EP0543148B1 - Method and device for detecting changes in a video image - Google Patents
Method and device for detecting changes in a video image Download PDFInfo
- Publication number
- EP0543148B1 EP0543148B1 EP92117686A EP92117686A EP0543148B1 EP 0543148 B1 EP0543148 B1 EP 0543148B1 EP 92117686 A EP92117686 A EP 92117686A EP 92117686 A EP92117686 A EP 92117686A EP 0543148 B1 EP0543148 B1 EP 0543148B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- alarm
- brightness
- sections
- change
- quotient
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000000034 method Methods 0.000 title claims abstract description 18
- 238000001514 detection method Methods 0.000 claims abstract description 11
- 230000015572 biosynthetic process Effects 0.000 claims description 6
- 230000000007 visual effect Effects 0.000 claims description 2
- 230000006870 function Effects 0.000 claims 3
- 230000001629 suppression Effects 0.000 abstract description 5
- 230000001960 triggered effect Effects 0.000 description 7
- 238000011156 evaluation Methods 0.000 description 6
- 238000012935 Averaging Methods 0.000 description 4
- 238000011161 development Methods 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000001454 recorded image Methods 0.000 description 1
- 230000011664 signaling Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/18—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength
- G08B13/189—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems
- G08B13/194—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems
- G08B13/196—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems using television cameras
- G08B13/19602—Image analysis to detect motion of the intruder, e.g. by frame subtraction
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/18—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength
- G08B13/189—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems
- G08B13/194—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems
- G08B13/196—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using image scanning and comparing systems using television cameras
- G08B13/19639—Details of the system layout
- G08B13/19652—Systems using zones in a single scene defined for different treatment, e.g. outer zone gives pre-alarm, inner zone gives alarm
Definitions
- the invention relates to a method for detecting changes in the image content of video images and an arrangement for performing the method.
- Such methods and arrangements are used in video surveillance systems, which have the task of monitoring a certain area for changes, in particular for movements, and to output an alarm signal in the event of a detected change, false alarms being largely excluded.
- a system for detecting changes or movements in an area monitored by a television camera is known from the German laid-open specification DE 27 15 083 A1. There, movements or changes in the monitored area are recognized by discrimination of a video signal recorded by a television camera. To avoid false alarms due to general changes in brightness, the television picture obtained is divided into several fields, which are evaluated individually in an alarm device. One of these fields, which can be freely selected in size and position, is intended to suppress an alarm triggering by the evaluation result of one or more of the other fields if a change in brightness occurs in this field. Such a system largely avoids triggering a false alarm, but a false alarm is nevertheless triggered when the brightness changes, which covers almost the entire image area but not the selected field. Furthermore, in the event of an alarm-relevant change, the alarm is suppressed if a change in the selected field is detected at the same time.
- An image sensor system for the detection of changes is known from the European patent specification EP O 183 106 B1, in which a currently recorded image is compared with a plurality of stored images.
- the stored images contain normal changes, ie changes in the image content that should not trigger an alarm.
- This system a large number of changes that are not relevant to the alarm can be saved, thus reducing the likelihood of a false alarm being triggered, but with an increasing number of images to be compared, the processing time or the computing power required for the evaluation system also increases.
- alarm-relevant changes that are similar to non-alarm-relevant changes are not recognized or that general changes, for example certain changes in the lighting conditions in the monitored area, lead to false alarms if they do not match a stored image.
- An improvement in the evaluation reliability is achieved by dividing the recorded video image into a large number of fields, it being possible for one field to consist of only one pixel, depending on the complexity.
- a brightness value is determined integrally in each field and compared with the stored value of a corresponding field from a previous video image. If there is a change that exceeds a certain limit, it is assumed that an alarm-relevant object has entered.
- This evaluation also requires a limited adjustment to existing or changing lighting conditions given by comparing an integral mean value of video images recorded at a certain time interval and predetermined tolerance limits do not immediately trigger the alarm in the event of minor changes. In the case of rapid changes, for example as a result of passing clouds which cause shadowing, a false alarm is triggered in these known systems.
- a video intrusion detector is known from the essay "DAVID: ADVANCED DEVELOPMENTS FOR THE NEXT GENERATION OF VIDEO INTRUSION DETECTION" by E. Kozlow, Proceedings of the 1989 International Carnahan Conference on Security Technology, October 3, 1989, Zurich, pages 145-147. in which a target area to be monitored is divided into cells and a value for the intensity is formed for each cell. Intruders are recognized due to changes in contrast. Another document for intrusion detection is also specified in this document, in which intruders that only cause a small change in contrast are also detected. For this purpose, contrast differences of temporally successive images or cells are no longer assessed, but the ratio of the intensity in the target area and the average value of the background intensity is formed. The disadvantage of this method is that the ratio of the intensity in the target area to the average intensity in the background of the image can change during the course of the day due to a change in the position of the sun, which triggers false alarms.
- the object of the invention is to provide a video control system in which there is reliable suppression of false alarms and at the same time reliable detection of alarm-relevant changes.
- This object is achieved according to the invention in that, in the case of a currently recorded video image which is divided into a plurality of fields and in which a brightness value is determined integrally for each field, the quotient of this brightness value and the brightness value of the corresponding field from one
- the quotient is not 1, while the quotient is 1 if there is no change in brightness.
- the change in brightness is recognized as not relevant to the alarm if the quotients of the individual fields have the same value. If there are additional changes during a large-scale change in brightness due to alarm-relevant movements caused by an object or person entering the monitored area, the quotient in this or these fields differs from the others. So an alarm is triggered.
- the advantage of the method according to the invention is that an alarm-relevant change in the image content is recognized at all times.
