JP2022188988A - Information processing device, information processing method, and program - Google Patents

Abstract

To suppress a situation in which a subject is not detected, when an event-based sensor is used.SOLUTION: An information processing device acquires an address event signal indicating the position and time of a pixel at which a change in luminance occurs. The information processing device includes detection means for detecting a subject on the basis of the address event signal, and generation means for generating a stimulus that can be sensed by the subject when the time period that the subject is not detected is longer than a predetermined time period.SELECTED DRAWING: Figure 4

Description

The present invention relates to subject detection using event-based sensors.

2. Description of the Related Art An event-based sensor that outputs changes in luminance of each pixel in real time as an address event signal is known (see Patent Document 1).

JP 2019-134271 A

The problem to be solved by the present invention is to suppress situations in which a subject is not detected when using an event-based sensor.

An information processing apparatus according to the present invention for solving the above-described problems is an information processing apparatus that acquires an address event signal indicating the position and time of a pixel at which a change in luminance occurs, wherein the address event signal is used to determine whether a subject is and generating means for generating a stimulus that can be sensed by the subject when the subject is not detected for a period longer than a predetermined time.

According to the present invention, when an event-based sensor is used, situations in which the subject is not detected can be suppressed.

Block diagram showing a hardware configuration example of an information processing device Block diagram showing a functional configuration example of an information processing device Diagram showing a configuration example of an event-based sensor Flowchart for explaining processing executed by an information processing device

An information processing apparatus according to an embodiment of the present invention will be described below with reference to the drawings. At that time, the same numerals are attached to the parts having the same function in all the drawings, and the repeated description thereof will be omitted.

In the event-based sensor disclosed in Patent Document 1, the detection sensitivity to address events is controlled by controlling the time width of a dead zone with respect to changes in luminance according to the detection frequency of address events. However, when the event-based sensor disclosed in Patent Document 1 is used for high-speed detection of a specific subject, the following problems occur. If the detection sensitivity for the address event is lowered (the width of the dead zone is narrowed), the luminance change will not be detected, and the subject detection accuracy will be lowered. On the other hand, increasing the detection sensitivity for address events (widening the width of the dead zone) will detect changes in luminance caused by random noise such as photon shot noise, in addition to changes in subject luminance. Accuracy will decrease.

<Embodiment 1>
<Information processing device: Fig. 1>
FIG. 1 shows an information processing apparatus according to this embodiment. In FIG. 1 , an information processing apparatus 100 includes an imaging optical system 1010 , an imaging unit 101 (event-based camera) including a photoelectric conversion element 1011 , a CPU 102 , a memory 103 , a display unit 104 and an operation unit 105 . The imaging unit 101 is a sensor using a photoelectric conversion element 1011 that outputs an address event signal according to received incident light. The imaging unit 101 detects a luminance change for each pixel as an event, and the address event signal indicates the position and time of the pixel where the luminance change occurs. The imaging optical system 1010 is specifically a light receiving lens, receives incident light, and forms an image on the photoelectric conversion element 1011 . The CPU 102 reads out and executes the OS and other programs stored in the memory 103, controls each connected component, and performs calculations of various processes, logical judgments, and the like. The processing executed by the CPU 102 includes information processing according to the present embodiment. Further, the CPU 102 controls focus driving and aperture driving of the imaging optical system 1010, driving of the photoelectric conversion element 1011, and the like. The memory 103 is, for example, a hard disk drive or an external storage device, and stores programs and various data related to information processing according to the embodiment. The display unit 104 outputs the calculation results and the like of the information processing apparatus 100 to the display device according to instructions from the CPU 102 . The display device may be of any type, such as a liquid crystal display device, a projector, or an LED indicator. The operation unit 105 is, for example, a touch panel, a keyboard, a mouse, or a robot controller, and is a user interface that receives input instructions from the user. Note that the information processing apparatus 100 may have mechanisms other than the hardware configuration listed here.

