(19) Japanese Patent Office (JP)
`(12) Kokai Unexamined Patent Application Bulletin (A)
`(11) Laid Open Patent Application No.
`
`6-124340
`(43) Publication Date
`
`May 6, 1994
`Number of Claims
`
`5
`
`Number of Pages
`
`16
`
`Examination Request
`
`not yet made
`
`
`items of data to be handled is greatly reduced, the
`processing steps become fast, and extraction of the
`features of the object under scrutiny can be realized at
`high speed.
`
`(FIG. 1)
`
`
`
`
`
`
`
`(54)
`
`[Title of the Invention] Vehicle Image Processing Device
`
`(57) [Abstract]
`[Problem] To provide a vehicle image processing device
`that performs suitable image processing and can be
`practically realized for a vehicle.
`[Configuration] A vehicle image processing device that
`comprises a distance measurement means 66 that
`detects information about the distance and direction to an
`object outside the vehicle, an assessment means 67 that
`decides upon an image processing method based on the
`measurement results, and an image processing means
`69 that, based on the above set image processing
`method, performs image processing on the image
`detected by an image sensor 68. The image processing
`method is, for example, processing that decides upon a
`region on which to perform image processing, processing
`that decides upon an object on which to perform image
`processing,
`and
`processing
`that
`enlarges/reduces/direction-converts a specified object in
`an image. With the above configuration, extraction
`processing is done on image information focusing on an
`object of scrutiny as the target, so that the range in which
`data processing is performed is limited, the number of
`
`Translation by Patent Translations Inc. 1-800-844-0494 mail@PatentTranslations.com
`
`FI
`
`
`Tech. Indic.
`
`
`
`Continued on the last
`page
`
`000003997
`NISSAN MOTOR CO.,LTD.
`2 Takaracho, Kanagawa-ku,
`Yokohama-shi, Kanagawa-ken
`YAMAMURA, Tomohiro
`NISSAN MOTOR CO.,LTD.
`2 Takaracho, Kanagawa-ku,
`Yokohama-shi, Kanagawa-ken
`SATOU, Hiroshi
`NISSAN MOTOR CO.,LTD.
`2 Takaracho, Kanagawa-ku,
`Yokohama-shi, Kanagawa-ken
`Patent Attorney, NAKAMURA,
`Junnosuke (and one more person)
`
`
`
`
`(51)
`
`
`Int. Cl.5
`G06F 15/62
`
`G01C 21/00
`G01S 13/86
` 13/93
`
`Identification Code
`380
`415
`
`
`
`N
`
`N
`
`(21) Application No.:
`
`5-138145
`
`
`Internal File No.
`9287-5L
`9287-5L
`
`7015-5J
`7015-5J
`
`(71)
`
`Applicant:
`
`(22) Application Date:
`
`June 10, 1993
`
`(72)
`
`Inventor:
`
`(31) Number assigned to
`priority application:
`
`4-193993
`
`(72)
`
`Inventor:
`
`(32) Date of filing of priority
`application:
`(33) Country in which
`priority application
`was filed:
`
`
`
`
`July 21, 1992
`
`Japan
`
`(74)
`
`
`
`
`
`
`
`Agent:
`
`
`
`
`
`
`
`IPR2013-00419 - Substitute Ex. 1013
`Toyota Motor Corp., Petitioner
`
`1
`
`

`
`(2)
`
`JP-06-124340-A
`
`
`
`[Claims]
`[Claim 1] A vehicle image processing device characterized by
`comprising:
`an image sensor that is carried on the vehicle and into which is
`input image information on the vehicle surroundings;
`a distance measurement means that determines information on
`the distance and direction to a single object or a plurality of
`objects present outside the vehicle;
`an assessment means that assesses and sets an image
`processing method based on the distance and direction
`information; and
`an image processing means that, based on the image
`processing method set by the assessment means, performs
`image processing on the image information determined by the
`image sensor.
`[Claim 2] The vehicle image processing device recited in claim
`1, characterized in that the assessment means assesses and
`sets an image processing method including at least one type of
`processing among: processing to decide upon the region on
`which to perform image processing, processing to decide upon
`the object on which to perform image processing, and
`processing
`to enlarge/reduce/direction-convert a specified
`object in an image.
`[Claim 3] The vehicle image processing device recited in claim
`1,
`characterized
`in
`that
`the
`image
`sensor
`enlarges/reduces/direction-converts a specified object in an
`image
`according
`to
`the
`enlargement/reduction/direction-conversion processing that is
`set by the assessment means.