- the difference between a current and a previous image is usually formed.
- a bright object then has, for example, a brightness value of 100, a dark object of 10. Due to a general change in the lighting conditions, for example, the brightness value of the bright object falls to 80, and that of the dark object accordingly to 8.
- the difference is formed, a value of 20 for the light and a value of 2 for the dark object.
- a difference value for an intruded, alarm-relevant object can be, for example, 10.
- alarm detection cannot take place without any doubt. Either a false alarm is accepted or the alarm is given interrupted when there is a large change in brightness, in the second case the alarm-relevant change does not lead to the alarm being given.
- a quotient of 1.25 results for both the light and the dark object, while a quotient which differs from this is obtained for an penetrated object, since an additional factor flows into the quotient formation due to the movement.
- An advantageous embodiment of the invention results from the specification of a limit range for the quotient from the current brightness value of a field and the corresponding brightness value of the field from a previous image. In this case, a change in brightness is only recognized when this limit range is exceeded or undershot. By specifying this limit range, possible false alarms are suppressed by small fluctuations in the image brightness, which do not affect all fields, or by image noise.
- color information is used to form the quotient. In this way it is achieved that alarm-relevant changes in the image content, which only affect the color, but not the brightness, are recognized.
- FIG. 1 shows an area to be monitored with buildings 1 and 2 and a vehicle 3.
- Vehicle 3 is assumed to be moving.
- the position of the vehicle in the current picture is shown by a dashed line
- the position in one previous picture is represented by the solid line.
- Quotient values are entered in the buildings, in the individual parts of the building, and in the vehicle. These values are, for example, 1.0 if the conditions remain the same or 1.4 if there is a general change in brightness between the current image and a previous image.
- the area in which there is a change due to the movement of the vehicle is shown hatched in the figure. In this area, a deviating quotient of, for example, 1.2 with otherwise constant conditions or 1.6 with a general change in brightness is determined. In both cases there is a quotient that differs from the rest of the picture, which indicates an alarm-relevant change and thus leads to the alarm being triggered.
- FIG. 2 shows an arrangement for carrying out the method according to the invention.
- This arrangement contains a surveillance camera 11, the video signal of which is fed to a functional unit for averaging 12 for the specific fields.
- the mean values obtained are passed to the functional unit for forming the quotient 15.
- Corresponding values of a previous image are also given from the memory 13 to the functional unit for forming the quotient 15.
- the quotients obtained are checked in the evaluation unit 16. The check concerns the comparison of the quotients obtained from the individual fields and recognizes deviations of quotients of one or fewer fields from the general average value which is formed from all fields of an image.
- a limit value of the deviation from the average value can be taken into account in the comparison, so that an alarm is not triggered when there are slight fluctuations that are not relevant to the alarm.
- the alarm signaling unit 17 is activated, which emits an acoustic and / or a visual alarm signal.
- the arrangement also contains a control unit 14, from which the sequence process is controlled. This control unit 14 is coupled to the other functional blocks; the individual connections are not shown in FIG. 2.
- the memory 13 is advantageously designed in such a way that the mean data of several previous images can be stored in it. In this way it is achieved that there is greater flexibility with regard to the selection of a previous image in the evaluation, in particular the time intervals of the images to be compared can be varied within certain limits.
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Computer Vision & Pattern Recognition (AREA)
- Closed-Circuit Television Systems (AREA)
- Apparatus For Radiation Diagnosis (AREA)
- Holo Graphy (AREA)
- Image Processing (AREA)
- Burglar Alarm Systems (AREA)
- Image Analysis (AREA)
Abstract
Description
Die Erfindung betrifft ein Verfahren zur Erkennung von Veränderungen des Bildinhaltes von Videobildern und eine Anordnung zur Durchführung des Verfahrens.The invention relates to a method for detecting changes in the image content of video images and an arrangement for performing the method.
Derartige Verfahren und Anordnungen werden in Videoüberwachungssystemen eingesetzt, die die Aufgabe haben ein bestimmtes Gebiet auf Veränderungen, insbesondere auf Bewegungen, hin zu überwachen, und im Fall einer erkannten Veränderung ein Alarmsignal auszugeben, wobei Fehlalarme weitgehend ausgeschlossen werden sollen.Such methods and arrangements are used in video surveillance systems, which have the task of monitoring a certain area for changes, in particular for movements, and to output an alarm signal in the event of a detected change, false alarms being largely excluded.
Ein System zum Erkennen von Veränderungen bzw. Bewegungen in einem von einer Fernsehkamera überwachten Gebiet ist aus der deutschen Offenlegungsschrift DE 27 15 083 A1 bekannt. Dort werden Bewegungen bzw. Veränderungen im überwachten Bereich durch Diskrimination eines von einer Fernsehkamera aufgenommenen Videosignales erkannt. Zur Vermeidung von Fehlalarmen durch allgemeine Helligkeitsänderungen wird das erhaltene Fernsehbild in mehrere Felder unterteilt, die einzeln in einer Alarmeinrichtung ausgewertet werden. Eines dieser in Größe und Lage frei wählbaren Felder ist dazu bestimmt, eine Alarmauslösung durch das Auswerteergebnis ein oder mehrerer der übrigen Felder zu unterdrücken, wenn eine Helligkeitsänderung in diesem Feld auftritt. Durch ein derartiges System wird zwar die Auslösung eines Fehlalarmes weitgehend vermieden, aber bei einer Helligkeitsänderung, die zwar nahezu den gesamten Bildbereich umfaßt, jedoch nicht das ausgewählte Feld, wird trotzdem ein Fehlalarm ausgelöst. Weiterhin wird im Fall einer alarmrelevanten Änderung die Alarmgabe unterdrückt, wenn gleichzeitig eine Veränderung im ausgewählten Feld erkannt wird.A system for detecting changes or movements in an area monitored by a television camera is known from the German laid-open specification DE 27 15 083 A1. There, movements or changes in the monitored area are recognized by discrimination of a video signal recorded by a television camera. To avoid false alarms due to general changes in brightness, the television picture obtained is divided into several fields, which are evaluated individually in an alarm device. One of these fields, which can be freely selected in size and position, is intended to suppress an alarm triggering by the evaluation result of one or more of the other fields if a change in brightness occurs in this field. Such a system largely avoids triggering a false alarm, but a false alarm is nevertheless triggered when the brightness changes, which covers almost the entire image area but not the selected field. Furthermore, in the event of an alarm-relevant change, the alarm is suppressed if a change in the selected field is detected at the same time.