<Functional Configuration Example of Information Processing Device: FIG. 2>
Next, a functional configuration example of the information processing apparatus according to this embodiment will be described with reference to FIG. The information processing apparatus 100 includes an imaging unit 101 , a detection unit 201 , a stimulus control unit 202 that controls a stimulus perceivable by a subject, and an image processing unit 203 . Further, the information processing device 100 is connected to an output device 200 capable of outputting stimuli generated by the stimulus control section 202 . The information processing device 100 may have the function of the output device 200 . It should be noted that the information processing apparatus according to the present embodiment may include at least the detection unit 201 and the stimulus control unit 202, but may have other functions. Here, an outline of each function will be explained. The information processing device 100 performs various information processing based on the output of the photoelectric conversion element 1011 that outputs an address event signal corresponding to the received incident light. A detection unit 201 detects a subject within the shooting angle of view based on the address event signal. As an example, assuming here that the event-based sensor captures a fixed angle of view, a moving object within the captured angle of view is detected as a subject. Conversely, when the shooting parameters are fixed and there is no moving object, the detection unit 202 does not detect anything because the address event signal is small. A detailed description of the detection unit 201 will be given later. The stimulus control unit 202 generates a stimulus that can be perceived by the subject and controls the output device 200 to output the stimulus. Details of stimulation and its control will be described later. Based on the address event signal, the image processing unit 203 generates an image in which a predetermined pixel value corresponding to the direction of change in brightness is assigned to the position of the pixel where the change in brightness occurs.

<Event-based sensor: Fig. 3>
An example of an event-based sensor according to this embodiment will be described. The event-based sensor counts the number of photons incident on each pixel and determines the timing when the counted number of photons exceeds a predetermined threshold. The event-based sensor also measures the time required (the number of clocks) until the number of photons reaches or exceeds the first threshold, and detects changes in luminance by comparing the required times. Specifically, when the previously measured required time is T0 and the latest required time is T, if the difference T−T0 is equal to or greater than the second threshold value, a change in luminance in the negative direction is detected. If the difference T0-T is greater than or equal to the second threshold, a positive luminance change is detected. If the difference between T and T0 is less than the second threshold, no change in brightness is detected. Note that the second threshold is a value equal to or greater than zero, and uses a preset value or a value set according to other parameters.

A detailed configuration will be described below. FIG. 3a is a diagram showing a configuration example of the photoelectric conversion element 1011. FIG. A photoelectric conversion element 1011 is composed of a pixel portion 110 and a peripheral circuit 120 . The peripheral circuit 120 has a vertical arbitration circuit 121 and a horizontal readout circuit 122 .

FIG. 3b is a diagram showing a configuration example of each pixel section that constitutes the event-based sensor. The pixel section 110 includes a photoelectric conversion section 111 , a pixel counter 112 , a time counter 113 , a first determination circuit 114 , a memory 115 , a comparator 116 , a second determination circuit 117 , a response circuit 118 and a selection circuit 119 . The photoelectric conversion unit 111 includes an avalanche photodiode (SPAD) that operates in Geiger mode, and is configured such that the number of photons incident on the photoelectric conversion unit 111 is counted by a pixel counter 112 . The time counter 113 counts the time for the photon to enter the photoelectric conversion unit 111 . By configuring an event-based sensor using SPAD, it is possible to detect luminance changes at the single-photon level. By detecting a single-photon level luminance change, an address event signal can be acquired even in a dark vision state such as at night.

When the number of photons counted by the pixel counter 112 reaches the first threshold, the time counter 113 stops counting time by the first determination circuit 114 . The memory 115 stores past count values of the time counter 113 , and the comparator 116 is used to calculate the difference count value between the current count value of the time counter 113 and the past count value of the time counter 113 . demand.

The second determination circuit 117 sends a request signal to the vertical arbitration circuit 121 via the response circuit 118 when the difference count value is greater than or equal to the second threshold. The response circuit 118 receives a response from the vertical arbitration circuit 121 indicating permission or non-permission to output the address event data. If the difference count value is less than the second threshold, no request signal is sent.

When response circuit 118 receives a response indicating permission to output, selection circuit 119 outputs the count value of time counter circuit 113 to horizontal output circuit 122 . The horizontal output circuit 122 outputs the received count value from the photoelectric conversion element 1011 to the detection unit 201 as an output signal.

Since the count value of the difference calculated by the comparator 116 corresponds to the reciprocal of the incident frequency of photons, the photoelectric conversion element 1011 according to the present embodiment measures "change in incident frequency of photons", that is, changes in luminance. It has the function to In addition, using the second determination circuit 117, an address event is output only when the difference between the time intervals at which the number of incident photons reaches the first threshold is greater than or equal to the second threshold. That is, the photoelectric conversion element outputs the incident frequency when the difference in incident frequency is equal to or greater than the second threshold, and does not output the incident frequency when the difference is less than the threshold. With the above configuration, it is possible to realize an asynchronous photoelectric conversion element that detects a change in brightness as an address event in real time for each pixel address.

