JP2012073823A - Device for detecting pedestrian - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a pedestrian with high accuracy even on a place other than a crosswalk with a low cost structure capable of using a low cost camera sensitive to a visible light region as an on-vehicle camera.SOLUTION: A change area initially detecting part 4 initially detects, as a change area, a image portion appearing on a photographic image by a camera 2 attached on a vehicle 1. A detection window setting part 5 and/or a change area updating part 6 initially sets a plurality of detection windows around the change area of the photographic image, detects a new image portion newly appearing on any of the plurality of detection windows as a new change area and updates the change area, sets a plurality of new detection windows around the updated change area of a new photographic image to be obtained then. Thus, the detection window setting part 5 and/or the change area updating part 6 repeats these processes to detect motion specific to a pedestrian, detecting a pedestrian even on a place other than a crosswalk with high accuracy by using a low cost camera sensitive to a visible light region.

Description

  The present invention relates to a pedestrian detection device that detects a pedestrian from a photographed image around a vehicle (for example, forward) of a camera mounted on the vehicle. Specifically, the detection accuracy is improved at low cost.

  In general, the effective lighting range of a vehicle (automobile) headlight is limited, and the range is affected by the weather, etc., so that the pedestrians illuminated by the headlight are used when driving the vehicle at night. Visual recognition is not easy, and pedestrians may suddenly appear and approach or cross.

  In order to achieve safe driving in such a case, it is conventionally considered that an infrared camera is mounted on a vehicle and the pedestrian is detected by detecting infrared rays emitted by the pedestrian, but the infrared camera is expensive, The vehicle cost is significantly increased.

  Therefore, an inexpensive camera that can be used in the visible light region, such as a normal CCD monocular camera, is mounted on the vehicle, and a vertically long image that moves from the difference between the two frames taken in front of and behind the vehicle that the camera takes is displayed. It has been proposed to detect as a pedestrian (person) (see, for example, Patent Document 1 (paragraphs [0003]-[0006], [0009]-[0012], FIG. 1)).

Japanese Patent Laid-Open No. 11-31230

  In the case of the detection device described in Patent Document 1, although an inexpensive camera in the visible light region can be used, the cost is low, but a vertically long image may not be a pedestrian (person). If only the toes are illuminated by the headlight, a pedestrian does not always have a vertically long image. For this reason, the detection accuracy of pedestrians is low, and there are a number of vertically long images such as roadside signs and signs other than pedestrian crossings, and it is not easy to distinguish pedestrians from them.

  An object of the present invention is to accurately detect a pedestrian even in a place other than a pedestrian crossing by an inexpensive (low cost) configuration in which an inexpensive camera in the visible light region can be used as a camera mounted on a vehicle. .

  In order to achieve the above object, a pedestrian detection device of the present invention is a pedestrian detection device that detects a pedestrian from a captured image around a vehicle of a camera mounted on a vehicle, and appears in the captured image of the camera. Initial setting means for initial detection of the image location as a change area, and initial setting of a plurality of detection windows around the change area of the captured image obtained thereafter, and an image newly appearing in any of the detection windows Detecting a location as the change area, updating the change area, and repeatedly setting the detection windows around the updated change area of the captured image obtained thereafter, repeatedly to any of the detection windows It is characterized by comprising detection means for detecting a pedestrian by detecting a pedestrian-specific motion from the repeated occurrence of a new image location (claim 1).

  According to the first aspect of the present invention, since a pedestrian is detected from a difference between captured images around the vehicle whose time of the camera mounted on the vehicle fluctuates, an inexpensive camera in the visible light region can be used. (Low cost) configuration.

  For example, when paying attention to the legs of the pedestrian, the left foot and the right foot alternately move forward (forward direction), and when the pedestrian moves forward and approaches the vehicle at night or the like, the left foot or right foot ( One foot) suddenly appears in the photographed image in the headlight of the vehicle.