Aus der europäischen Patentschrift EP O 183 106 B1 ist ein Bildsensorsystem zur Detektion von Änderungen bekannt, bei dem ein aktuell aufgenommenes Bild mit einer Mehrzahl von abgespeicherten Bildern verglichen wird. Die abgespeicherten Bilder beinhalten normale Änderungen, d.h. Änderungen des Bildinhalts, die keine Alarmauslösung hervorrufen sollen. Bei diesem System können zwar eine Vielzahl von nicht alarmrelevanten Änderungen abgespeichert werden und somit die Wahrscheinlichkeit einer Fehlalarmauslösung reduziert werden, aber mit zunehmender Anzahl der zu vergleichenden, abgespeicherten Bilder erhöht sich auch die Verarbeitungszeit bzw. die benötigte Rechenleistung des Auswertesystems. Ferner besteht die Möglichkeit, daß alarmrelevante Änderungen, die Ähnlichkeit mit nicht alarmrelevanten Änderungen haben, nicht erkannt werden oder allgemeine Änderungen, beispielsweise bestimmte Änderungen der Lichtverhältnisse im überwachten Gebiet, zu Fehlalarmen führen, wenn sie nicht mit einem abgespeicherten Bild übereinstimmen.An image sensor system for the detection of changes is known from the European patent specification EP O 183 106 B1, in which a currently recorded image is compared with a plurality of stored images. The stored images contain normal changes, ie changes in the image content that should not trigger an alarm. With this system, a large number of changes that are not relevant to the alarm can be saved, thus reducing the likelihood of a false alarm being triggered, but with an increasing number of images to be compared, the processing time or the computing power required for the evaluation system also increases. There is also the possibility that alarm-relevant changes that are similar to non-alarm-relevant changes are not recognized or that general changes, for example certain changes in the lighting conditions in the monitored area, lead to false alarms if they do not match a stored image.
Aus der deutschen Offenlegungsschrift DE 38 42 356 A1 ist ein System zum Feststellen einer Bewegung bzw. einer Veränderung im Überwachungsbereich mehrerer Fernsehkameras bekannt, bei dem jeweils das Bild einer Fernsehkamera analysiert wird, indem das aktuelle Bild mit einem vorangegangenen Bild verglichen wird. Dazu wird der Bildinhalt zeilenweise überprüft, wobei zu jeder Zeile ein Mittelwert aus Bildinformationen gebildet wird. Für alle Bildpunkte wird eine Sollabweichung von der jeweiligen Bildinformation vorgegeben und die Gesamtzahl der Bildpunkte des aktuellen Bildes, die die vorgegebene Sollabweichung überschreitet, wird mit der entsprechenden Gesamtzahl der Bildpunkte des gespeicherten Bildinhaltes verglichen und gegebenenfalls Alarm ausgelöst. Durch die zeilenweise Mittelwertbildung wird zwar in eingeschränktem Umfang eine Anpassung an wechselnde Lichtverhältnisse erreicht, jedoch führt die Mittelwertbildung auch zu Unsicherheiten bezüglich einer sicheren Erkennung von alarmrelevanten Veränderungen.From the German published patent application DE 38 42 356 A1 a system for determining a movement or a change in the surveillance area of several television cameras is known, in which the image of a television camera is analyzed in each case by comparing the current image with a previous image. For this purpose, the image content is checked line by line, with an average value being formed from image information for each line. A target deviation from the respective image information is specified for all pixels, and the total number of pixels of the current image that exceeds the specified target deviation is compared with the corresponding total number of pixels of the stored image content and an alarm is triggered if necessary. The line-by-line averaging adapts to changing lighting conditions to a limited extent, but the averaging also leads to uncertainties with regard to the reliable detection of alarm-relevant changes.
Eine Verbesserung in der Auswertesicherheit wird erreicht, indem das aufgenommene Videobild in eine Vielzahl von Feldern unterteilt wird, wobei je nach Aufwand ein Feld auch aus nur einem Bildpunkt bestehen kann. In jedem Feld wird ein Helligkeitswert integral bestimmt und mit dem gespeicherten Wert eines entsprechenden Feldes aus einem vorhergehenden Videobild verglichen. Liegt eine Veränderung vor, die einen bestimmten Grenzwert überschreitet, geht man davon aus, daß ein alarmrelevantes Objekt eingedrungen ist. Auch bei dieser Auswertung ist eine begrenzte Anpassung an bestehende bzw. sich verändernde Lichtverhältnisse gegeben, indem jeweils ein integraler Mittelwert von in gewissem Zeitabstand aufgenommenen Videobildern verglichen wird und vorgegebene Toleranzgrenzen bei kleineren Änderungen nicht unmittelbar zur Alarmauslösung führen. Bei schnellen Änderungen, beispielsweise durch vorüberziehende Wolken, die eine Schattenbildung verursachen, wird jedoch bei diesen bekannten Systemen ein Fehlalarm ausgelöst.An improvement in the evaluation reliability is achieved by dividing the recorded video image into a large number of fields, it being possible for one field to consist of only one pixel, depending on the complexity. A brightness value is determined integrally in each field and compared with the stored value of a corresponding field from a previous video image. If there is a change that exceeds a certain limit, it is assumed that an alarm-relevant object has entered. This evaluation also requires a limited adjustment to existing or changing lighting conditions given by comparing an integral mean value of video images recorded at a certain time interval and predetermined tolerance limits do not immediately trigger the alarm in the event of minor changes. In the case of rapid changes, for example as a result of passing clouds which cause shadowing, a false alarm is triggered in these known systems.
