Patent Publication Number: US-2022214434-A1

Title: Gating camera

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a gating camera. 
     2. Description of the Related Art 
     In order to support autonomous driving or autonomous control of the light distribution of a headlamp, an object identification system is employed for sensing the position and the kind of an object that exists in the vicinity of a vehicle. The object identification system includes a sensor and a calculation processing device configured to analyze the output of the sensor. As such a sensor, a desired one is selected from among a camera, LiDAR (Light Detection and Ranging, Laser Imaging Detection and 
     Ranging), millimeter-wave radar, ultrasonic sonar, etc., giving consideration to the usage, required precision, and cost. 
     Typical monocular cameras are not capable of acquiring depth information. Accordingly, in a case in which there is overlap between multiple objects positioned at different distances, it is difficult to separate individual objects. 
     As a camera that is capable of acquiring the depth information, TOF cameras are known. A TOF (Time Of Flight) camera is configured to emit infrared light by means of a light-emitting device, to measure the time of flight up to the time point at which the reflected light returns to the image sensor, and to convert the time of flight into distance information in the form of an image. 
     As an alternative to a TOF camera, the present applicant has proposed a gating camera (or gated camera) (Japanese Patent Application Laid Open No. 2009-257983, International Publication WO 2017/110413A1). A gating camera is configured to divide its image capture range into multiple image capture ranges, and to capture multiple images for respective ranges at different exposure timings and different exposure periods. With this, a slice image is acquired for each target image capture range. Each slice image includes only an object in the corresponding image capture range. 
     1. As a result of investigating gating cameras, the present inventors have come to recognize the following problem.  FIGS. 1A and 1B  are diagrams for explaining a problem that occurs in a gating camera.  FIG. 1A  shows an example of a situation in which the gating camera captures images. In a case in which the image capture range is designed to have a narrow depth, this leads to an object existing across multiple image capture ranges.  FIG. 1A  shows a situation in which images of an automobile are captured from the front with an image capture range depth of 1.5 m.  FIG. 1B  shows multiple slice images acquired in the image capture situation shown in  FIG. 1A . A slice image IMGs i  that corresponds to an image capture range includes only a part of the bumper or hood of the automobile. A different slice image IMGs i+1  includes only a part of the hood or windshield of the automobile. Accordingly, it is difficult to recognize what the object is based on the individual slice images IMGs. 
     By increasing the depth of the image capture range to on the order of several dozen m, such an arrangement is capable of solving this problem. However, in a case in which the depth of the image capture range is excessively increased, there is a high probability that there will be a range including an object that differs from the object of interest. This degrades the advantage of the gating camera. 
     2. With such a gating camera, the image transmission rate from an image sensor to an image processing unit becomes a bottleneck. That is to say, the image sensor can be operated with a very high frame rate. However, the time required for the gating camera to generate slice images for all the image capture ranges (which will be referred to as the “image capture time of the gating camera”) is limited by the transmission rate. 
     3. An active sensor such as a gating camera or the like is configured to illuminate probe light to an object, and to detect the reflected light. The active sensor mainly includes a light projector (illumination apparatus) configured to illuminate light to an object and a photosensor configured to detect the reflected light from the object. By providing matching between the wavelength of the probe light and the sensitivity wavelength range of the sensor, this allows the active sensor to have an advantage of improved resistance with respect to disturbance as compared with a passive sensor. 
     In a case in which there is a pulsed light source that emits light having the same wavelength as that provided by the illumination apparatus of the active sensor at a cycle that is an integer multiple or an integer fraction of the light-emission cycle of the active sensor, this drastically degrades the detection precision of the active sensor. 
     SUMMARY 
     Description will be made regarding an outline of several example embodiments of the present disclosure. In this outline, some concepts of one or more embodiments will be described in a simplified form as a prelude to the more detailed description that is presented later in order to provide a basic understanding of such embodiments. Accordingly, the outline is by no means intended to restrict the scope of the present invention or the present disclosure. Furthermore, this outline is not an extensive overview of all conceivable embodiments, and is by no means intended to restrict essential elements of the embodiments. For convenience, the term “one embodiment” may be used herein to refer to a single embodiment (example or modification) or multiple embodiments (examples or modifications) disclosed in the present specification. 
     SUMMARY 
     1. A gating camera according to an embodiment includes: an illumination apparatus structured to illuminate probe light; an image sensor; a camera controller structured to control a timing at which the illumination apparatus illuminates the probe light and a timing at which the image sensor is exposed, such that the image sensor outputs a slice image for each of image capture ranges divided in the depth direction while changing the image capture range, and such that each slice image includes only an object included in the corresponding image capture range; and an image processing unit structured to generate a final image including an entire object of interest (OOI) based on the multiple slice images that correspond to the multiple image capture ranges. 
     With this embodiment, this is capable of generating a final image including an entire object of interest with image capture ranges each having a small depth. 
     Also, the final image may include only the object of interest. With such an arrangement in which objects other than the object of interest are removed, this provides improved visibility in a case in which the final image is displayed on a display. Alternatively, this facilitates downstream processing such as object identification for the object of interest. 
     Also, the image processing unit may combine the multiple slice images so as to generate a combined image including distance information for each pixel, and may extract a region including the object of interest from the combined image. With such an arrangement in which the distance information provided by the intermediate image is used as a reference, this allows an object to be extracted in a simple manner. 
     A gating camera according to an embodiment includes: an illumination apparatus structured to illuminate probe light; an image sensor; a camera controller structured to control a timing at which the illumination apparatus illuminates the probe light and a timing at which the image sensor is exposed, such that the image sensor outputs a slice image for each of image capture ranges divided in the depth direction while changing the image capture range, and such that each slice image includes only an object included in the corresponding image capture range; and an image processing unit structured to combine the multiple slice images that correspond to the multiple image capture ranges so as to generate a combined image having distance information for each pixel. 
     With such an arrangement in which the distance information provided by the intermediate image is used as a reference, this allows an object to be extracted in a simple manner. 
     2. A gating camera according to an embodiment includes: an illumination apparatus structured to illuminate probe light; an image sensor; a camera controller structured to control a timing at which the illumination apparatus illuminates the probe light and a timing at which the image sensor is exposed, such that the image sensor outputs a slice image for each of image capture ranges divided in the depth direction while changing the image capture range, and such that each slice image includes only an object included in the corresponding image capture range; and an image processing unit structured to receive a slice image from the image sensor and to process the slice image. The camera controller is configured to be capable of adaptively controlling the data amount of the slice image transmitted from the image sensor to the image processing unit. 
     With such an arrangement in which the data amount of the slice image to be transmitted is reduced according to a situation, this allows the transmission time to be shortened, thereby allowing the image capture time to be reduced. 
     Also, the camera controller may instruct the image sensor or an interface (image transmission circuit) arranged between the image sensor and the image processing unit to crop a part of the slice image so as to reduce the size of the slice image to be transmitted. With such an arrangement in which only a necessary portion is cropped and transmitted, this allows the data amount to be reduced. 
     Instead of or in addition to cropping, the resolution may be reduced by binning or thinning processing so as to reduce the data amount. 