  Further, the pedestrian moves forward by moving the other foot (right foot or left foot) forward with one foot as an axial foot, and then moves forward one foot and the other foot alternately. Therefore, the front foot that newly appears in the captured image of the camera alternately changes from one foot to the other foot.

  Then, the initial setting means initially detects an image portion of one foot that appears first, for example, the left foot as a change area, and when the detection windows are initially set on the left and right sides of the change area that is the periphery of the image area, The right foot, which is the other foot, appears in the right detection window.

  Furthermore, when the change area is changed to the image location of the right foot that has appeared by the detection means, and the detection window is set on both the left and right sides of the changed change area, the left foot appears in the detection window on the left side of the subsequent captured image, and changes. If you change the area again to the location of the image of the left foot that appeared, and set detection windows on the left and right sides of the changed area, the right foot appears in the detection window on the right side of the captured image, and the left and right feet alternate. Based on the movement specific to the pedestrian that moves forward, new front legs appear alternately on the left and right detection windows of the changed change area in the same manner, and the detection windows on the left and right sides of the change area always appear. A new image location appears on either one (one side).

  In addition, when a pedestrian moves forward and crosses the front of the vehicle in the left-right direction, if the pedestrian moves forward and crosses based on the pedestrian-specific motion of alternately moving the left and right feet forward, Then, the left foot and the right foot of the pedestrian appear alternately so as to advance in the moving direction. Then, when the image area of the appearing foot is detected / updated as the change area and the detection windows are set on both the left and right sides of the change area, the forward foot appears in the detection window on the moving direction side in the subsequent image. . Therefore, also in this case, a new image location always appears in one (one side) of the detection windows on the left and right sides of the change area.

  For obstacles such as vehicles that do not move the left and right feet forward alternately and roadside signs / signs, the same image that appears gradually increases in the captured image. It cannot be set, and a new image location does not appear in either one (one side) of the detection windows on the left and right sides of the change area.

  Accordingly, the detection means, for example, focusing on the pedestrian's legs, repeats the appearance of a new image location in one of the detection windows on the left and right sides of the change area (one side), whether or not there is a crosswalk, etc. Regardless, it is possible to detect a pedestrian with high accuracy by detecting a pedestrian-specific movement in which left and right feet are alternately put forward.

It is a block diagram of one embodiment of a pedestrian detection device of the present invention. It is explanatory drawing of the photography example of a pedestrian. It is explanatory drawing of a detection of the pedestrian who moves forward toward a vehicle. It is a flowchart for operation | movement description of the pedestrian detection apparatus of FIG. It is explanatory drawing of the detection of the pedestrian who moves forward across the front of a vehicle.

  An embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows a configuration of an example of a pedestrian detection device according to the present invention provided in a vehicle 1, and the vehicle 1 outputs a captured image taken in front of the vehicle as a captured image around the vehicle, for example, with a frame period of 1/30 seconds. A camera 2 is mounted. The camera 2 is an inexpensive camera for photographing in the visible light region, and is specifically a monochrome or color monocular CCD camera.

  Reference numeral 3 denotes a headlight (headlight) of the vehicle 1 that is turned on by a driver's operation or automatically at night or the like, and is provided on the front left and right of the vehicle 1 to illuminate the front of the vehicle 1 and Also doubles. FIG. 2 shows an example of front irradiation of the headlight 3 of the vehicle 1 traveling in the direction of the arrow line a, the two-dot broken line in the figure is the left and right irradiation range of the headlight 3, and P is indicated by the arrow line b. A pedestrian forward to move forward. In this case, the portion farther from the irradiation range of the headlight 3 of the pedestrian P is dark as shown by the oblique lines in the figure and is not photographed by the camera 2. On the other hand, the part within the irradiation range of the headlight 3 of the pedestrian P is photographed by the camera 2, and the part closer to the vehicle 1 is photographed brighter (higher brightness).

  The pedestrian P moves forward (walks) with both left and right feet alternately forward, and at that time, both hands also move back and forth alternately, opposite to both feet. Moreover, the head fluctuates up and down. These movements are pedestrian-specific movements.