Eine Verbesserung in Bezug auf die Unterdrückung von Fehlalarmen ist gegeben, indem die Alarmgebung unterdrückt wird, wenn eine großflächige Änderung eintritt, d.h. wenn der überwiegende Anteil der ausgewerteten Felder eine Änderung erfährt, die über die Toleranzgrenzen hinaussgeht. In diesem Fall wird davon ausgegangen, daß sich die Lichtverhältnisse geändert haben. Durch diese Art der Alarmunterdrückung entsteht jedoch der Nachteil, daß während der Zeit der Alarmunterdrückung auch eine alarmrelevante Veränderung nicht erkannt werden kann.There is an improvement in the suppression of false alarms by suppressing the alarm when a large-scale change occurs, i.e. if the majority of the evaluated fields undergoes a change that goes beyond the tolerance limits. In this case it is assumed that the lighting conditions have changed. However, this type of alarm suppression has the disadvantage that an alarm-relevant change cannot be detected during the time of the alarm suppression.
Aus dem Aufsatz "DAVID: ADVANCED DEVELOPMENTS FOR THE NEXT GENERATION OF VIDEO INTRUSION DETECTION" von E. Kozlow, Proceedings of the 1989 International Carnahan Conference on Security Technology, 3. Oktober 1989, Zürich, Seiten 145-147, ist ein Videoeindringdetektor bekannt, bei dem ein zu überwachendes Zielgebiet in Zellen aufgeteilt wird und für jede Zelle ein Wert für die Intensität gebildet wird. Eindringlinge werden auf Grund von Kontraständerungen erkannt.
In diesem Dokument ist ferner einer weitere Methode zur Eindringdetektion angegeben, bei der auch Eindringlinge, die nur eine kleine Kontraständerung verursachen, erkannt werden. Zu diesem Zweck werden nicht mehr Kontrastunterschiede zeitlich aufeinanderfolgender Bilder oder Zellen bewertet, sondern es wird das Verhältnis der Intensität im Zielgebiet und dem Durchschnittswert der Hintergrundintensität gebildet. Der Nachteil dieser Methode besteht darin, daß sich im Tagesverlauf auf Grund eines veränderten Sonnenstandes das Verhältnis der Intensität im Zielgebiet und der durchschnittlichen Intensität im Bildhintergrund verändern kann, wodurch Fehlalarme ausgelöst werden.A video intrusion detector is known from the essay "DAVID: ADVANCED DEVELOPMENTS FOR THE NEXT GENERATION OF VIDEO INTRUSION DETECTION" by E. Kozlow, Proceedings of the 1989 International Carnahan Conference on Security Technology, October 3, 1989, Zurich, pages 145-147. in which a target area to be monitored is divided into cells and a value for the intensity is formed for each cell. Intruders are recognized due to changes in contrast.
Another document for intrusion detection is also specified in this document, in which intruders that only cause a small change in contrast are also detected. For this purpose, contrast differences of temporally successive images or cells are no longer assessed, but the ratio of the intensity in the target area and the average value of the background intensity is formed. The disadvantage of this method is that the ratio of the intensity in the target area to the average intensity in the background of the image can change during the course of the day due to a change in the position of the sun, which triggers false alarms.
Aufgabe der Erfindung ist es, ein Videokontrollsystem anzugeben, bei dem eine sichere Unterdrückung von Fehlalarmen und gleichzeitig eine sichere Erkennung von alarmrelevanten Veränderungen gegeben ist.The object of the invention is to provide a video control system in which there is reliable suppression of false alarms and at the same time reliable detection of alarm-relevant changes.
Diese Aufgabe wird gemäß der Erfindung gelöst, indem bei einem aktuell aufgenommenen Videobild, das in eine Vielzahl von Feldern unterteilt wird, und bei dem für jedes Feld ein Helligkeitswert integral bestimmt wird, der Quotient aus diesem Helligkeitswert und dem Helligkeitswert des entsprechenden Feldes aus einemThis object is achieved according to the invention in that, in the case of a currently recorded video image which is divided into a plurality of fields and in which a brightness value is determined integrally for each field, the quotient of this brightness value and the brightness value of the corresponding field from one
vorangegangenen Bild gebildet wird. Bei Vorliegen einer Helligkeitsänderung ist der Quotient ungleich 1, während der Quotient gleich 1 ist, wenn keine Helligkeitsänderung vorliegt.
Bei einer nicht alarmrelevanten Änderung, beispielsweise einer großflächigen Änderung der Lichtverhältnisse, wird die Helligkeitsänderung als nicht alarmrelevant erkannt, wenn die Quotienten der einzelnen Felder den gleichen Wert haben. Ergeben sich während einer großflächigen Helligkeitsänderung zusätzlich Änderungen auf Grund von alarmrelevanten Bewegungen durch einen in das überwachte Gebiet eindringenden Gegenstand oder eine eindringende Person, unterscheidet sich der Quotient in diesem oder diesen Feldern von den übrigen. Es wird also ein Alarm ausgelöst.previous picture is formed. If there is a change in brightness, the quotient is not 1, while the quotient is 1 if there is no change in brightness.
