Method and device for adapting a signal for the detection of the movement of an object
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.
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:
AO
ijt
=
A1
ijt
+
A
ijt
-
A1
ijt
2
CO
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 S 0 , S 1 , S 2 , S 3 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.