`[Claim 4] The vehicle image processing device recited in claim
`2 or claim 3, characterized by comprising a measurement
`means that detects the travel state of one’s own vehicle,
`wherein the assessment means decides upon the object on
`which to perform image processing, according to the detection
`results of the measurement means.
`[Claim 5] A vehicle image processing device characterized by
`comprising:
`a reflecting body detection means that detects the distance and
`direction from one’s own vehicle to a reflecting body by emitting
`electromagnetic waves in the direction of travel of one’s own
`vehicle while sweeping a prescribed angle range, receiving the
`reflected wave from the reflecting body, and calculating the
`distance to the reflecting body based on the propagation delay
`time from emission to reception of the electromagnetic wave at
`prescribed sweep angles;
`an image pickup means that images the scenery to the front in
`the direction of travel of one’s own vehicle;
`an image recognition means that processes the image to the
`front of the vehicle imaged by the image pickup means and
`detects preceding vehicles that are present ahead;
`an image processing region setting means that sets the image
`processing region in the image recognition means according to
`the distance and direction detected from the reflecting body
`detection means; and
`a preceding vehicle position output means that outputs the
`distance or direction, or both, to the reflecting body that is
`recognized as a preceding vehicle by the image processing
`recognition means.
`[Detailed Description of the Invention]
`[0001]
`[Field of Industrial Application] This invention relates to a
`vehicle
`image processing device
`that
`recognizes
`the
`environment around the vehicle. Such a vehicle image
`processing device is used, for example, in a preceding vehicle
`detection device to be applied in a vehicle automatic travel
`Translation by Patent Translations Inc. 1-800-844-0494 mail@PatentTranslations.com
`
`control device or a warning device for approaching another
`vehicle, or the like; that is to say, it is used in a device that
`detects the position of a preceding vehicle that is traveling
`ahead of one’s own vehicle.
`[0002]
`[Prior Art] Devices for preceding vehicle image processing
`include, for example those shown in FIG. 14. In FIG. 14, (a) is a
`vehicle image processing device, which uses one image sensor
`to take in information in as wide a range as possible around the
`vehicle, and which recognizes the information. And (b) is a
`vehicle image processing device that uses two image sensors,
`which are set up at a prescribed angle and distance, and
`extracts features, and the distance and direction to an object,
`from the parallax between such information.
`[0003]
`[Problems to Be Solved by the Invention] In a conventional
`vehicle image processing device such as above, there have
`been problems such as the following. Namely, there have been
`problems in that:
`(1) because the image of an object present in the distance will
`be small, it is difficult to extract its features;
`(2) because the entire image that is taken in is processed, the
`volume of information is large; this makes the processing
`difficult and slows the processing down, and because the size
`of the processing device is large, it is difficult to use it as vehicle
`equipment;
`(3) because the method of image processing cannot be freely
`changed, only specified information can be obtained;
`(4) in addition, because it is impossible to accurately measure
`the distance to an object in a vehicle that is traveling, even if
`image information is obtained, it cannot be used effectively for
`warning the driver or for vehicle travel control.
`[0004] An object of the present invention, which was devised in
`order to solve the problems of the prior art as described above,
`is to provide a vehicle image processing device that can
`perform appropriate image processing and can be practically
`realized for a vehicle.
`[0005]
`[Means for Solving the Problems] In order to achieve the
`object described above, the present invention is configured as
`recited in the claims. That is to say, the invention recited in
`claim 1 comprises an image sensor that is carried on the
`vehicle and into which is input image information on the vehicle
`surroundings; a distance measurement means that determines
`information on the distance and direction to a single object or a
`plurality of objects present outside the vehicle; an assessment
`means that assesses and sets an image processing method
`based on the distance and direction information; and an image
`processing means that performs image processing on the
`above image information determined by the image sensor,
`based on the image processing method set by the assessment
`means. The assessment means, for example as recited in claim
`2, assesses and sets an image processing method including at
`least one type of processing among: processing to decide upon
`the region on which to perform image processing, processing to
`decide upon the object on which to perform image processing,
`and processing to enlarge/reduce/direction-convert a specified
`object in an image. Furthermore, the image sensor above, for
`example
`as
`recited
`in
`claim
`3
`enlarges/reduces/direction-converts a specified object in an
`image
`according
`to
`the
`enlargement/reduction/direction-conversion processing that is
`
`
`
`
`
`2
`
`

`
`(3)
`
`JP-06-124340-A
`
`
`
`set by the assessment means. Furthermore, the invention
`reflected by the object and return. Note that, if the laser light
`recited in claim 4 is one that, in addition to the configuration
`that is emitted is scanned vertically and horizontally, the
`described above, is configured to comprise a measurement
`distance in each direction can be measured, so distance and
`means that detects the travel state of one’s own vehicle and to
`direction information can be obtained. Furthermore, likewise [a
`decide upon the object on which the assessment means
`device] that uses radio waves or ultrasound waves can be
`performs image processing according to the detection results of
`realized with essentially the same configuration. Furthermore,
`the measurement means. Furthermore, the invention recited in
`the assessment means 61 is a means that assesses and sets
`claim 5 is one that shows the specific configuration of a case in
`the image processing method based on the measurement
`which the above vehicle image processing device is applied to
`results of the distance measurement means 60. Note that the
`a preceding vehicle detection device.