     An object at a near distance moves at a relatively fast speed in the slice image. In this case, in a case in which such a cropping region is determined at a given time point as a reference, there is high probability that such an object will deviate from the cropping region after the cropping region is determined. In contrast, an object at a far distance moves at a relatively slow speed in the slice image. In this case, such an object remains in the cropping region for a long period of time. Furthermore, there is a high probability that such an object at a far distance appears in a concentrated manner in the vicinity of the vanishing point. Accordingly, a slice image group that corresponds to an image capture range group that is nearer than a predetermined distance may always be transmitted without cropping. Also, whether or not the slice image is to be cropped may be controlled for a slice image group that corresponds to an image capture range group that is farther than the predetermined distance. This allows slice images including the object of interest to be transmitted. 
     Also, the gating camera may be configured such that multiple slice images may be transmitted without cropping. Also, whether or not multiple subsequent slice images are to be cropped may be determined based on the multiple uncropped slice images. With this, the situation of future slice images may be predicted and estimated based on the slice images that have not been cropped, so as to determine whether or not subsequent images are to be cropped. 
     Also, in a first mode, all slice images that correspond to all image capture ranges may be transmitted without cropping. Also, when a far-side slice image group that corresponds to an image capture range group that is farther than a predetermined distance transmitted in the first mode includes only a single object of interest, the mode may be switched to a second mode. Also, in the second mode, the far-side slice image group may be transmitted after a region of interest thereof including the object of interest is cropped. 
     Also, the illumination apparatus may be structured to be capable of focusing and diffusing the probe light so as to provide a variable illumination range. Also, when a slice image is to be transmitted with cropping, the camera controller may instruct the illumination apparatus to focus the probe light. In a case in which image capture is to be performed for the far-side image capture ranges, large attenuation occurs in the probe light and the reflected light thereof. Accordingly, a single exposure is insufficient for generating a slice image having sufficient brightness. In this case, the following processing is required. That is to say, exposure is executed multiple times for such a far-side image capture range. The slice images acquired for the respective exposures are combined so as to generate a single slice image. By focusing the probe light, this allows a slice image acquired in a single exposure to have an increased brightness. Such an arrangement allows the number of times the exposure is to be executed, i.e., the number of times the slice images are to be transmitted, to be reduced. This allows the image capture time to be shortened. 
     A gating camera according to an embodiment includes: an illumination apparatus structured to illuminate probe light, and to be capable of focusing and diffusing the probe light so as to provide a variable illumination range; an image sensor; a camera controller structured to control a timing at which the illumination apparatus illuminates the probe light and a timing at which the image sensor is exposed, such that the image sensor outputs a slice image for each of image capture ranges divided in the depth direction while changing the image capture range, and such that each slice image includes only an object included in the corresponding image capture range; and an image processing unit structured to receive the slice images from the image sensor, and to process the slice images. The camera controller controls an illumination range of the illumination apparatus based on detection results obtained by the image processing unit. 
     In a case in which image capture is to be performed for the far-side image capture ranges or image capture is performed in dense fog, large attenuation occurs in the probe light and the reflected light thereof. Accordingly, a single exposure is insufficient for generating a slice image having sufficient brightness. In this case, the following processing is required. That is to say, exposure is executed multiple times for such a far-side image capture range. The slice images acquired for the respective exposures are combined so as to generate a single slice image. By focusing the probe light, this allows a slice image acquired in a single exposure to have an increased brightness. Such an arrangement allows the number of times the exposure is to be executed, i.e., the number of times the slice images are to be transmitted, to be reduced. This allows the image capture time to be shortened. 
     Also, in a first mode, the probe light may be illuminated to an entire illumination range. Also, in the first mode, when the image processing unit detects an object of interest in the slice image that corresponds to a predetermined image capture range, the first mode may be switched to a second mode. Also, in the second mode, when an image is captured for the predetermined image capture range, the probe light may be illuminated to a region of interest including the object of interest. 
     An active sensor according to an embodiment includes: a light emitting apparatus structured to emit a pulsed light multiple times at non-uniform time intervals; and a photosensor structured to detect reflected light from an object at a timing in synchronization with light emission of the light emitting apparatus for every light emission. 
     The photosensor operates in synchronization with the operation of the light emitting apparatus included in the same active sensor. Accordingly, even in a case in which the light emission timing is changed, the reflected light from the object is incident to the photosensor at the same timing. Accordingly, the detection values of the reflected light are integrated, thereby allowing a large signal component to be acquired. In contrast, other noise light sources emit light at a timing that is asynchronous with respect to the exposure timing of the photosensor. This is capable of reducing the probability that the timing at which noise light from such a noise light source is incident to the photosensor is included in the exposure timing of the photosensor. This allows the effects of such pulsed light sources in the vicinity to be reduced. 
     Also, one instance of sensing including a single light emission of the light emitting apparatus and a single exposure of the photosensor may be repeatedly executed with a predetermined cycle. Also, the light emission timing of the light emitting apparatus in the predetermined cycle may be changed for each sensing. 
     Also, the active sensor may be structured as a gating camera structured to change a time difference between light emission and image capture for each of ranges divided in the depth direction, so as to be capable of acquiring multiple images that correspond to the multiple ranges. 
     Also, the active sensor may be structured as a Time Of Flight (TOF) camera. 
     Also, the active sensor may be structured as a LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging). 
     ADVANTAGE OF THE PRESENT INVENTION 
     With an embodiment, this is capable of generating an image including an entire object of interest with image capture ranges having a reduced depth. With an embodiment, this allows the image capture time of the gating camera to be shortened. With an embodiment, this is capable of reducing the effects of the active sensors in the vicinity. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will now be described, by way of example only, with reference to the accompanying drawings which are meant to be exemplary, not limiting, and wherein like elements are numbered alike in several Figures, in which: 
         FIGS. 1A and 1B  diagrams for explaining a problem that occurs in a gating camera; 
         FIG. 2  is a block diagram showing a gating camera according to an embodiment  1 ; 
         FIG. 3  is a diagram for explaining an image capture operation of the gating camera; 
         FIG. 4  is a diagram showing an example of an image capture situation; 
         FIG. 5  is a diagram showing three slice images IMGs i  through IMGs i+2  from among all the slices IMGs 1  through IMGs N  acquired in the driving situation shown in  FIG. 4 ; 
         FIG. 6  is a diagram showing a final image IMGf generated by an image processing unit; 
         FIG. 7  is a diagram for explaining a combined image IMGc generated by the image processing unit; 
         FIGS. 8A through 8C  are diagrams each showing a specific example of generating processing for generating the combined image IMGc provided by the image processing unit; 
         FIGS. 9A through 9C  are diagrams for explaining the generation of the final image IMGf based on the combined image IMGc; 
         FIG. 10  is a block diagram showing a gating camera according to an embodiment 2; 
         FIG. 11  is a diagram for explaining an image capture operation of the gating camera; 
         FIGS. 12A and 12B  are diagrams for explaining an example of cropping processing for cropping the slice image IMGs; 
         FIGS. 13A and 13B  are diagrams for explaining image capture and transmission of the slice image; 
         FIG. 14  is a flowchart showing an example of mode control provided by the gating camera; 
         FIG. 15  is a diagram showing an example of a situation in which the mode is switched to a second mode; 
         FIG. 16  is a block diagram showing a gating camera according to an embodiment 3; 
         FIG. 17  is a block diagram showing a gating camera according to an embodiment 4; 
         FIG. 18  is a block diagram showing an active sensor according to an embodiment 5; 
         FIG. 19  is a time chart showing the relation between the light emission timing of the light emitting apparatus and the exposure timing of the photosensor; 
         FIG. 20  is an operating waveform diagram showing the operation of an active sensor according to a comparison technique; 
         FIG. 21  is an operating waveform diagram showing the operation of the active sensor shown in  FIG. 18 ; 
         FIG. 22  is a block diagram showing a gating camera according to an example; 
         FIG. 23  is a diagram for explaining the operation of the gating camera; 
         FIGS. 24A and 24B  are diagrams for explaining an image acquired by the gating camera; 
         FIG. 25  is a diagram showing an automotive lamp including a gating camera or an active sensor as a built-in component; and 
         FIG. 26  is a block diagram showing an automotive lamp provided with an object identification system. 