<Variation of photoelectric conversion element>
In the above description, the case of using a photoelectric conversion element that detects a change in the incidence frequency of photons by measuring the time at which photons are incident using a SPAD in the photoelectric conversion unit has been described. However, if the photoelectric conversion element is an asynchronous photoelectric conversion element that detects a change in brightness as an address event in real time, the configuration shown in FIG. 2 may not be necessary. For example, as described in Patent Document 1, a photoelectric conversion element that detects a change in luminance as a voltage change may be used.

<Detector 201>
A detection unit 201 detects a subject based on the address event signal. That is, a specific subject (for example, a human eye) set in advance as a detection target is continuously detected from the luminance change information output by the event-based sensor. As one of the specific processes, the image processing unit 203 first generates a frame image by integrating the address event signal output by the event-based sensor for a certain period of time. The detection unit 203 detects feature points from the generated frame image, and detects the location of the subject (and the presence or absence of the specific subject) by pattern matching with the feature points detected from the template image of the specific subject. A position where the degree of similarity with the template is equal to or greater than a predetermined value can be detected as the position of the subject. However, the subject detection method may be another method instead of pattern matching. For example, the subject may be detected by having a CNN (convolutional neural network) machine-learn the shape of the subject in the generated frame image. Alternatively, the address event signal (brightness change information) output by the event-based sensor may be machine-learned as it is by the CNN without being converted into a frame image. Alternatively, the object may be detected from the number and range of pixels that react from the address event signal without generating an image.

Here, as described above, the event-based sensor detects an address event only when the difference between the time intervals at which the number of incident photons reaches the first threshold is equal to or greater than the second threshold (predetermined threshold). output. For example, if the predetermined threshold is fairly large, there is a possibility that the address event signal will not be output if the movement of the subject is small. Conversely, when the predetermined threshold value is small, every movement of the subject or objects included in the scene is output as the address event signal, which makes it rather difficult to detect the subject. On the other hand, the detection unit 201 cannot detect a subject unless an address event signal is output. Therefore, the predetermined threshold is a value that should be appropriately set according to the situation, and there is a possibility that the detection accuracy of the detection unit 201 is improved by appropriately setting the predetermined threshold.

Location information (coordinates, for example) of the detected object is output to an external device via an output interface such as a network cable (not shown). Alternatively, the imaging apparatus 100 may include a display unit, and the location of the subject may be displayed in a form superimposed on a frame image obtained by integrating luminance changes output by the event-based sensor for a certain period of time.

<Stimulation control unit 202>
The stimulus control unit 202 generates a stimulus that can be perceived by the subject and controls the output device 200 to output the stimulus. The stimulus given to the subject may be a stimulus that changes the position of the subject within the angle of view of the imaging device 100. For example, if the subject is a human eye, illumination light may be emitted. When the human eye is illuminated with light, the eye can be moved by a reflex reaction.

<Effect of the present invention>
In the imaging apparatus of the present invention, when the detection unit 201 cannot detect the subject for a period longer than a specific threshold, the stimulus control unit 202 controls the stimulus given to the subject. By adopting such a configuration, it is possible to suppress deterioration in subject detection accuracy. Explanation is given below.

Consider a use case in which an information processing device using an event-based sensor is used to continuously detect a specific subject. The event-based sensor outputs a luminance change as an address event signal only when there is a luminance change equal to or greater than a predetermined threshold. Therefore, when the movement of the subject is small and the change in brightness is less than the predetermined threshold, the address event signal is not output, so the subject cannot be detected. Therefore, in the information processing apparatus of the present embodiment, when the subject cannot be detected, the stimulus is controlled to move the subject to generate a luminance change equal to or greater than a predetermined threshold. When a change in luminance equal to or greater than a predetermined threshold occurs, an address event signal is output from the event-based sensor, making it possible to detect the subject.

It should be noted that, as disclosed in Japanese Patent Laid-Open No. 2002-100000, when the object cannot be detected, a method of detecting a small luminance change by increasing the detection sensitivity for an address event is also conceivable. However, if the detection sensitivity for the address event is increased (that is, the predetermined threshold value is decreased), luminance changes caused by random noise such as photon shot noise will also be detected. As a result, luminance changes due to minute movements of the subject are buried in luminance changes due to random noise, and the accuracy of subject detection is lowered.