In the event of a change that is not relevant to the alarm, for example a large change in the lighting conditions, the change in brightness is recognized as not relevant to the alarm if the quotients of the individual fields have the same value. If there are additional changes during a large-scale change in brightness due to alarm-relevant movements caused by an object or person entering the monitored area, the quotient in this or these fields differs from the others. So an alarm is triggered.
Der Vorteil des erfindungsgemäßen Verfahrens liegt darin, daß zu jedem Zeitpunkt eine alarmrelevante Änderung im Bildinhalt erkannt wird. Bei den bekannten Verfahren wird meist die Differenz zwischen einem aktuellen und einem vorangegangenen Bild gebildet. Ein helles Objekt hat dann beispielsweise einen Helligkeitswert von 100, ein dunkles Objekt von 10. Durch eine allgemeine Änderung der Lichtverhältnisse fällt beispielsweise der Helligkeitswert des hellen Objektes auf 80, der des dunklen Objektes entsprechend auf 8. Bildet man die Differenz erhält man einen Wert von 20 für das helle und einen Wert von 2 für das dunkle Objekt. Ein Differenzwert für ein eingedrungenes, alarmrelevantes Objekt kann beispielsweise bei 10 liegen. Folglich kann eine Alarmerkennung nicht zweifelsfrei erfolgen. Entweder wird ein Fehlalarm in Kauf genommen oder die Alarmgabe bei einer großflächigen Helligkeitsänderung unterbrochen, wobei im zweiten Fall die alarmrelevante Änderung nicht zur Alarmgabe führt.The advantage of the method according to the invention is that an alarm-relevant change in the image content is recognized at all times. In the known methods, the difference between a current and a previous image is usually formed. A bright object then has, for example, a brightness value of 100, a dark object of 10. Due to a general change in the lighting conditions, for example, the brightness value of the bright object falls to 80, and that of the dark object accordingly to 8. If the difference is formed, a value of 20 for the light and a value of 2 for the dark object. A difference value for an intruded, alarm-relevant object can be, for example, 10. As a result, alarm detection cannot take place without any doubt. Either a false alarm is accepted or the alarm is given interrupted when there is a large change in brightness, in the second case the alarm-relevant change does not lead to the alarm being given.
Beim erfindungsgemäßen Verfahren ergibt sich sowohl für das helle als auch für das dunkle Objekt ein Quotient von 1.25, während sich für ein eingedrungenes Objekt ein dazu unterschiedlicher Quotient ergibt, da durch die Bewegung ein zusätzlicher Faktor in die Quotientenbildung mit einfließt.In the method according to the invention, a quotient of 1.25 results for both the light and the dark object, while a quotient which differs from this is obtained for an penetrated object, since an additional factor flows into the quotient formation due to the movement.
Eine vorteilhafte Ausgestaltung der Erfindung ergibt sich durch die Vorgabe eines Grenzbereiches für den Quotienten aus dem aktuellen Helligkeitswert eines Feldes und dem entsprechenden Helligkeitswert des Feldes aus einem vorhergehenden Bild. In diesem Fall wird eine Helligkeitsänderung erst dann erkannt, wenn dieser Grenzbereich über- oder unterschritten wird. Durch die Vorgabe dieses Grenzbereiches werden mögliche Fehlalarme durch kleinere Schwankungen in der Bildhelligkeit, die nicht alle Felder betreffen, oder durch Bildrauschen unterdrückt.An advantageous embodiment of the invention results from the specification of a limit range for the quotient from the current brightness value of a field and the corresponding brightness value of the field from a previous image. In this case, a change in brightness is only recognized when this limit range is exceeded or undershot. By specifying this limit range, possible false alarms are suppressed by small fluctuations in the image brightness, which do not affect all fields, or by image noise.
Eine vorteilhafte Weiterbildung ergibt sich auch durch die Bildung eines Mittelwertes aller unauffälligen Quotienten, von dem ausgehend ein Grenzbereich ermittelt wird, bei dessen Überschreiten eine relevante Änderung erkannt wird. Diese Mittelwertbildung ist insbesondere bei großflächigen Bildänderungen von Vorteil, da nicht in allen Feldern exakt die gleiche relative Änderung eintritt.An advantageous further development also results from the formation of an average value of all inconspicuous quotients, from which a limit range is determined, if a relevant change is detected when it is exceeded. This averaging is particularly advantageous in the case of large-area image changes, since not exactly the same relative change occurs in all fields.
In einer anderen vorteilhaften Weiterbildung der Erfindung werden mehrere Felder zu jeweils einem Bereich zusammengefaßt. Auf diese Weise entstehen mehrere Bereiche, von denen jeder für sich ausgewertet wird. Dementsprechend kann für jeden dieser Bereiche bei Vorliegen einer alarmrelevanten Änderung ein Alarmsignal ausgegeben werden, das diesem Bereich entspricht. Durch diese Zuordnung kann in vorteilhafter Weise das mit einer Videokamera überwachte Gebiet in mehrere Bereiche aufgeteilt werden, so daß bei einer Alarmgabe der Bereich, in dem eine alarmrelevante Änderung aufgetreten ist, erkennbar ist.In another advantageous development of the invention, several fields are combined into one area each. In this way, several areas are created, each of which is evaluated individually. Accordingly, an alarm signal corresponding to this area can be output for each of these areas when there is an alarm-relevant change. This assignment advantageously allows the area monitored by a video camera to be divided into several areas, so that when an alarm is given, the area in which an alarm-relevant change has occurred can be identified.