     
    
    
     DETAILED DESCRIPTION 
     Description will be made below regarding the present invention based on preferred embodiments with reference to the drawings. The same or similar components, members, and processes are denoted by the same reference numerals, and redundant description thereof will be omitted as appropriate. The embodiments have been described for exemplary purposes only, and are by no means intended to restrict the present invention. Also, it is not necessarily essential for the present invention that all the features or a combination thereof be provided as described in the embodiments. 
     Embodiment 1 
       FIG. 2  is a block diagram showing a gating camera  20  according to an embodiment 1. The gating camera  20  captures images for a plurality of N (N≥2) ranges RNG 1  through RNG N  divided in the depth direction. For example, the depth of a single image capture range is designed on the order of 1 to 2 m (e.g., 1.5 m). Description will be made assuming that N=100. 
     The gating camera  20  includes an illumination apparatus  22 , an image sensor  24 , a camera controller  26 , and an image processing unit  28 . 
     The illumination apparatus  22  illuminates probe light L 1  in front of the vehicle in synchronization with a light emission timing signal S 1  supplied from the camera controller  26 . The probe light L 1  is preferably generated as infrared light. However, the present invention is not restricted to such an arrangement. Also, the probe light L 1  may be visible light having a predetermined wavelength. 
     The image sensor  24  is configured to support exposure control in synchronization with an exposure timing signal S 2  supplied from the camera controller  26 , and to be capable of generating slice images IMGs. The image sensor  24  is sensitive to the same wavelength as that of the probe light L 1 . The image sensor  24  captures images of reflected light (returned light) L 2  reflected by the object OBJ, and outputs slice images IMGs. 
     The camera controller  26  holds light emission timing and exposure timing determined for each of the image capture ranges RNG 1  through RNG N . When an image is captured for a given image capture range RNG i , the camera controller generates the light emission timing signal S 1  and the exposure timing signal S 2  based on the light emission timing and the exposure timing that correspond to the corresponding image capture range, and captures images. The i-th slice image IMGs i  includes an object included in the corresponding image capture range RNG i . 
     In the present embodiment, the camera controller  26  captures images while changing the image capture range RNG i  in the depth direction, so as to generate the slice images IMGs 1  through IMGs N  for all the image capture ranges RNG 1  through RNG N . 
       FIG. 3  is a diagram for explaining the image capture operation of the gating camera  20 .  FIG. 3  shows the operation when the i-th image capture range RNG i  is measured as the range of interest (ROI). The illumination apparatus emits light during a light-emitting period τ 1  from the time point t 0  to t 1  in synchronization with the light emission timing signal S 1 . In the upper diagram, a light beam diagram is shown with the horizontal axis as time and with the vertical axis as distance. The distance between the gating camera  20  and the near-distance boundary of the image capture range RNG i  is represented by d MINi . The distance between the gating camera  20  and the far-distance boundary of the image capture range RNG i  is represented by d MAXi . 
     The round-trip time T MINi , which is a period from the departure of light from the illumination apparatus  22  at a given time point, to the arrival of the light at the distance d MINi , up to the return of the reflected light to the image sensor  24 , is represented by T MINi =2×d MINi /c. Here, c represents the speed of light. 
     Similarly, the round-trip time T MAXi , which is a period from the departure of light from the illumination apparatus  22  at a given time point, to the arrival of the light at the distance d MAXi , up to the return of the reflected light to the image sensor  24 , is represented by T MAXi =2×d MAXi /c. 
     When only an image of an object OBJ included in the image capture range RNG i  is to be captured, the camera controller  26  generates the exposure timing signal S 2  so as to start the exposure at the time point t 2 =t 0 +T MINi , and so as to end the exposure at the time point t 3 =t 1 +T MAXi . This is a single exposure operation. 
     When an image is captured for the i-th range RNG i , the exposure may be executed multiple times (multiple exposures). In this case, preferably, the camera controller  26  may repeatedly execute the above-described exposure operation multiple times with a predetermined period τ 2 . 
     Returning to  FIG. 2 , the image processing unit  28  receives the input of multiple slice images IMGs 1  through IMGs N  that correspond to the multiple image capture ranges RNG 1  through RNG N . The image processing unit  28  generates a single final image IMGf including an object of interest (OOI) based on the multiple slice images IMGs 1  through IMGs N . 
     The above is the configuration of the gating camera  20 . Next, description will be made regarding the operation thereof. 
       FIG. 4  is a diagram showing an example of an image capture situation. A vehicle OBJ 1  and a pedestrian OBJ 2  are in front of the gating camera  20 . The vehicle OBJ 1  exists across multiple image capture ranges RNG i  through RNG i+2 . The pedestrian OBJ 2  is included in the image capture range RNG i . 
       FIG. 5  is a diagram showing three slice images IMGs i  through IMGs i+2  from among all the slice images IMGs 1  through IMGs N  acquired in the driving situation shown in  FIG. 4 . Each slice image IMGs i  includes only an object included in the corresponding image capture range RNG i . Accordingly, the slice image IMGs i  includes the pedestrian  2  and a part of the vehicle OBJ 1 , i.e., a portion OBJ 1   A . The slice image IMGs i+1 , includes a portion OBJ 1   B  of the vehicle OBJ 1 . The slice image IMGs i+2  includes a portion OBJ 1   c  of the vehicle OBJ 1 . 
     For example, the image processing unit  28  scans all the slice images IMGs 1  through IMGs N , and sets a candidate of an object of interest included in the slice images. In this example, when the image processing unit  28  detects a part of a vehicle included in the slice image IMGs i , the vehicle is set to an object of interest. Subsequently, all the slice images IMGs 1  through IMGs N  are scanned again, and detects the slice images IMGs i+1  and IMGs i+2  including different parts of the same vehicle OBJ 1 , i.e., portions OBJ 1   B  and OBJ 1   c . The portions OBJ 1   A  through OBJ 1   c , which form the same object of interest, are extracted from the slice images IMG si  through IMGs i+2 , and are combined.  FIG. 6  is a diagram showing a final image IMGf generated by the image processing unit  28 . It should be noted that the final image IMGf does not include the pedestrian OBJ 2 , which has not been set to an object of interest. 
     The above is the operation of the gating camera  20 . With the gating camera  20 , this is capable of extracting an object of interest, and of generating a final image IMGf including the whole of the object of interest thus extracted with a reduced depth of the image capture ranges RNG. 
     The gating camera  20  has an advantage of being capable of removing objects other than the object of interest from the final image. In particular, this advantage is effectively provided under particular situations such as a snowfall situation or the like in addition to the image capture situation as shown in  FIG. 4 . In such a snowfall situation, each slice image includes a great number of small snowflakes. With the gating camera  20 , this allows such snowflakes to be removed from the final image IMGf, thereby generating an image with high visibility. 