On the other hand, the information processing apparatus according to the present embodiment does not increase the detection sensitivity for the address event, and by moving the subject to increase the luminance change due to the movement of the subject, the luminance change due to the movement of the subject is output as an address event signal. be done. Therefore, luminance changes due to movement of the subject are not buried in luminance changes due to random noise, and it is possible to suppress deterioration in subject detection accuracy.

<Stimulation variation 1>
Stimuli such as illuminating light, sound, display of images or characters, and vibration of the base are effective. Alternatively, the stimulus generated by the stimulus control unit 202 may be a stimulus that changes the position of the subject within the angle of view of the information processing apparatus 100 . When the subject is a creature such as a human being, the following method can be used, for example. The information processing apparatus 100 includes an illumination unit, emits illumination, and moves a subject by a reflex reaction. The information processing apparatus 100 includes an audio output unit, sounds a sound, and moves the subject by guiding the line of sight in the direction of the sound. The information processing apparatus 100 includes a display unit, and displays images and characters on the display unit to guide the line of sight and move the subject. Further, when the subject is an object rather than a living creature such as a human being, the base on which the object is mounted and the information processing apparatus 100 are linked, and the stimulus control unit 202 controls the vibration of the base. It should be controlled.

<Stimulation variation 2>
The stimulus may be illumination light in a wavelength range to which the event-based sensor outputting the address event has no sensitivity. For example, when the information processing apparatus 100 includes an illumination unit and the object is moved by illuminating it, it is preferable to use illumination with a wavelength to which the photoelectric conversion element 1011 has no sensitivity. This is because, if the photoelectric conversion element 1011 has sensitivity to the wavelength of illumination, even a change in luminance due to illumination is detected as an address event. This is because the

Specifically, the event-based sensor may be provided with an infrared cut filter on the light incident side, and an infrared LED may be used as the illumination. Since the light emitted by the infrared LED is absorbed by the infrared cut filter, it does not enter the photoelectric conversion element 102, and the change due to illumination is not detected as an address event. On the other hand, since the human eye reacts to infrared light as well, it is possible to detect changes in luminance due to subject movement as address events without detecting changes in luminance due to lighting irradiation. can suppress the decrease in

<Modification 1>
If the subject is not detected even after applying the stimulus to the subject, the following processing can be considered. One is to change the intensity of the stimulus. In other words, it is preferable to change at least one of the intensity, direction, and type of stimulation generated by the stimulation control section 202 . For example, a case where an object is moved by illumination will be described. If the subject could not be detected even when the illumination was applied, there is a possibility that the illumination intensity was weak and the movement of the subject was small, and the brightness change was not greater than or equal to the predetermined threshold. Therefore, when the subject cannot be detected, the illumination intensity is increased and the subject is greatly moved. That is, if the intensity of the stimulus controlled by the stimulus control unit is changeable, and the stimulus control unit changes the intensity of the stimulus given by the stimulus control unit when the subject cannot be detected even if the stimulus is applied to the object. good. As a result, it is possible to generate a change in luminance equal to or greater than a predetermined threshold value and detect the subject.

The second is to change the type of stimulus. There is a possibility that the environment is such that the subject is less likely to feel stimulation from lighting. For example, there is a possibility that the ambient light is too bright, the illumination emitted by the information processing apparatus 100 is buried in the ambient light, the subject does not feel the stimulus of the illumination, and the luminance change equal to or greater than the predetermined threshold does not occur. . Therefore, the stimulus given to the subject is a different kind of stimulus from lighting, for example, by emitting a sound, moving the subject by guiding the line of sight in the direction of the sound, and causing a luminance change greater than or equal to a predetermined threshold. , makes it possible to detect an object. That is, the stimulus control unit may have a plurality of types of stimuli to control, and if the stimulus is applied to the subject but the subject cannot be detected, the stimulus control unit may change the type of stimulus to be applied. As a result, it is possible to detect a subject by generating a change in luminance equal to or greater than a predetermined threshold.

A third method is to change the direction of stimulation. If the subject moves with a luminance change less than a predetermined threshold while the subject cannot be detected for a certain period of time or more, there is a possibility that the movement of the subject cannot be detected. Therefore, if the subject cannot be detected, the illumination direction is changed, such as by changing the illumination range or widening the illumination angle, so that the subject is illuminated. That is, if the direction of the stimulus controlled by the stimulus control unit can be changed, and if the subject cannot be detected even if the stimulus is applied to the subject, the direction of the stimulus applied by the stimulus control unit is changed. good. As a result, it is possible to detect the object by causing a change in luminance equal to or greater than the threshold.

