijt of binary numbers of n bits associated with synchronization signals defining the instant T of the space, and the position i, j in this space, in which the signals A_ijt are received, in which the threshold and the gain in detection sensitivity of the parameter A are adapted.

The detection sensitivity of the parameter variation is also adapted.

Claims

1. A method of adjusting a signal used for the detection of a parameter carried by a signal, wherein the parameter is represented by a set of data A_ij, associated with pixels forming a multidimensional space i, j, evolving with time, and represented at a succession of instants T, wherein the data are associated with the parameter A in the form of a digital signal DATA(A), composed of a sequence A_ijt of binary numbers of n bits associated with synchronization signals defining the instant T of the space, and the position i, j, in the space, in which the signals A_ijt are received, the method comprising:

receiving the signal A_ijt from a signal amplifier;

comparing each value A_ijt with a smoothed value AI_ijt so as to determine the variation of the signal A_ijt at a given point in the space i, j, wherein AI_ijt is derived from the previous values of A_ijt in relation to a time constant CO_ijt;

generating a signal ABS_ijt=|A_ijt−

AI_ijt|;

generating binary threshold values DP_ijt of A_ijt in relation to a threshold S;

modifying the time constant values CO_ijt based on the corresponding overshoot threshold DP_ijt;

calculating histograms for ABS_ijt=|A_ijt−

AI_ijt|;

calculating histograms for A_ijt; and

adjusting the threshold S based on the calculated histograms of ABS so as to adjust the detection sensitivity of the variation of the parameter A; and

adjusting the gain of the amplifier based on the calculated histograms of A_ijt so as to adjust the amplitude of the received signal A_ijt.

2. The method according to claim 1, wherein DP_ijt is false if ABS_ijt is smaller than S, wherein DP_ijt is true if ABS_ijt is greater than S, wherein modifying includes calculating CO_ijt with respect to a previous value CI_ijt wherein

CO_ijt=CI_ijt+1 for DP_ijt false

CO_ijt=CI_ijt−

1 for DP_ijt true

wherein 0≦

CO_ijt≦

CO_Max, and wherein

CO_Max is a predetermined value.

3. The method according to claim 2, wherein an A.P.I. provides the predetermined CO_Max value.

4. The method according to claim 2, wherein a smoothed value AO_ijt is related to its previous value AI_ijt by the formula:

${\mathrm{AO}}_{\mathrm{ijt}}={\mathrm{A1}}_{\mathrm{ijt}}+\frac{A_{\mathrm{ijt}}-{\mathrm{A1}}_{\mathrm{ijt}}}{2^{{\mathrm{CO}}_{\mathrm{ijt}}}}.$

5. The method according to claim 2, wherein adaptation to the threshold is made with reference to a classification of the value ABS_ijt of ABS and to an overshoot ratio k.

6. The method according to claim 2, wherein the overshoot values of ABS_ijt are generated in relation to a plurality of thresholds S₀, S₁, S₂, S₃ each adjusted for a complete frame.

7. The method according to claim 1, wherein the parameter A is luminance.

8. The method according to claim 1, wherein the region of the space i, j affected is adjusted.

9. A device for adjusting a signal used for the detection of the movement of an object in a space represented by a set of data A_ij associated with pixels forming a multidimensional space i, j, evolving with time, and represented at a succession of instants T, wherein the data are associated with the parameter A in the form of a digital signal DATA(A), composed of a sequence A_ijt of binary numbers of n bits associated with synchronization signals defining the instant T of the space and the position i, j, in the space in which the signals A_ijt are received, the device comprising:

an amplifier that provides the signals A_ijt;

a processing unit including an input that receives the signals A_ijt from the amplifier, wherein the processing unit determines the values of a time constant CO_ijt and an overshoot value DP_ijt by comparing each value A_ijt with a smoothed value AI_ijt derived from previous values of A_ijt in relation to the time constant CO_ijt, wherein the comparison generates an overshoot value DP_ijt of A_ijt in relation to a threshold value, wherein CO_ijt is modified in relation to DP_ijt, and wherein the processing unit generates a sequence ABS_ijt=|A_ijt−

AI_ijt|;

a first histogram calculation unit that receives and processes the sequence A_ijt and controls the amplifier to adjust the amplitude of the parameter A; and

a second histogram calculation unit that receives and processes the sequence ABS_ijt and controls the threshold value used by the processing unit so as to adjust the detection sensitivity of the variation of the parameter A.

10. A device according to claim 9, further comprising a third histogram calculation unit that receives and processes the sequence A_ijt so as to adjust the region of the space i, j affected.

11. A device according to claim 9, further comprising a data input bus coupled to inputs of each histogram calculation unit and a classification bus coupling each histogram calculation unit to the other histogram units, wherein classification values generated by each histogram unit are provided to the other histogram calculation units over the classification bus.

12. The device according to claim 9, wherein the processing unit includes a memory for storing one or more threshold values.

13. The device according to claim 12, further including a multiplexer that determines, based on the received signal A, which of the one or more stored threshold values is used.

14. The device according to claim 9, wherein histogram calculation units are controlled by an A.P.I. software.