  FIG. 3A is a schematic view of a situation in which the pedestrian P moves forward at night as shown in FIG. 2 and the pedestrian P approaches the vehicle 1 from the front. In this case, the pedestrian P When the vehicle 1 and the pedestrian P approach a certain distance, one leg (in this case, the right leg) that comes out in front of the pedestrian P enters the irradiation range of the headlight 3. As shown in FIG. 3B, one foot of the pedestrian P suddenly appears as an image of reflected light in the captured image of the camera 2, and then in FIG. 3C. As shown in the figure, the other foot (the right foot r marked with ● in this case) appears in the captured image as a reflected light image brighter than the one foot, and thereafter, as shown in FIGS. 3 (d) and 3 (e). In addition, one foot and the other foot appear alternately in the captured image as a brighter reflected light image. This phenomenon appears similarly in both the left and right hands when attention is paid to the arm portion of the pedestrian P. As for the head, when the pedestrian P walks, the head moves up and down and at least its upper end moves up and down from the upper end of the irradiation range of the headlight 3 and appears periodically in the captured image.

  Reference numerals 4, 5, 6, and 7 in FIG. 1 denote a change region initial detection unit, a detection window setting unit, a change region update unit, and a pedestrian detection unit formed by a microcomputer program (software processing). The unit 4 forms the initial setting means of the present invention, and the detection window setting unit 5, the change area update unit 6, and the pedestrian detection unit 7 form the detection means of the present invention.

  When attention is paid to the legs of the pedestrian P, the change area initial detection unit 4 determines the difference in luminance of the captured image of each frame of the camera 2 if the luminance of each part of the captured image of the camera 2 is equal to or less than a certain value. Repeat the calculation. At this time, when one foot that the pedestrian P is moving forward enters the irradiation range, the time-series captured images of a plurality of frames in time series gradually increase in the portion that becomes bright due to the reflection of the one foot. , It becomes maximum when the one foot has landed and comes out the foremost. When the luminance of a portion having a size larger than a reference area set in anticipation of the size of the local maximum becomes equal to or higher than a threshold value, the change area detection unit 4 detects the new foot image of the pedestrian P. 3 (b), in which the image location is initially detected as a rectangular or circular change area A set in advance. The detection window setting unit 5 initially sets a rectangular or circular detection window B having a preset size on the left and right sides of the change area A that is the periphery of the change area A that is initially detected. A detection frame constituted by the detection window B is formed (FIG. 3C). Note that tn to tn + 3 in FIGS. 3B to 3E indicate fields in time order in which the appearance of a new foot is detected.

  The change area update unit 6 superimposes the detection frame on the subsequent captured image of the camera 2 and monitors the change in the luminance of the left and right detection windows B. When the pedestrian P first appears with the first foot as an axis and the other foot is moved forward, the size and the like of each detection window B are set so as to reliably capture the reflected image of the foot. Therefore, the luminance of one of the detection windows B becomes brighter than the threshold value by the appearance of the reflection image of the other foot that has been put forward (here, detection indicated by a circle in FIG. 3C). Window B becomes brighter). From the change in brightness of the detection window B, the change area update unit 6 detects a newly appearing image location as the change area A, and sets the detection window B in which the reflected image of the other foot appears as the change area A. Then, the change area A is updated (FIG. 3D).

  Further, the detection window B is set to the left and right of the updated change area A by the detection window setting section 5 (FIG. 3D), and the change area update section 6 adds the detection frame to the captured image of the camera 2 thereafter. Are superposed on the left and right detection windows B to monitor the change in luminance. Then, when the advancing pedestrian P puts one foot forward with the other foot as an axis, the corresponding detection window B (here, the detection window on the right side) is displayed by the appearance of the reflected image of the one foot that has been put forward. The brightness of B) becomes brighter than the threshold value (detection window marked with a circle in FIG. 3D). From the change in brightness of the detection window B, the change area update unit 6 detects a newly appearing image location as the change area A, and sets the detection window B in which the reflected image of one foot appears as the change area A. Then, the change area A is updated, and the detection window setting unit 5 sets the detection windows B on the left and right sides thereof (FIG. 3 (e)). Then, the change area updating unit 6 superimposes the detection frame on the subsequent captured image of the camera 2 to monitor the change in luminance of the left and right detection windows B, and then reflects the other foot that has been put forward. The appearance of the image is detected (FIG. 3E), and the change area A is updated.