<Modification 2>
The detection unit 201 may perform tracking processing by storing the position of the subject detected using the memory 103 . At that time, if the subject has not moved from its original location as a result of detecting the subject after the stimulus is generated by the stimulus control section 202, it is preferable to reduce the frequency of stimulus generation by the stimulus control section 202. - 特許庁Specifically, in a configuration for controlling the stimulation given to a subject when a period in which the subject cannot be detected continues for a predetermined time or longer, a predetermined threshold value is increased when the subject has not moved from its original location. is preferred. By increasing the predetermined threshold value, the stimulation control unit 202 reduces the frequency of stimulation, which leads to a reduction in power consumption for lighting control, voice control, etc. for stimulating the subject.

On the other hand, if the subject has moved from its original location, it can be seen that the subject has moved with a luminance change less than the threshold. In such a case, it is preferable to increase the frequency of stimulation by stimulation control section 202 . That is, when the subject is detected at a position different from the stored position of the subject, the detection unit 201 reduces the predetermined threshold. Specifically, in a configuration that controls the stimulus given to a subject when the subject cannot be detected for a period of time longer than a specific threshold, if the subject has moved from its original location, the predetermined threshold is set to a smaller value. It is preferable to By decreasing the predetermined threshold value, the stimulus control unit 202 generates stimuli more frequently, thereby reducing the possibility of overlooking movement of the subject due to changes in brightness less than the predetermined threshold value. Whether or not the subject is moving may be determined, for example, by determining whether or not the amount of movement of the position of the center of gravity of the subject is greater than a specific number of pixels. The specific number of pixels is preferably one pixel or more and 1/10 or less of the angle of view.

Furthermore, when the subject cannot be detected even if the stimulus is applied to the subject by the stimulus control unit 202, and it becomes possible to detect the subject for the first time by changing the direction of the stimulus such as the irradiation direction of the lighting, It can be seen that the subject moves significantly with luminance changes less than the predetermined threshold. In such a case, it is preferable to further reduce the predetermined threshold. Reducing the predetermined threshold increases the frequency of stimulus generation by the stimulus control unit 202, thereby reducing the possibility of overlooking movement of the subject due to luminance changes less than the threshold.

<Modification 3>
The display control unit 204 causes the display unit 104 to output the address event signal or the subject detection result. The display control unit 204 may display a frame image that has undergone image processing based on the address event signal. Further, control may be performed to notify the user of an error when the subject is not detected.

Furthermore, it is preferable to have a configuration in which it is possible to recognize that the subject is being stimulated when the subject is being stimulated. For example, the information processing apparatus 100 may have the display unit 104, and may be configured to display text information or the like indicating that the stimulus is being given when the stimulus is being given. With such a configuration, it is possible to distinguish whether the subject is being moved by a stimulus from the imaging device or whether the subject itself is moving.

Further, the information processing apparatus 100 has a processing unit that processes the output of the photoelectric conversion element 1011 to generate a frame image, and is configured to display the frame image on the display unit, where the stimulus is applied. is displayed in a superimposed manner on the image.

<Overall flow chart>
FIG. 4 is a flowchart for explaining the operation of the information processing apparatus 100 according to this embodiment. The processing shown in the flowchart of FIG. 4 is executed according to a computer program stored in the memory 103 by the CPU 102 of FIG. 1, which is a computer. In the following description, notation of each process (step) is omitted by adding S to the beginning of each process (step). In S<b>11 , the detection unit 201 determines whether or not a period in which the subject cannot be detected continues for a predetermined time or longer. As a result of the determination, if the stimulus control unit 202 determines that the stimulus is equal to or greater than the specific threshold, the stimulus control unit 202 generates and outputs a stimulus to be given to the subject (S12). If it is less than the predetermined time, the detection unit 201 continues detection of the subject without changing the stimulus given to the subject (continues S11).

In S13, the detection unit 201 determines whether or not the subject has been detected as a result of giving the stimulus to the subject. If the subject has been detected, the detection unit 201 further determines whether the subject has moved (S19). On the other hand, if the subject cannot be detected, the stimulus control section 202 changes the intensity of the stimulus given to the subject (S14).