     Next, description will be made regarding a specific example of the processing provided by the image processing unit  28 . In a step of generating the final image IMGf, the image processing unit  28  may generate a combined image IMGc, and may generate the final image IMGf based on the combined image IMGc. 
       FIG. 7  is a diagram for explaining the combined image IMGc generated by the image processing unit  28 . The slice images IMGs and the intermediate image IMGc each have X×Y pixels. The pixel of the j-th row and i-th column will be represented by P ij . The intermediate image IMGc is an image obtained by combining all the slice images IMGs 1  through IMGs N . Each pixel P ij  of the intermediate image IMGc has a brightness value L that corresponds to one slice image IMGs k  (k=1 to N) from among all the slice images IMGs 1  through IMGs N , or a brightness value L′ obtained by calculating the brightness value L. Furthermore, each pixel P ij  of the intermediate image IMGc has an identifier (k in this example) of the slice image IMGs k  that indicates the origin of the brightness value thereof. The identifier k can be regarded as distance information to the object. Accordingly, instead of the identifier k, each pixel P ij  of the intermediate image IMGc may include the distance d to the object that indicates the origin of the pixel. In the present specification, each pixel P ij  is represented in the form of [L, k]. 
     It should be noted that the format of the intermediate image IMGc is not restricted in particular. For example, the intermediate image IMGc may include two items of image data, i.e., X×Y image data that represents brightness value information and X×Y image data that represents distance information. 
       FIGS. 8A through 8C  are diagrams showing a specific example of the processing for generating the combined image IMGc provided by the image processing unit  28 . For ease of understanding, description will be made regarding an arrangement in which N=6 and each pixel has eight gradations (3 bits) from 0 to 7.  FIG. 8A  shows multiple slice images IMGs 1  through IMGs 6  that correspond to all the image capture ranges. 
     The combining method is not restricted in particular. Description will be made below regarding an example of the combining method. 
       FIG. 8B  shows the intermediate image IMGc obtained by a first generating method. In the first generating method, each pixel P ij  of the intermediate image IMGc has a brightness value that is the maximum value (or a value obtained by calculating the maximum value) from among the brightness values of the corresponding pixels P ij  of all the slice images IMGs 1  through IMGs 6 . 
       FIG. 8C  shows an intermediate image IMGc obtained by a second generating method. In the second generating method, each pixel P ij  of the intermediate image IMGc has a brightness value that is a value selected from among effective brightness values of the corresponding pixels P ij  of all the slice images IMGs 1  through IMGs 6  (or a value obtained by calculating the brightness value thus selected) such that it is selected from the nearest slice image (i.e., from the slice image at the nearest distance). The effective value may be defined as a non-zero value. Also, the effective value may be defined as a value that is larger than a predetermined threshold value. 
     The above is the description of the combined image IMGc.  FIGS. 9A through 9C  are diagrams for explaining the generation of the final image IMGf based on the combined image IMGc. 
     The combined image IMGc includes the identifier k that represents the distance to the object in addition to the brightness value L. This allows the object of interest OOI to be extracted in a simple manner. The reason is as follows. That is to say, when there is a large difference in the identifier k between given pixels, there is a high probability that the pixels belong to different objects. Conversely, when there is a small difference in the identifier k between given pixels, there is a high probability that the pixels belong to the same object. The object extraction processing algorithm can be created based on this assumption. 
     When the combined image IMGc includes multiple objects of interest OOI 1  and OOI 2 , as shown in  FIG. 9B , the final images IMGf 1  and IMGf 2  may be generated for the respective objects of interest. 
     Alternatively, when the combined image IMGc includes multiple objects of interest OOI 1  and OOI 2 , as shown in  FIG. 9C , a single final image IMGf including the multiple objects of interest may be generated. 
     After the combined image IMGc is generated, the data of the multiple original slice images IMGc 1  through IMGc N  may be discarded. This also provides an advantage of allowing the memory capacity to be reduced. 
     Embodiment 2 
       FIG. 10  is a block diagram showing a gating camera  20  according to an embodiment 2. The gating camera  20  captures images for a plurality of N (N≥2) ranges RNG 1  through RNG N  divided in the depth direction. For example, the depth d of a single image capture range is designed on the order of 1 to 2 m (e.g., 1.5 m). Description will be made assuming that N=100. 
     The gating camera  20  includes an illumination apparatus  22 , an image sensor  24 , a camera controller  32 , and an image processing unit  34 . 
     The illumination apparatus  22  illuminates probe light L 1  in front of the vehicle in synchronization with a light emission timing signal S 1  supplied from the camera controller  32 . The probe light L 1  is preferably generated as infrared light. However, the present invention is not restricted to such an arrangement. Also, the probe light L 1  may be visible light having a predetermined wavelength. 
     The image sensor  24  is configured to support exposure control in synchronization with an exposure timing signal S 2  supplied from the camera controller  32 , and to be capable of generating slice images IMGs. The image sensor  24  is sensitive to the same wavelength as that of the probe light L 1 . The image sensor  24  captures images of reflected light (returned light) L 2  reflected by the object OBJ, and outputs slice images IMGs. 
     The camera controller  32  holds light emission timing and exposure timing determined for each of the image capture ranges RNG 1  through RNG N . When an image is captured for a given image capture range RNG i , the camera controller  32  generates the light emission timing signal S 1  and the exposure timing signal S 2  based on the light emission timing and the exposure timing that correspond to the corresponding image capture range, and captures images. The i-th slice image IMGs i  includes an object included in the corresponding image capture range RNG i . 
     In the present embodiment, the camera controller captures images while changing the image capture range RNG i  in the depth direction, so as to generate the slice images IMGs i  through IMGs N  for all the image capture ranges RNG 1  through RNG N . 
       FIG. 11  is a diagram for explaining the image capture operation of the gating camera  20 .  FIG. 11  shows the operation when the i-th image capture range RNG i  is measured. The illumination apparatus  22  emits light during a light-emitting period τ 1  from the time point t 0 to t 1  in synchronization with the light emission timing signal S 1 . In the upper diagram, a light beam diagram is shown with the horizontal axis as time and with the vertical axis as distance. The distance between the gating camera  20  and the near-distance boundary of the image capture range RNG i  is represented by d MINi . The distance between the gating camera  20  and the far-distance boundary of the image capture range RNG i  is represented by 
     The round-trip time T MINi , which is a period from the departure of light from the illumination apparatus  22  at a given time point, to the arrival of the light at the distance d MINi , up to the return of the reflected light to the image sensor  24 , is represented by T MINi =2×T MINi /c. Here, c represents the speed of light. 
     Similarly, the round-trip time T MAXi , which is a period from the departure of light from the illumination apparatus  22  at a given time point, to the arrival of the light at the distance d MAXi , up to the return of the reflected light to the image sensor  24 , is represented by T MAXi =2×d MAXi /c. 
     When only an image of an object OBJ included in the image capture range RNG i  is to be captured, the controller  32  generates the exposure timing signal S 2  so as to start the exposure at the time point t 2 =t 0 +T MINi , and so as to end the exposure at the time point t 3 =t 1 +T MAXi . This is a single exposure operation. 
     When an image is captured for the i-th range RNG i , the exposure may be executed multiple times (multiple exposures). In this case, preferably, the camera controller may repeatedly execute the above-described exposure operation multiple times with a predetermined period τ 2 . 