`above image processing method refers to, in this working
`[0006]
`example, processing to decide upon the region in which image
`[Operation] As described above, in the present invention, the
`processing is to be performed. Furthermore, the image sensor
`assessment means decides upon the image processing
`62 is a means that inputs the image information on the
`method based on the measurement results of the distance
`surroundings on the vehicle; for example, it is a video camera
`measurement means. This image processing method refers to,
`that uses CCDs. Furthermore, the image processing means 63
`for example as recited in claim 2, processing to decide upon the
`is for example a means that causes pattern recognition to be
`region on which to perform image processing, processing to
`performed. This image processing means 63 and the above
`decide upon the object on which to perform image processing,
`assessment means 61 can be constituted by a computer, for
`and processing to enlarge/reduce/direction-convert a specified
`example. Note that, S1 is a distance and direction signal, S2 is
`object in an image. Furthermore, the image processing means
`an image signal, S3 is an assessment signal, and S4 is a
`feature extraction signal.
`performs image processing based on the above set image
`[0008] Next, FIG. 2 is a diagram that shows the positional
`processing method. Accordingly, by processing with a focus on
`extracting
`image
`information
`targeting
`important objects
`relationship between the vehicle and the object outside the
`requiring image processing, such as objects that block the
`vehicle; (a) is the top view, and (b) is the side view. In FIG. 2, 64
`travel of the vehicle, the range in which data processing is
`is the vehicle, and 65 is the object outside the vehicle.
`performed by the image processing means is limited, so the
`Furthermore, FIG. 3 is a chart listing an example of distance
`number of data items to handle is greatly reduced and the
`measurement results, and FIG. 4 is a flowchart showing the
`processing step is speeded up, making it possible to realize the
`processing procedure in the device in FIG. 1. In the following,
`extraction of the features of the object under scrutiny at high
`the operation of the working example in FIG. 1 is described with
`speed. Furthermore, as recited in claim 3, in an image sensor
`reference to FIG. 2 to FIG. 4. First, the distance and direction of
`that enlarges/reduces/direction-converts a specified object in
`an object 65 that is present in front of the vehicle is measured
`an image, an optimum image for image processing can be
`by a distance measurement means 60 (not shown in FIG. 2)
`obtained, so that it is possible to obtain, from the image
`that is provided at the front end of one’s own vehicle 64. If (cid:84)x is
`processing means, detailed information that cannot be obtained
`set to the vehicle’s horizontal direction and (cid:84)y to the vertical
`from data with fewer pixels, such as information by which one
`direction (see FIG. 2), with this distance measurement means
`can recognize the license plate on a vehicle. Furthermore, in an
`60, data showing the distance to each bearing can be obtained
`invention, such as that recited in claim 4, which comprises a
`in a matrix L((cid:84)x,(cid:84)y). An example of the distance measurement
`measurement means that detects the travel state of one’s own
`results shown in FIG. 3 are the results of the case in which
`vehicle, and wherein the assessment means decides upon the
`there is an object 65 to the right [sic] as shown in FIG. 2. The
`object on which to perform image processing according to the
`assessment means 61 infers the position of the object based on
`detection results, if multiple objects are present in front of the
`the above measurement results. This inference method is
`vehicle, the object to scrutinize can be selected according to
`carried out for example as follows. Namely, for each L((cid:84)x,(cid:84)y),
`the one’s own vehicle’s travel state or the like. Furthermore, in
`the value
`is compared with a neighboring
` L((cid:84)x’,(cid:84)y’).