  As for the pedestrian P moving forward toward the vehicle 1 by the same repetition, the left and right feet alternately move forward and the portion becomes brighter, which is apparent from FIGS. 3B to 3E. Thus, the appearance of new feet is detected alternately in the left and right detection windows B of the set change area A. In other words, a motion peculiar to the pedestrian P can be detected by detecting the appearance of a new foot in one of the left and right detection windows B.

  In addition, if it is not a pedestrian P but an oncoming vehicle, a signboard, etc., the phenomenon that the left and right feet described above alternately move forward and the part becomes brighter does not occur, and the change area A is not detected at all, Even if it is detected, a new change area A is not detected in the left and right detection windows B.

  And the pedestrian detection part 7 of FIG. 1 detects the above-mentioned movement specific to the pedestrian P from the detection of the appearance of the reflected image of the new foot of the change area update part 6, and the update of the change area A accompanying it. The pedestrian P is detected with high accuracy. Further, the notification unit 8 in FIG. 1 notifies the driver of the presence of the pedestrian P with an alarm sound or display based on the detection result of the pedestrian detection unit 7, and alerts the driver.

  FIG. 4 shows an outline of the above-described pedestrian detection procedure by the change region initial detection unit 4, the detection window setting unit 5, the change region update unit 6, and the pedestrian detection unit 7, and when a new image location appears in the captured image. Then, it is initially detected as a change area A (YES in step S1), detection windows B are set on the left and right (step S2), and a new image location appears in any of the detection windows B (YES in step S3). ), The image location is updated to the change area A (step S4), and when the motion peculiar to the pedestrian P is detected from the repetition, the step S5 is passed through YES to notify the detection of the pedestrian P (step S6). . In step S3, when a new image location does not appear in any of the detection windows B, or when an image location appears in both detection windows B, step S3 is passed through NO and returns to step S1. In S5, if pedestrian P is not detected, step S5 is passed by NO and returns to step S1.

  Next, even when the pedestrian P crosses the front of the vehicle 1, the pedestrian P can be detected in the same manner as described above.

  FIG. 5 (a) schematically illustrates a situation in which a pedestrian P walks across the front of the vehicle 1 moving forward as indicated by an arrow line c from the right to the left as indicated by an arrow line d. When attention is paid to the leg of the pedestrian P, the vehicle 1 and the pedestrian P approach to a certain distance, and one foot (here, left foot) that comes out in front of the pedestrian P is within the irradiation range of the headlight 3. As shown in FIG. 5B, one foot of the pedestrian P suddenly appears as an image of reflected light in the captured image of the camera 2 and the change area A is initially set. Is done. Next, as shown in FIG. 5 (c), one of the detection windows B set on the left and right of the change area A with the other foot (here, the right foot r marked with ●) appearing forward appears in the photographed image. On the other hand, that is, a bright reflected light image of the other foot appears in the detection window B in the direction in which the pedestrian P moves forward (detection window marked with a circle in FIG. 5C). Thereafter, as shown in FIGS. 5D and 5E, after that, one foot and the other foot alternately move forward, and the pedestrian P crosses the front of the vehicle 1 to thereby change the region A. The detection frame formed by the left and right detection windows B moves from right to left according to the movement of the pedestrian P, and the image of the bright reflected light of the new foot is surely displayed in the detection window B in the direction in which the pedestrian P moves forward. A position appears. Note that tn to tn + 3 in FIGS. 5B to 5E indicate fields in time order in which the appearance of a new foot is detected.