In einer weiteren Ausbildung der Erfindung werden anstelle der Helligkeitsinformation oder zusätzlich zur Helligkeitsinformation Farbinformationen zur Quotientenbildung herangezogen. Auf diese Weise wird erreicht, daß auch alarmrelevante Veränderungen des Bildinhaltes, die nur die Farbe, nicht aber die Helligkeit betreffen, erkannt werden.In a further embodiment of the invention, instead of the brightness information or in addition to the brightness information, color information is used to form the quotient. In this way it is achieved that alarm-relevant changes in the image content, which only affect the color, but not the brightness, are recognized.
Im weiteren wird die Erfindung an Hand der Figuren 1 und 2 näher beschrieben.
- Figur 1
- zeigt ein zu überwachendes Gebiet,
Figur 2- zeigt ein Ausführungsbeispiel der erfindungsgemäßen Vorrichtung.
- Figure 1
- shows an area to be monitored,
- Figure 2
- shows an embodiment of the device according to the invention.
In Figur 1 ist ein zu überwachendes Gebiet mit den Gebäuden 1 und 2, sowie einem Fahrzeug 3 dargestellt. Vom Fahrzeug 3 wird angenommen, daß es sich bewegt. Die Lage des Fahrzeugs im aktuellen Bild ist durch eine gestrichelte Linie dargestellt, die Lage in einem vorhergehenden Bild ist durch die durchgehende Linie dargestellt. In die Gebäude, sowie in den einzelnen Gebäudeteilen, und im Fahrzeug sind Quotientenwerte eingetragen. Diese Werte sind beispielsweise 1,0 bei gleichbleibenden Verhältnissen bzw. 1,4 bei bei einer allgemeinen Helligkeitsänderung zwischen dem aktuellen Bild und einem vorangegangenem Bild. Der Bereich, in dem sich durch die Bewegung des Fahrzeuges eine Veränderung ergibt, ist in der Figur schraffiert dargestellt. In diesem Bereich wird ein abweichender Quotient von beispielsweise 1,2 bei sonst gleichbleibenden Verhältnissen, bzw. von 1,6 bei einer allgemeinen Helligkeitsänderung ermittelt. In beiden Fällen ergibt sich ein vom übrigen Bild unterschiedlicher Quotient, der auf eine alarmrelevante Veränderung hinweist und somit zur Alarmauslösung führt.FIG. 1 shows an area to be monitored with
In Figur 2 ist eine Anordnung zur Durchführung des erfindungsgemäßen Verfahrens dargestellt. Diese Anordnung enthält eine Überwachungskamera 11, deren Videosignal an eine Funktionseinheit zur Mittelwertbildung 12 für die bestimmten Felder zugeführt wird. Die erhaltenen Mittelwerte werden an die Funktionseinheit zur Quotientenbildung 15 gegeben. Weiterhin werden entsprechende Werte eines vorangegangenen Bildes aus dem Speicher 13 an die Funktionseinheit zur Quotientenbildung 15 gegeben. Die erhaltenen Quotienten werden in der Auswerteeinheit 16 überprüft. Die Überprüfung betrifft den Vergleich der von den einzelnen Feldern erhaltenen Quotienten und erkennt Abweichungen von Quotienten eines oder weniger Felder vom allgemeinen Durchschnittswert, der aus allen Feldern eines Bildes gebildet wird. Weiterhin kann bei dem Vergleich ein Grenzwert der Abweichung vom Durchschnittswert berücksichtigt werden, so daß eine Alarmauslösung bei geringfügigen Schwankungen, die nicht alarmrelevant sind, nicht stattfindet. Im Falle einer Abweichung über den Grenzwert hinaus wird die Alarmgabeeinheit 17 angesteuert, die ein akustisches und/oder ein visuelles Alarmsignal ausgibt. Die Anordnung enthält weiterhin eine Steuereinheit 14, von der der Ablaufvorgang gesteuert wird. Diese Steuereinheit 14 ist mit den übrigen Funktionsblöcken gekoppelt, die einzelnen Verbindungen sind in der Figur 2 nicht dargestellt.FIG. 2 shows an arrangement for carrying out the method according to the invention. This arrangement contains a
Der Speicher 13 ist in vorteilhafter Weise so ausgeführt, daß in ihm die Mittelwertdaten mehrerer vorangegangener Bilder gespeichert werden können. Auf diese Weise wird erreicht, daß bei der Auswertung eine größere Flexibilität bezüglich der Wahl eines vorangegangenen Bildes gegeben ist, insbesondere können die Zeitabstände der zu vergleichenden Bilder innerhalb bestimmter Grenzen variiert werden.The
Claims (8)
- A method of detecting changes in the image content of video images wherein the video image is subdivided into a plurality of sections, for each section the brightness value is integrally defined, the brightness value is compared with the brightness value of the corresponding section of a preceding video image, and as a function of the comparison result changes in the image content are determined, where an alarm is given when an alarm-relevant change is detected,
characterised in that- for the detection of alarm-relevant changes a quotient is formed from the current brightness value and the corresponding preceding brightness value of each section,- a non-alarm-relevant, large-area change in brightness is detected when the quotient in most of the sections changes but retains the same value and- in the event of a large-area change in brightness an alarm-relevant change is detected when, in one or more of the sections within the large-area change in brightness, a value of the quotient which differs from the other sections is determined. - A method as claimed in Claim 1, characterised in that for the quotients of the values of the change in brightness of corresponding sections of a preceding image and a current image, a critical range is predetermined, on the overshooting of which a change in the image content is detected.