`the invention recited in claim 5, the configuration is such that
`Furthermore, because the values of L((cid:84)x,(cid:84)y) and L((cid:84)x’,(cid:84)y’) vary
`the distance and direction to a reflecting body are detected by a
`greatly at the border regions between where the object is
`reflecting body detection means; an image processing region
`present and where the object is not present, it is clear that the
`setting means is provided that sets the processing region in the
`object is present at that position. In the above example, the
`image processing recognition means according to the results;
`object is inferred to be to the right. In addition, the assessment
`and the image processing region is determined according to the
`means 61 sets the method of image processing based on the
`distance and direction to the reflecting body. Thus it becomes
`above results. In the case of this working example, processing
`possible to reliably detect the position of the preceding vehicle,
`to decide upon the region on which to perform image
`and to restrict the region on which to perform image processing
`processing is used as the method of image processing.
`to a narrow range, and thus it becomes possible to perform
`Therefore the assessment means 61 decides that the region on
`real-time
`computation
`processing without
`using
`an
`which to perform image processing is that surrounding the
`ultra-high-speed computer.
`location of the object. In the decision method at this time, the
`[0007]
`region is made larger than the object by multiplying the inferred
`[Working Examples]
`is
`invention
`this
`following,
`the
`In
`size of the object by a certain suitable value. Next, with respect
`described with reference to the drawings. FIG. 1 is a block
`to image information about the front of the vehicle determined
`diagram showing a first working example of this invention. In
`by the image sensor 62, based on information sent from the
`FIG. 1, a distance measurement means 60, which is for
`assessment means 61, the image processing means 63 sets
`example radar that uses light, radio waves, ultrasound waves,
`the region on which to perform image processing, and performs
`or the like, can obtain information on the distance and direction
`data processing focusing on that region. In the above example,
`to an object. Among [devices] that use light, there are those that
`image processing focuses on objects to the right. As above, as
`measure the distance by combining a laser with a photosensor
`a result of detecting the distance and direction of objects that
`and measuring the elapsed time for the laser light to be
`will block the travel of one’s own vehicle, and the assessment
`Translation by Patent Translations Inc. 1-800-844-0494 mail@PatentTranslations.com
`
`3
`
`

`
`(4)
`
`JP-06-124340-A
`
`
`
`means 61 performing processing focusing on extracting image
`interface 73, which is a device that exchanges information
`information targeting that object, the range in which data
`between the image processing device and an occupant, is for
`processing is performed by the image processing means 63 is
`example an operation switch and a display device provided
`restricted, so the number of data items to be handled is greatly
`inside the cab of the vehicle. An occupant operates this
`reduced, the processing step is speeded up, and extraction of
`operation switch to input signals to the image processing device,
`the features of the object under scrutiny can be realized at high
`and the information of the image processing device is given to
`speed.
`the occupant by being displayed on a display device.
`[0009] Next, FIG. 5 is a block diagram showing the second
`Furthermore, an image sensor 74 is the same as that used in
`working example of the present invention. In this working
`the second working example above. Furthermore, an
`example, the present invention is applied to an image
`assessment standard setting means 75 is a means (described
`processing device in which detailed image information is
`in detail below) that sets the assessment standard for an
`required for the object. In FIG. 5, the distance measurement
`assessment means 76. Furthermore, 76 is the assessment
`means 66 is the same as in FIG. 1 above. Furthermore, the
`means, and 77
`is an
`image processing means. The
`assessment means 67 infers the distance and direction to an
`assessment standard setting means 75, the assessment
`object in the same way as in FIG. 1, but in addition it outputs a
`means 76 and the image processing means 77 can be
`signal that controls the image sensor 68. Furthermore, the
`constituted by, for example, a computer. Note that S1 is a
`image sensor 68 is an image sensor that can enlarge, reduce,
`distance and direction signal, S2 is an image signal, S3 is an
`focus on, and rotation-control the image information according
`assessment signal, S4 is a feature extraction signal, and S5 is
`to control signals given from the assessment means 67 above.
`an enlargement/reduction/direction conversion signal, S6 is a
`For such an image sensor, one can use a video camera device
`vehicle speed signal, S7 is a steering angle signal, S8 is a
`standard value setting signal, and S9 is a standard signal.
`that has a lens that has a zoom mechanism, and a mechanism
`[0011] Next, the operation is described. If there are multiple
`that can rotate the camera as a whole. Furthermore, the image
`processing means 69 is, for example, a detailed image
`objects present in front of the vehicle, it becomes necessary to
`processing means that can recognize a vehicle license plate.
`set multiple image processing regions, but in this working
`Note that S1 is a distance and direction signal, S2 is an image
`example, the configuration is such that in a case such as this,
`signal, S3 is an assessment signal, S4 is a feature extraction
`the object that is to be scrutinized varies depending on the size
`signal, and S5 is an enlargement/reduction/direction conversion
`of, and distance to, the object, as well as the travel state of
`signal. In the environment shown in FIG. 2 above, an object is
`one’s own vehicle and the like. The assessment standard
`present to the right. With the distance measurement means 66,
`setting means 75 sets the assessment standard for the
`distance data is obtained in a matrix in the same way as in FIG.