  Therefore, even when the pedestrian P crosses the front of the vehicle 1, the change region set by the configuration of the change region initial detection unit 4, the detection window setting unit 5, the change region update unit 6, and the pedestrian detection unit 7 is set. By detecting the appearance of a new foot in one of the left and right detection windows B of A, it is possible to detect the pedestrian P and accurately recognize the pedestrian P.

  As described above, in the case of the present embodiment, an inexpensive camera in the visible light region is used in order to detect the pedestrian P from the difference between the captured images around the vehicle where the time of the camera 2 mounted on the vehicle 1 varies. The pedestrian P can be detected with an inexpensive (low cost) configuration. At that time, when attention is paid to the legs of the pedestrian P, the detection windows on the left and right sides of the change area A are configured by the configuration of the change area initial detection unit 4, the detection window setting unit 5, the change region update unit 6, and the pedestrian detection unit 7. Walking by detecting the peculiar movement of pedestrians that alternately put the left and right feet forward, regardless of the presence or absence of a pedestrian crossing, from the repeated occurrence of a new image location on either side (one side) of B The person P can be detected with high accuracy.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit thereof. For example, the movement of the legs of the pedestrian P Instead of detecting and monitoring the movement of the arm part, the left and right arms move alternately forward, so by detecting the appearance of a new arm in one of the left and right detection windows of the set change area It is also possible to detect a pedestrian-specific motion and recognize the pedestrian with high accuracy in the same manner as in the above embodiment. Note that the leg portion and the arm portion are distinguished from each other by, for example, the change region initial detection unit 4 and the change region update unit 6 in FIG. It can be detected.

  Further, the head of the pedestrian P moves up and down by walking, and at least the upper end of the pedestrian moves up and down from the upper end of the headlight irradiation range. Detecting and initializing a plurality of detection windows around it, detecting and updating an image part newly appearing in any of the detection windows according to the movement of the head as a change area, and then a captured image obtained Repeatedly setting each detection window around the updated change area of the pedestrian, and detecting a pedestrian-specific motion from the repeated occurrence of a new image location in any of the detection windows. May be detected with high accuracy.

  Next, the present invention has an advantage that the detection accuracy is extremely improved by applying the headlight to the night pedestrian detection using the camera lighting so that an unnecessary image (noise image) is not included in the captured image. Of course, the present invention can also be applied to detection of pedestrians in the daytime and the like that do not require illumination for camera photography.

  Next, the camera 2 may be mounted on the rear part of the vehicle 1 so as to photograph the rear of the vehicle. In this case, if the camera 2 is applied to detection of a pedestrian at night, the light source for illumination is also provided together with the camera 2. It is mounted on the vehicle 1.

  Next, the configuration of the change region initial detection unit 4, the detection window setting unit 5, the change region update unit 6, the pedestrian detection unit 7 and the like may be any and the notification method of the notification unit 8 may be any. May be. Furthermore, based on the detection of the pedestrian P of the pedestrian detection part 7, you may make it automatically control driving | running | working of the vehicle 1 so that the pedestrian P may be avoided.

  The present invention can be applied to detection of pedestrians in various vehicles.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Camera 4 Change area initial detection part 5 Detection window setting part 6 Change area update part 7 Pedestrian detection part A Change area B Detection window P Pedestrian

Claims (1)

A pedestrian detection device for detecting a pedestrian from a photographed image around a vehicle of a camera mounted on a vehicle,
An initial setting means for initial detection of an image portion appearing in the captured image of the camera as a change area, and initial setting a plurality of detection windows around the change area of the captured image obtained thereafter;
The image area newly appearing in any of the detection windows is detected as the change area, the change area is updated, and the detection windows are set around the updated change area of the captured image obtained thereafter. And a detecting means for detecting a pedestrian by detecting a pedestrian-specific motion from the repeated occurrence of a new image location in any of the detection windows. Person detection device.

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