     Returning to  FIG. 10 , the image processing unit  34  receives the slice images IMGs i  (i=1, 2, . . . , N) from the image sensor  24 , and processes the slice images IMGs i  thus received. 
     The camera controller  32  and the image processing unit  34  may be provided as separate hardware components. Otherwise, they may be configured as a single hardware component. For example, the camera controller  32  and the image processing unit  34  may be provided as a combination of a calculation processing device  30  such as a microcontroller or the like and a software component to be executed by the calculation processing device  30 . 
     The image sensor  24  and the calculation processing device  30  are coupled via an interface  26 . The interface  26  transmits the slice images IMGs from the image sensor  24  to the image processing unit  34 . The kind of the interface  26  is not restricted in particular. Examples of such an interface to be employed as the interface  26  include Mobile Industry Processing Interface (MIPI), Universal Serial Bus (USB), etc. 
     In the present embodiment, the camera controller  32  is configured to be capable of controlling at least one from among the image sensor  24  and the interface  26 , so as to adaptively control the data amount of each slice image IMGs transmitted from the image sensor  24  to the image processing unit  34 . 
     In the present embodiment, the camera controller  32  instructs the image sensor  24  or the interface  26  to crop a portion of the slice image IMGs so as to reduce the size (number of pixels) of the slice image IMGs thus transmitted, thereby reducing the data amount. The camera controller  32  generates a control signal S 3  that specifies whether or not the slice image is to be cropped. The control signal S 3  may include information on the size or the position of the region to be cropped. 
     The cropping method is not restricted in particular. In the image sensor  24 , a portion of the slice image IMGs may be cropped. That is to say, the image itself to be read out by the image sensor  24  may be cropped. Alternatively, in the interface  26 , a portion of the slice image IMGs may be cropped. That is to say, after all the pixels are read out from the image sensor  24 , a portion of the full-size image thus read out may be cropped. 
       FIGS. 12A and 12B  are diagrams for explaining an example of the cropping processing for the slice image IMGs. As shown in  FIG. 12A , when there is a high probability that only a part of the slice image IMGs obtained by the image sensor  24  includes an object OBJ, such a region (region of interest ROI) including the object OBJ is cropped, and the cropped slice image (cropped image) IMGs′ is transmitted. 
     As shown in  FIG. 12B , when there is a high probability that a single object exists or multiple objects exist over a wide region of the slice image IMGs obtained by the image sensor  24 , the original slice image IMGs is transmitted without cropping. 
     An object at a near distance moves at a relatively fast speed in the slice image. In this case, in a case in which such a cropping region is determined at a given time point as a reference, there is high probability that such an object will deviate from the cropping region after the cropping region is determined. In order to solve such a problem, in the present embodiment, a slice image that corresponds to a near distance is always transmitted without cropping. This prevents the loss of such an object. 
     In contrast, an object at a far distance moves at a relatively slow speed in the slice image. In this case, such an object remains in the cropping region for a long period of time. Furthermore, there is a high probability that such an object at a far distance appears in a concentrated manner in the vicinity of the vanishing point. 
     Accordingly, in the present embodiment, the slice image group IMGs 1  through IMGs Y  that corresponds to an image capture range group (10 to 100 m) that is nearer than a predetermined distance (e.g., 100 m) may always be transmitted as it is without cropping. In contrast, judgment may be made regarding whether or not cropping is to be executed for the slice image group IMGs Y+1  through IMGs N  that corresponds to an image capture range group (100 to 150 m) that is farther than a predetermined distance (e.g., 100 m). 
     It should be noted that the calculation processing device  30  is not able to monitor the slice image IMGs acquired by the image sensor  24  before transmission. Accordingly, with the present embodiment, the camera controller  32  is required to estimate the state of the current slice image IMGs based on a slice image IMGs previously received by the image processing unit  34  without cropping, so as to judge whether or not cropping is to be executed. 
     Accordingly, the gating camera  20  transmits all the slice images IMGs 1  through IMGs N  without cropping. Subsequently, judgment may be made based on the slice image group IMGs 1  through IMGs N  that has not been cropped regarding whether or not cropping is to be executed for the subsequent slice image group IMGs 1  through IMGs N . This is capable of predicting and estimating the state of slice images that will be acquired in the future based on the slice images that have not been cropped. This allows judgment to be made regarding whether or not the further slice image is to be cropped. In this case, the position and the size of the cropping region may be determined in addition to the determination of whether or not the cropping is to be executed. 
     The above is the basic configuration of the gating camera  20 . Next, description will be made regarding the operation thereof. 
       FIGS. 13A and 13B  are diagrams for explaining image capture and transmission of the slice images.  FIG. 13A  shows an operation in which the entire region of each slice image captured by the image sensor  24  is transmitted as it is for all the image capture ranges. 
       FIG. 13B  shows an operation in which a part of the slice image IMGs captured by the image sensor  24  is cropped and the slice image IMGs′ thus cropped is transmitted for at least one image capture range RNG. The data amount of the slice image IMGs′ thus cropped is smaller than that of the slice image IMGs before cropping, thereby reducing the transmission time. 
     The above is the operation of the gating camera  20 . Next, description will be made regarding an advantage thereof. The image capture time of the gating camera  20  can be regarded as the sum total of the exposure time and the transmission time of the slice images for all the image capture ranges. With the gating camera  20 , the data amount of the slice image IMGs to be transmitted from the image sensor  24  to the image processing unit  34  is reduced according to the situation. This allows the transmission time to be reduced, thereby allowing the image capture time of the gating camera  20  to be reduced. 
     In particular, by cropping a part of the slice image, this reduces the size of the slice image. With such an arrangement in which only a necessary portion is cropped and transmitted, this allows the data amount to be reduced. Instead of cropping, such an arrangement may employ pixel binning or pixel thinning so as to reduce the data amount. However, in such a case, this degrades the resolution of the slice image to be input to the image processing unit  34 . Accordingly, this has the potential to cause a problem of degraded precision of object recognition processing in a downstream stage. In contrast, with such an arrangement employing the cropping, this does not involve degradation of the resolution. Accordingly, there is no need for concern regarding degradation of the precision of the object recognition. 
     Next, description will be made regarding a specific example of the control operation with and without cropping. 
     The gating camera  20  is configured to be switchable between a first mode and a second mode. In the first mode, all the slice images IMGs 1  through IMGs N  that correspond to all the image capture ranges RNG 1  through RNG N  are transmitted without cropping. In the second mode, the slice image group IMGs 1  through IMGs Y  that corresponds to the near-distance image capture ranges RNG 1  through RNG Y  are transmitted without cropping. In contrast, the slice image group IMGs Y+1  through IMGs N  that corresponds to the far-distance image capture ranges RNG Y+1  through RNG N  are cropped and transmitted. 
     Judgment of whether or not the mode is to be switched to the second mode is made based on the far-side slice image group IMGs Y+1  through IMGs N  that corresponds to the image capture ranges RNG Y+1  through RNG N , which are farther than a predetermined distance, from among the multiple slice images IMGs 1  through IMGs N  transmitted in the first mode. Specifically, when the far-side slice image group IMGs Y+1  through IMGs N  includes only a single object of interest, the mode is switched to the second mode. In the second mode, a portion including the object of interest is set to the region of interest, and only the portion of interest is cropped and transmitted. 