- A method as claimed in Claim 1 or 2, characterised in that- in the event of a large-area change, a mean quotient is calculated,- commencing from this mean value, a critical range is determined and- an alarm-relevant change is detected when this critical range is overshot in one or more sections.
- A method as claimed in one or more of Claims 1 to 3, characterised in that one or more sections are combined to form a zone and on the detection of an alarm-relevant change in a zone an alarm signal assigned to this zone is emitted.
- A method as claimed in one or more of Claims 1 to 4, characterised in that in place of the brightness information, colour signals are determined and used for the quotient formation.
- A method as claimed in one or more of Claims 1 to 5, characterised in that in addition to the brightness information, colour information is used for the quotient formation.
- A device for the implementation of the method for the detection of changes in the image content of video images, wherein the video image is subdivided into a plurality of sections, as claimed in one or more of Claims 1 to 6,
characterised by- a surveillance camera (11)- a function unit (12) for the mean value formation of the brightness- or colour information in each of the defined sections- a memory (13) for the storage of mean value data- a function unit (15) for the formation of the quotient of mean values of corresponding sections of a current image and the mean values, stored in the memory (13), of a preceding image,- an analysis unit (16) for the analysis of the obtained quotients, where the quotients obtained in the individual sections are compared and in the event of a deviation of one or more sections from the general average value, an alarm-relevant change is detected,- an alarm unit (17) for the acoustic and/or visual emission of an alarm signal on the detection of an alarm-relevant change and- a control unit (14) for the flow control. - A device as claimed in Claim 7, characterised in that the memory (13) is designed such that the mean value data of a plurality of images can be stored.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4138254A DE4138254C1 (en) | 1991-11-21 | 1991-11-21 | |
| DE4138254 | 1991-11-21 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0543148A1 EP0543148A1 (en) | 1993-05-26 |
| EP0543148B1 true EP0543148B1 (en) | 1996-03-27 |
Family
ID=6445258
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP92117686A Expired - Lifetime EP0543148B1 (en) | 1991-11-21 | 1992-10-16 | Method and device for detecting changes in a video image |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0543148B1 (en) |
| AT (1) | ATE136141T1 (en) |
| DE (2) | DE4138254C1 (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4407528C2 (en) * | 1994-03-07 | 1998-04-09 | Sq Services Ag | Motion detectors and motion detection methods |
| DE19614675C2 (en) * | 1995-04-27 | 1998-05-14 | Alfred Frauhammer | Hazard detection system with video surveillance |
| DE19603766A1 (en) * | 1996-02-02 | 1997-08-07 | Christian Gieselmann | Intruder movement detection for surveillance and alarm system |
| DE19603935A1 (en) * | 1996-02-03 | 1997-08-07 | Bosch Gmbh Robert | Movement detection within a surveillance area |
| DE19749136C2 (en) * | 1997-11-06 | 2000-01-27 | Geutebrueck Gmbh | Method and device for detecting movements |
| EP0939386A1 (en) * | 1998-02-28 | 1999-09-01 | Siemens Building Technologies AG | Space surveillance device |
| DK0939387T3 (en) * | 1998-02-28 | 2004-02-02 | Siemens Building Tech Ag | Room monitoring device |
| US7196720B2 (en) | 1998-03-06 | 2007-03-27 | Intel Corporation | Method and apparatus for powering on an electronic device with a video camera that detects motion |
| US6801246B2 (en) | 2001-02-27 | 2004-10-05 | Thomson Licensing, S.A. | Method and apparatus for detecting change in video source material |
| DE10206871A1 (en) * | 2002-02-18 | 2003-09-04 | Vidair Ag | Method and device for testing a fire detection device |
| DE10261501A1 (en) * | 2002-12-23 | 2004-07-15 | Mobotix Ag | Data reduction procedures |
| JP3849645B2 (en) * | 2003-01-20 | 2006-11-22 | ソニー株式会社 | Monitoring device |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2715083C3 (en) * | 1977-04-04 | 1983-02-24 | Robert Bosch Gmbh, 7000 Stuttgart | System for the discrimination of a video signal |
| CA1116286A (en) * | 1979-02-20 | 1982-01-12 | Control Data Canada, Ltd. | Perimeter surveillance system |
| US4679077A (en) * | 1984-11-10 | 1987-07-07 | Matsushita Electric Works, Ltd. | Visual Image sensor system |
| DE3842356A1 (en) * | 1988-12-16 | 1990-06-28 | Martin Spies | System for detecting a movement or a change in the surveillance area of a number of television cameras |
-
1991
- 1991-11-21 DE DE4138254A patent/DE4138254C1/de not_active Expired - Fee Related
-
1992
- 1992-10-16 DE DE59205839T patent/DE59205839D1/en not_active Expired - Lifetime
- 1992-10-16 EP EP92117686A patent/EP0543148B1/en not_active Expired - Lifetime
- 1992-10-16 AT AT92117686T patent/ATE136141T1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| ATE136141T1 (en) | 1996-04-15 |
| DE4138254C1 (en) | 1993-06-24 |
| DE59205839D1 (en) | 1996-05-02 |
| EP0543148A1 (en) | 1993-05-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| DE3634628C2 (en) | ||
| DE69815977T2 (en) | AGAINST GLOBAL CHANGES IN NON-SENSITIVE VIDEO MOTION DETECTOR | |
| DE60132622T2 (en) | METHOD AND DEVICE FOR SELECTING THE BEST VIDEO IMAGE FOR TRANSMISSION TO A REMOTE SITE WITHIN A CLOSED TELEVISION SYSTEM FOR RESIDENTIAL AREA SAFETY MONITORING | |
| EP0543148B1 (en) | Method and device for detecting changes in a video image | |
| EP0853299B2 (en) | Method and device for actuating a door assembly in response to the presence of persons | |