In S15 following S14, it is determined whether or not the subject has been detected as a result of changing the intensity of the stimulus given to the subject. If the object can be detected, the process returns to S11, the original stimulus given to the object is restored, and the object detection is continued. On the other hand, if the subject cannot be detected, the stimulus control section 202 changes the type of stimulus given to the subject (S16).

In S17 following S16, the detection unit 201 determines whether or not the subject has been detected as a result of changing the type of stimulation given to the subject. If the object can be detected, the process returns to S11, the stimulus output is terminated, and the object detection continues. On the other hand, if the subject cannot be detected, the stimulus control section 202 changes the direction of the stimulus given to the subject (S18).

If it is determined in S19 that the position of the object has not moved, the predetermined threshold is increased (S20). On the other hand, if it is determined that the position of the subject has moved, the predetermined threshold is lowered (S21). Furthermore, in S22 following S18, the predetermined threshold value is further increased from that in S21.

The present invention is also realized by executing the following processing. That is, the software (program) that implements the functions of the above-described embodiments is supplied to the system or device via a network for data communication or various storage media. Then, the computer (or CPU, MPU, etc.) of the system or device reads and executes the program. Alternatively, the program may be recorded on a computer-readable recording medium and provided.

100 information processing device 200 output device 101 imaging unit 201 detection unit 202 stimulus control unit 203 image processing unit

Claims (17)

An information processing device that acquires an address event signal indicating the position and time of a pixel at which a luminance change occurs,
detection means for detecting a subject based on the address event signal;
and generating means for generating a stimulus perceivable by the subject when the subject is not detected for a period longer than a predetermined time. 2. The information processing apparatus according to claim 1, wherein said stimulus is illumination light, sound, display of images or characters, or vibration of a base. 3. The imaging apparatus according to claim 2, wherein the stimulus is illumination light in a wavelength range to which an event-based sensor that outputs the address event has no sensitivity. 4. The method according to any one of claims 1 to 3, wherein said generating means changes the intensity of said stimulus when said subject is not detected by said detecting means even after applying said stimulus to said subject. The information processing apparatus according to any one of items 1 and 2. 5. The method according to any one of claims 1 to 4, wherein said generating means changes the type of stimulus when said subject is not detected by said detecting means even after applying said stimulus to said subject. The information processing device according to item 1. 6. The generating means changes the direction of the stimulus when the subject is not detected by the detecting means even after applying the stimulus to the subject. The information processing device according to item 1. the detection means detects the subject based on the position of a pixel in which the address event signal is greater than a predetermined threshold;
7. The information processing apparatus according to claim 6, wherein said threshold is made smaller when said subject is detected by said detecting means after said stimulus whose direction has been changed is applied to said subject. the address event signal is output for a pixel having a luminance change greater than a predetermined threshold;
further comprising storage means for storing the position of the subject detected by the detection means;
When the object is detected at a position different from the position of the object stored by the storage means after the stimulus is applied to the object, the detection means reduces the predetermined threshold. 8. The information processing apparatus according to any one of claims 1 to 7. The detection means increases the threshold when the subject is detected at the same position as the position of the subject stored by the storage means after the stimulus is applied to the subject, The information processing apparatus according to claim 8 . 10. The information processing apparatus according to any one of claims 1 to 9, further comprising notifying means for notifying that said stimulus has been generated. 11. The information processing apparatus according to claim 10, wherein said notification means notifies an error when said subject is not detected by said detection means even after said stimulus is given to said subject. 12. An information processing apparatus according to any one of claims 1 to 11, further comprising control means for controlling a predetermined mechanism for representing said stimulus generated by said generating means. 13. The detector according to any one of claims 1 to 12, wherein said detection means detects said object having a predetermined shape based on the position of a pixel having a specific signal included in said address event signal. The information processing device according to the item. 14. The information processing apparatus according to any one of claims 1 to 13, wherein said address event signal is output by a photoelectric conversion element having a pixel that outputs a signal in response to incident photons. 15. The information processing apparatus according to claim 1, further comprising display means for displaying said address event signal and said object detected by said detection means. A program for causing a computer to function as each unit included in the information processing apparatus according to any one of claims 1 to 15. An information processing method for acquiring an address event signal indicating the position and time of a pixel at which a luminance change occurs, comprising:
a detection step of detecting a subject based on the address event signal;
and a generating step of generating a stimulus perceivable by the subject when the subject is not detected for a period longer than a predetermined time.

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