       FIG. 14  is a flowchart showing an example of the mode control operation of the gating camera  20 . First, the mode is set to the first mode (S 100 ). As described above, in the first mode, all the slice images IMGs 1  through IMGs N  are input to the image processing unit  34  (S 102 ). 
     When the far-side slice image group IMGs Y+1  through IMGs N  includes only a single object of interest (OOI) (YES in S 104 ), the image processing unit  34  switches the gating camera  20  to the second mode (S 106 ). Otherwise (NO in S 104 ), the first mode is maintained, and the flow returns to Step S 102 . 
     For example, in Step S 104 , when the image processing unit  34  detects an object of interest in the far-distance slice image group IMGs, the image processing unit  34  may calculate the position of the object of interest. When judgment is made that there is no object other than the object of interest in the far-distance image capture ranges RNG Y+1  through RNG N , the mode may be switched to the second mode. 
       FIG. 15  is a diagram showing an example of a situation in which the mode is switched to the second mode. The gating camera  20  is mounted on a vehicle  800 . An oncoming vehicle  802  exists in front of the vehicle  800 . The oncoming vehicle  802  is an object of interest that exists in the far-side ranges RNG Y+1  through RNG N . There is no object of interest other than the oncoming vehicle  802  in the far-side ranges RNG Y+1  through RNG N . When the gating camera  20  detects such a situation, the gating camera  20  transits to the second mode. 
     Returning to  FIG. 14 , when the mode is switched to the second mode (S 106 ), the size and the position of the ROI including the object of interest thus detected in Step S 104  are determined. During the second mode, the ROI is cropped for the far-side slice image group IMGs Y+1  through IMGs N . The slice images IMGs Y+1  through IMGs N  each including the region of interest ROI are transmitted. 
     It should be noted that, as described above, even in the second mode, the near-distance slice images IMGs 1  through IMGs Y  are each transmitted in the original size without cropping. 
     During a period in which a first mode returning condition is not satisfied (NO in S 108 ), the second mode is maintained. Conversely, when the first mode returning condition is satisfied (YES in S 108 ), the mode is returned to the first mode S 100 . 
     The first mode returning condition may be the passage of a predetermined period of time. Also, when multiple objects of interest exist in the far-distance image capture ranges RNG Y+1  through RNG N , judgment may be made that the first mode returning condition is fulfilled. Also, when the original object of interest disappears from the far-distance image capture ranges RNG, judgment may be made that the first mode returning condition is fulfilled. 
     Embodiment 3 
       FIG. 16  is a block diagram showing a gating camera  20 A according to an embodiment  3 . In the gating camera  20 A, the illumination apparatus  22  is configured to focus or diffuse the probe light L 1  so as to provide a variable illumination range. The camera controller  32  is configured to be capable of adaptively controlling the illumination range of the illumination apparatus  22  according to a control signal S 4 . 
     When the slice images IMGs to be cropped and transmitted are captured, the camera controller  32  instructs the illumination apparatus  22  to focus the probe light L 1  so as to narrow the illumination range. 
     For example, when the far-distance slice image group through IMGs N  is to be captured in the second mode, the camera controller  32  focuses the probe light L 1  so as to illuminate the probe light L 1  in a concentrated manner to the region of interest. This allows the illuminance of the illumination range to be raised, thereby allowing a clear image to be acquired. 
     The above is the configuration of the gating camera  20 A. Next, description will be made regarding the advantage thereof. 
     In the image capture in the far-side image capture ranges, the amount of attenuation of the probe light L 1  and the reflected light L 2  thereof becomes large. In some cases, this leads to a problem in that slice images IMGs having sufficient brightness cannot be generated in a single exposure. In this case, when image capture is executed for the far-side image capture range, it is necessary to perform exposure multiple times, and multiple slice images acquired for the respective multiple exposures are combined so as to generate a single slice image. With the present embodiment, the probe light L 1  is focused, thereby allowing the slice images IMGs to be generated with increased brightness by a single exposure. With this, the number of exposures to be executed can be reduced. That is to say, this allows the number of transmissions of slice images to be reduced. This allows the image capture time to be shortened. 
     Embodiment 4 
       FIG. 17  is a block diagram showing a gating camera  20 B according to an embodiment 4. In the gating camera  20 B, only the illumination range of the illumination apparatus  22  is controlled. That is to say, the slice image to be transmitted is not cropped. The control of the illumination apparatus  22  is the same as in the embodiment 3. With the gating camera  20 B, this is capable of reducing the number of times exposure is to be performed for the far-side image capture range, thereby allowing a clear slice image to be acquired. 
       FIG. 18  is a block diagram showing an active sensor  70  according to an embodiment 5. The active sensor  70  is configured as a gating camera, ToF camera, LIDAR, or the like. The active sensor  70  includes a light emitting apparatus  72 , a photosensor  74 , and a controller  76 . 
     The light emitting apparatus  72  emits pulsed light multiple times for one instance of sensing. In the present embodiment, the light emitting apparatus  72  provides light emission timing with non-uniform time intervals T INT . The time intervals T INT  may be determined at random for each cycle. Also, the time intervals T INT  may be changed according to a pattern determined beforehand. For example, the time intervals T INT  may be monotonically increased or decreased for each operating period Tc. 
     The output light L 1  of the light emitting apparatus  72  is reflected by the object OBJ, and is incident to the photosensor  74 . The reflected light L 2  has a delay τ with respect to the output light L 1 . Here, τ corresponds to the distance z to the object OBJ, and is represented by the following Expression (1). τ will be referred to as the “round-trip time”. 
       τ=2× z/c    (1)
 
     Here, c represents the speed of light. 
     The exposure timing and the exposure time are controlled so as to allow the photosensor  74  to detect each pulse included in the reflected light L 1  in synchronization with the light emission provided by the light emitting apparatus  72  for every light emission thereof. The light emission timing of the light emitting apparatus  72  and the exposure timing of the photosensor  74  are controlled by the controller  76 . 
     The reflected light L 2  from the object is incident to the photosensor  74  multiple times according to multiple light emissions of the light emitting apparatus  72 . The photosensor  74  integrates the reflected light thus received multiple times, and outputs a signal that corresponds to the integrated value. 
       FIG. 19  is a time chart showing the relation between the light emission timing of the light emitting apparatus  72  and the exposure timing of the photosensor  74 . For example, the time point at which the exposure of the photosensor  74  is started may be set with a predetermined delay time Td from the time point at which the light emitting apparatus  72  starts to emit light. The method for determining the time difference Td may be determined according to the kind and method of the active sensor  70 . For example, the time difference Td may be determined based on the round-trip time τ to an object of interest for image capture. The exposure time Te may be equal to or greater than the light emission time (pulse width) Tp provided by the light emitting apparatus  72 . 
     Each instance of sensing including one light emission of the light emitting apparatus  72  and one exposure of the photosensor may be repeatedly executed with a predetermined period Tc. In this case, the light emission timing (period of time T x  from the start of the period Tc to the light emission) of the light emitting apparatus  72  in the predetermined period Tc may be changed for each sensing. The time interval T INTi  between the i-th light emission timing and the (i+1)-th light emission timing is represented by the following Expression (2). 
         T   INTi   =Tc+T   xi+1   −T   xi    (2)
 
     The above is the configuration of the active sensor  70 . Next, description will be made regarding the operation thereof. 