| EP0939387B1 (en) | Room supervision device | |
| DE4430016C2 (en) | Motion detectors and a method for motion detection | |
| DE60006411T2 (en) | counting | |
| DE102013019138A1 (en) | A method for detecting a hidden state of a camera, camera system and motor vehicle | |
| DE2617112A1 (en) | SYSTEM FOR DETECTING MOVEMENT IN THE SURVEILLANCE AREA OF A TELEVISION CAMERA | |
| EP1531342B1 (en) | Method of detecting pedestrians | |
| DE4343095C2 (en) | Method and circuit for eliminating interference signals from video signals | |
| DE3214254C2 (en) | ||
| EP0445334A1 (en) | Method of intruder detection | |
| DE69010062T2 (en) | TV motion detector with false alarm immunity. | |
| DE3842356A1 (en) | System for detecting a movement or a change in the surveillance area of a number of television cameras | |
| DE112021005703T5 (en) | INFORMATION PROCESSING EQUIPMENT AND INFORMATION PROCESSING PROCEDURES | |
| EP1026632B1 (en) | image-evaluation system and method | |
| DE69814809T2 (en) | Image processing method with spatio-temporal noise filter steps and device for performing the method | |
| DE60319346T2 (en) | SENSOR WITH DETECTION OF COVERS | |
| DE69014840T2 (en) | Digital circuit for checking a movement. | |
| EP1485889B1 (en) | Method for following at least one object in a scene | |
| DE69229831T2 (en) | IMAGE ANALYZER | |
| DE19744694B4 (en) | Video motion detection device | |
| DE19641000A1 (en) | Individual identification method for security access system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
| AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT CH DE ES FR GB IT LI |
|
| 17P | Request for examination filed |
Effective date: 19930730 |
|
| 17Q | First examination report despatched |
Effective date: 19940727 |
|
| RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: GRUNDIG E.M.V. ELEKTRO-MECHANISCHE VERSUCHSANSTALT |
|
| GRAH | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOS IGRA |
|
| GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
| AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): AT CH DE ES FR GB IT LI |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: ES Free format text: THE PATENT HAS BEEN ANNULLED BY A DECISION OF A NATIONAL AUTHORITY Effective date: 19960327 |
|
| REF | Corresponds to: |
Ref document number: 136141 Country of ref document: AT Date of ref document: 19960415 Kind code of ref document: T |
|
| REF | Corresponds to: |
Ref document number: 59205839 Country of ref document: DE Date of ref document: 19960502 |
|
| ET | Fr: translation filed | ||
| GBT | Gb: translation of ep patent filed (gb section 77(6)(a)/1977) |
Effective date: 19960430 |
|
| ITF | It: translation for a ep patent filed | ||
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: AT Effective date: 19961016 |
|
| PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
| STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
| 26N | No opposition filed | ||
| REG | Reference to a national code |
Ref country code: GB Ref legal event code: 732E |
|
| REG | Reference to a national code |
Ref country code: FR Ref legal event code: TP |
|
| REG | Reference to a national code |
Ref country code: GB Ref legal event code: IF02 |
|
| REG | Reference to a national code |
Ref country code: FR Ref legal event code: TP |
|
| REG | Reference to a national code |
Ref country code: CH Ref legal event code: EP Ref country code: CH Ref legal event code: PUE Owner name: PLETTAC AG; KOEBBINGHAUSER HAMMER; 58840 PLETTENBERG (DE) Free format text: FORMER OWNER: GRUNDIG E.M.V. ELEKTRO- MECHANISCHE VERSUCHSANSTALT MAX GRUNDIG GMBH & CO. KG: Ref country code: CH Ref legal event code: NV Representative=s name: BOVARD AG PATENTANWAELTE Ref country code: CH Ref legal event code: PUE Owner name: FUNKWERK PLETTAC ELECTRONIC GMBH; WUERZBURGER STRASSE 150; 90766 FUERTH (DE) Free format text: PLETTAC AG#KOEBBINGHAUSER HAMMER#58840 PLETTENBERG (DE) -TRANSFER %%- FUNKWERK PLETTAC ELECTRONIC GMBH#WUERZBURGER STRASSE 150#90766 FUERTH (DE) |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 20091007 Year of fee payment: 18 Ref country code: CH Payment date: 20091027 Year of fee payment: 18 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 20091117 Year of fee payment: 18 Ref country code: IT Payment date: 20091023 Year of fee payment: 18 Ref country code: GB Payment date: 20091026 Year of fee payment: 18 |
|
| REG | Reference to a national code |
Ref country code: CH Ref legal event code: PFA Owner name: FUNKWERK PLETTAC ELECTRONIC GMBH Free format text: FUNKWERK PLETTAC ELECTRONIC GMBH#WUERZBURGER STRASSE 150#90766 FUERTH (DE) -TRANSFER TO- FUNKWERK PLETTAC ELECTRONIC GMBH#WUERZBURGER STRASSE 150#90766 FUERTH (DE) |
|
| REG | Reference to a national code |
Ref country code: CH Ref legal event code: PL |
|
| GBPC | Gb: european patent ceased through non-payment of renewal fee |
Effective date: 20101016 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: CH Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20101031 Ref country code: FR Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20101102 Ref country code: LI Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20101031 |
|
| REG | Reference to a national code |
Ref country code: FR Ref legal event code: ST Effective date: 20110630 |
|
| REG | Reference to a national code |
Ref country code: DE Ref legal event code: R119 Ref document number: 59205839 Country of ref document: DE Effective date: 20110502 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: GB Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20101016 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: IT Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20101016 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20110502 |