     In order to clarify the advantages of the active sensor  70 , first, description will be made regarding a comparison technique. In the comparison technique, the light emitting apparatus emits light at uniform time intervals, and exposure of the photosensor is executed at uniform time intervals.  FIG. 20  is an operation waveform diagram of an active sensor according to such a comparison technique. Description will be made below assuming that there is another light source in the vicinity of the active sensor such that it emits pulsed light at a period Tc′ obtained by multiplying or dividing the operating period Tc by an integer. In  FIG. 20 , the light emitted by the other light source is shown as disturbance light L 3 . In this example, description will be made assuming that the light emission period Tc′ of the disturbance light is equal to the operating period Tc of the active sensor. 
     When each pulse of the disturbance light L 3  is included in the exposure period Te, this has an effect on the sensing of the active sensor. In the comparison technique, the light emitting apparatus  72  emits light at a uniform light emission period T INT  (Tc). Accordingly, the exposure is executed at a timing with a uniform interval (Tc). 
     With this, each pulse of the disturbance light L 3  is always included in the corresponding exposure time Te. Accordingly, the effect of the disturbance light L 3  is cumulative, leading to a large error. In  FIG. 20 , the error component is indicated by hatching. 
     Next, description will be made regarding the operation of the active sensor  70  according to the embodiment  5 .  FIG. 21  is an operating waveform diagram of the active sensor  70  shown in  FIG. 18 . 
     As described above, when each pulse of the disturbance light L 3  is included in the exposure period Te, this has an effect on the sensing of the active sensor  70 . With the present embodiment, the light emitting apparatus  72  emits light at non-uniform intervals T INT . Accordingly, the exposure start time point is changed for each operating period Tc. With this, each pulse of the disturbance light L 3  is included in the exposure time or is not included in the exposure time Te. In the example shown in  FIG. 20 , the first pulse of the disturbance light L 3  is detected as a false detection signal. However, the subsequent pulses of the disturbance light L 3  are out of the exposure period, thereby preventing false detection. Accordingly, this allows the effect of the disturbance light L 3  to be reduced, thereby providing high-precision detection. 
     Next, description will be made regarding the usage of the active sensor  70 . As an example, the active sensor  70  is configured as a gating camera. 
       FIG. 22  is a block diagram showing a gating camera  20  according to an example. The gating camera  20  captures images for a plurality of N (N≥2) ranges RNG 1  through RNG N  divided in the depth direction. 
     The gating camera  20  includes an illumination apparatus  22 , an image sensor  24 , a camera controller  26 , and an image processing unit  28 . The illumination apparatus  22  corresponds to the light emitting apparatus  72  shown in  FIG. 18 . The image sensor  24  corresponds to the photosensor  74  shown in  FIG. 18 . The camera controller  26  corresponds to the controller  76  shown in  FIG. 18 . 
     The illumination apparatus  22  illuminates probe light L 1  in front of the vehicle in synchronization with a light emission timing signal S 1  supplied from the camera controller  26 . The probe light L 1  is preferably generated as infrared light. However, the present invention is not restricted to such an arrangement. Also, the probe light L 1  may be visible light having a predetermined wavelength. As described above, the pulses are generated at non-uniform time intervals. 
     The image sensor  24  is configured to support exposure control in synchronization with the exposure timing signal S 2  supplied from the camera controller  26 , and to be capable of generating slice images IMG. The image sensor  24  is sensitive to the same wavelength as that of the probe light L 1 . The image sensor  24  captures images of reflected light (returned light) L 2  reflected by the object OBJ. 
     The camera controller  26  holds the light emission timing and the exposure timing determined for each of the image capture ranges RNG. When image capture is performed for a given image capture range RNG i , the camera controller generates the light emission timing signal S 1  and the exposure timing signal S 2  based on the light emission timing and the exposure timing associated with the corresponding range, and executes image capture. The gating camera  20  is capable of generating multiple slice images IMG 1  through IMG N  that correspond to the multiple ranges RNG 1  through RNG N . The i-th slice image IMG i  includes an object included in the corresponding range RNG i . 
       FIG. 23  is a diagram for explaining the operation of the gating camera  20 .  FIG. 23  shows the operation when the i-th range RNG i  is measured. The illumination apparatus emits light during a light-emitting period τ 1  from the time point t 0  to t 1  in synchronization with the light emission timing signal S 1 . In the upper diagram, a light beam diagram is shown with the horizontal axis as time and with the vertical axis as distance. The distance between the gating camera  20  and the near-distance boundary of the range RNG i  is represented by d MINi . The distance between the gating camera  20  and the far-distance boundary of the range RNG i  is represented by d MAXi . 
     The round-trip time T MINi , which is a period from the departure of light from the illumination apparatus  22  at a given time point, to the arrival of the light at the distance d MINi , up to the return of the reflected light to the image sensor  24 , is represented by T MINi =2×d MINi /c. Here, c represents the speed of light. 
     Similarly, the round-trip time T MAXi , which is a period from the departure of light from the illumination apparatus  22  at a given time point, to the arrival of the light at the distance d MAxi , up to the return of the reflected light to the image sensor  24 , is represented by T MAXi =2×d MAXi /c. 
     When an image of an object OBJ included in the range RNG i , is to be captured, the camera controller  26  generates the exposure timing signal S 2  so as to start the exposure at the time point t 2 =t 0 +T MINi , and so as to end the exposure at the time point t 3 =t 1 +T MAXi . This is a single exposure operation. 
     When the image of the i-th range RNG i  is captured, light emission and exposure are repeatedly executed multiple times, and the measurement results are integrated in the image sensor  24 . 
       FIGS. 24A and 24B  are diagrams for explaining an image acquired by the gating camera  20 .  FIG. 24A  shows an example in which an object (pedestrian) OBJ 1  exists in the range RNG 1 , and an object (vehicle) OBJ 3  exists in the range RNG 3 .  FIG. 24B  shows multiple slice images IMG 1  through IMG 3  acquired in the situation shown in  FIG. 24A . When the slice image IMG 1  is captured, the image sensor is exposed by only the reflected light from the range RNG 1 . Accordingly, the image IMG 1  includes an object image OBJ 1  of the pedestrian OBJ 1 . 
     When the slice image IMG 2  is captured, the image sensor is exposed by the reflected light from the range RNG 2 . Accordingly, the slice image IMG 2  includes no object image. 
     Similarly, when the slice image IMG 3  is captured, the image sensor is exposed to the reflected light from the range RNG 3 . Accordingly, the slice image IMG 3  includes only the object OBJ 3 . As described above, with the gating camera  20 , this arrangement is capable of capturing object images in the form of separate images for the respective ranges. 
     The above is the operation of the gating camera  20 . With such a gating camera in which the illumination apparatus  22  emits light at non-uniform intervals, this is capable of reducing the effects of other pulsed light sources in the vicinity, thereby allowing a clear image to be acquired with a low noise component. 
     Description will be made regarding modifications relating to the embodiment 3. 
     Modification 1 
     The method for changing the time intervals T INT  of pulsed light emission of the light emitting apparatus  72  is not restricted to such an arrangement shown in  FIG. 19 . For example, the operating period Tc may be changed for every cycle while maintaining T x  at a constant value. 
     Modification 2 
     The active sensor  70  is not restricted to such a gating camera. Also, the active sensor  70  may be configured as a TOF (Time Of Flight) camera or LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging). 
       FIG. 25  is a diagram showing an automotive lamp  200  including the gating camera  20  or the active sensor  70  as a built-in component thereof (description will be made below assuming that the automotive lamp  200  includes the gating camera). The automotive lamp  200  includes a housing  210 , an outer lens  220 , a high-beam and low-beam lamp unit  230 H/ 230 L, and the gating camera  20 . The lamp unit  230 H/ 230 L and the gating camera  20  are housed in the housing  210 . 
     It should be noted that a part of the gating camera  20 , e.g., the image sensor  24 , may be arranged as an external component of the automotive lamp  200 , e.g., may be arranged on the back side of a rear-view mirror. 
       FIG. 26  is a block diagram showing the automotive lamp  200  provided with an object identification system  10 . The automotive lamp  200  forms a lamp system  310  together with an in-vehicle ECU  304 . The automotive lamp  200  includes a light source  202 , a lighting circuit  204 , and an optical system  206 . Furthermore, the automotive lamp  200  includes the object identification system  10 . The object identification system  10  includes the gating camera  20  (or active sensor  70 ) and a calculation processing device  40 . 
     The calculation processing device  40  is configured to identify the kind of an object based on multiple slice images IMG 1  through IMG N  that correspond to the multiple range RNG 1  through RNG N  acquired by the gating camera  20 . The calculation processing device  40  is provided with a classifier implemented based on a prediction model generated by machine learning. The algorithm employed by the classifier is not restricted in particular. Examples of the algorithms that can be employed include You Only Look Once (YOLO), Single Shot MultiBox Detector (SSD), Region-based Convolutional Neural Network (R-CNN), Spatial Pyramid Pooling (SPPnet), Faster R-CNN, Deconvolution-SSD (DSSD), Mask R-CNN, etc. Also, other algorithms that will be developed in the future may be employed. 
     The calculation processing device  40  may be configured as a combination of a processor (hardware component) such as a Central Processing Unit (CPU), Micro Processing Unit (MPU), microcontroller, or the like, and a software program to be executed by the processor (hardware component). Also, the calculation processing device  40  may be configured as a combination of multiple processors. Alternatively, the calculation processing device  40  may be configured as a hardware component alone. 
     Also, the information with respect to the object OBJ detected by the object identification system  10  may be used to support the light distribution control operation of the automotive lamp  200 . Specifically, a lamp ECU  208  generates a suitable light distribution pattern based on the information with respect to the kind of the object OBJ and the position thereof generated by the object identification system  10 . The lighting circuit  204  and the optical system  206  operate so as to provide the light distribution pattern generated by the lamp ECU  208 . 
     The information with respect to the object OBJ thus detected by the calculation processing device  40  may be transmitted to the in-vehicle ECU  304 . The in-vehicle ECU  304  may use this information to provide autonomous driving or driving assistance. 
     Description has been made regarding the present invention with reference to the embodiments using specific terms. However, the above-described embodiments show only an aspect of the mechanisms and applications of the present invention. Rather, various modifications and various changes in the layout can be made without departing from the spirit and scope of the present invention defined in appended claims. 
     CLAUSES DESCRIBING APPLICABILITY 
     11. A gating camera comprising: 
     an illumination apparatus structured to illuminate probe light; 
     an image sensor; 
     a camera controller structured to control a timing at which the illumination apparatus illuminates the probe light and a timing at which the image sensor is exposed, such that the image sensor outputs a slice image for each of image capture ranges divided in the depth direction while changing the image capture range, and such that each slice image includes only an object included in the corresponding image capture range; and 
     an image processing unit structured to receive the slice images from the image sensor, and to process the slice images, 
     wherein the camera controller is structured to be capable of adaptively controlling a data amount of the slice images transmitted from the image sensor to the image processing unit. 
     12. The gating camera according to clause 11, wherein the camera controller is structured to crop a part of the slice image so as to reduce a size of the slice image. 
     13. The gating camera according to clause 12, wherein a slice image group that corresponds to an image capture range group that is nearer than a predetermined distance is always transmitted without cropping, 
     and wherein, whether or not the slice image is to be cropped is controlled for a slice image group that corresponds to an image capture range group that is farther than the predetermined distance. 
     14. The gating camera according to clause 12, wherein the plurality of the slice images that correspond to the plurality of image capture ranges are transmitted without cropping, 
     and wherein, whether or not a plurality of subsequent slice images are to be cropped is determined based on the plurality of uncropped slice images. 
     15. The gating camera according to clause 12, wherein, in a first mode, all slice images that correspond to all image capture ranges are transmitted without cropping, 
     wherein, when a far-side slice image group that corresponds to an image capture range group that is farther than a predetermined distance transmitted in the first mode includes only a single object of interest, a mode is switched to a second mode, 
     and wherein, in the second mode, the far-side slice image group is transmitted after a region of interest thereof including the object of interest is cropped. 
     16. The gating camera according to clause 15, wherein the illumination apparatus is structured to be capable of focusing and diffusing the probe light so as to provide a variable illumination range, 
     and wherein, when a slice image is to be transmitted with cropping, the camera controller instructs the illumination apparatus to focus the probe light. 
     17. A gating camera comprising: an illumination apparatus structured to illuminate probe light, and to be capable of focusing and diffusing the probe light so as to provide a variable illumination range; 
     an image sensor; 
     a camera controller structured to control a timing at which the illumination apparatus illuminates the probe light and a timing at which the image sensor is exposed, such that the image sensor outputs a slice image for each of image capture ranges divided in the depth direction while changing the image capture range, and such that each slice image includes only an object included in the corresponding image capture range; and 
     an image processing unit structured to receive the slice images from the image sensor, and to process the slice images, 
     wherein the camera controller controls an illumination range of the illumination apparatus based on detection results obtained by the image processing unit. 
     18. The gating camera according to clause 7, wherein, in a first mode, the probe light is illuminated to an entire illumination range, 
     wherein, in the first mode, when the image processing unit detects an object of interest in the slice image that corresponds to a predetermined image capture range, the first mode is switched to a second mode, 
     and wherein, in the second mode, when an image is captured for the predetermined image capture range, the probe light is illuminated to a region of interest including the object of interest. 
     19. An automobile comprising: 
     the gating camera according to clause 11; and 
     a calculation processing device structured to process an output of the gating camera. 
     20. An automotive lamp comprising the gating camera according to clause 11. 
     21. An active sensor comprising: 
     a light emitting apparatus structured to emit a pulsed light multiple times at non-uniform time intervals; and 
     a photosensor structured to detect reflected light from an object at a timing in synchronization with light emission of the light emitting apparatus for every light emission. 
     22. The active sensor according to clause 21, wherein one instance of sensing including a single light emission of the light emitting apparatus and a single exposure of the photosensor is repeatedly executed with a predetermined cycle, 
     and wherein the light emission timing of the light emitting apparatus in the predetermined cycle is changed for each sensing. 
     23. The active sensor according to clause 21, wherein the active sensor is structured as a gating camera structured to change a time difference between light emission and image capture for each of ranges divided in the depth direction, so as to be capable of acquiring a plurality of images that correspond to the plurality of ranges. 
     24. The active sensor according to clause 21, structured as a Time Of Flight (TOF) camera. 
     25. The active sensor according to clause 21, structured as a LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging). 
     26. An object identification system comprising: 
     the active sensor according to clause 21; and 
     a calculation processing device structured to be capable of identifying a kind of an object based on an image acquired by the active sensor. 
     27. An automotive lamp comprising the object identification system according to clause 26. 
     28. A vehicle comprising the object identification system according to clause 26.