`assessment means 76. That is to say, the assessment means
`1 above. Based on the above results, the assessment means
`76 assesses what kind of environment one’s own vehicle is
`67 infers the distance and direction to the object in the same
`currently in, and in accordance with this, the object to be
`way as in the first working example above, and controls the pan,
`scrutinized is decided upon, but in the above assessment, the
`tilt, zoom, and focus adjustment mechanism of the image
`assessment standard setting means 75 sets the assessment
`sensor 68. For example, if the data shown in FIG. 3 above is
`standard. For example, detection of the state of one’s own
`obtained, the camera is moved to the right side, and the focus
`vehicle is performed by detecting the travel speed and steering
`is adjusted to match the distance. With such processing, the
`angle by way of a vehicle speed sensor and a steering angle
`optimum image for image processing can be obtained.
`sensor, and if the travel speed is greater than or equal to a
`Therefore, detailed information that cannot be obtained from
`prescribed value and the steering angle is less than or equal to
`data with few pixels, such as information by which a vehicle’s
`a prescribed value, it can be assessed that it is traveling along
`license plate can be recognized, can be obtained from the
`a highway, while if the steering angle is greater than or equal to
`image processing means 69. Note detailed information that can
`a prescribed value and the vehicle speed is less than or equal
`be obtained with the above image processing means 69
`to a prescribed value, it can be assessed that it is traveling near
`includes the brake lamps of the preceding vehicle, the lighting
`an intersection, but the assessment standard setting means 75
`of its turn signals, the size of the vehicle, its direction of travel,
`sets the threshold values for the vehicle speed values and
`and the like, and the features of these can be extracted.
`steering angle values that will be the standard for this
`Furthermore, as a result of the image processing means 69
`assessment. The settings for these standard values are input
`performing image processing for the object of scrutiny that is
`using a human interface 73 such as operation switches. As
`set by the assessment means 67, features of pedestrians or
`stated above, the assessment means 76 assesses obstacles in
`buildings can also be extracted, and one can also recognize the
`front as the objects that are to be scrutinized if it assesses that
`situation in terms of traffic signs, the position of traffic signals,
`it is traveling along a highway, and assesses the traffic signal in
`the presence of any railroad crossings, road equipment and the
`front as the object that is to scrutinized if it assesses that it is
`like.
`traveling near an intersection. Furthermore, image processing
`[0010] Next, FIG. 6 is a block diagram of a third working
`is performed by the image processing means 77 on the object
`example of the present invention. In FIG. 6, a distance
`that is to be scrutinized. Note that, in the above description, a
`measurement means 70 is the same as that used in the first
`case in which the setting of the standard values of the
`working example. Furthermore, a vehicle speed sensor 71
`assessment standard setting means 73 is performed using a
`measures the travel speed of the vehicle; for example, it
`human interface 73 is described, but one can also perform the
`detects the rotation speed of a wheel per unit time, and
`environment setting automatically, by way of inputting the
`calculates the speed of the vehicle from the length of the
`image processing results. For example, if the present invention
`circumference of the wheel, or it reflects light or radio waves
`is applied to a system in which the image processing means 77
`onto the road surface and calculates the speed by way of the
`detects white lines on the road, then using the property that a
`Doppler effect. Furthermore, a steering angle sensor 72 detects
`continuous white line will not be detected near an intersection, if
`the steering angle; for example, it makes use of a steering
`an absence of the white line is detected, the assessment will be
`wheel that has a built-in rotary encoder. Furthermore, a human
`that it is near an intersection, and the object that is to be
`Translation by Patent Translations Inc. 1-800-844-0494 mail@PatentTranslations.com
`
`4
`
`

`
`(5)
`
`JP-06-124340-A
`
`
`
`scrutinized can be set to be the traffic signal in front.
`Summarizing the above, we have the following. First, the
`distance and direction to an object is measured by the distance
`measurement means 70. Depending on these measurement
`results and the travel situation of the vehicle, the assessment
`standard setting means 75 and the assessment means 76
`decide upon the object on which to perform image processing.
`For example, if it is assessed as traveling on a highway, the
`preceding vehicle is taken as the object, and if it is assessed as
`traveling near an intersection, the traffic signal is determined to
`be the object. But setting can be made as appropriate
`depending on the situation, so this is not limited to the above
`example. Furthermore, when performing image processing, the
`assessment means
`76 makes
`an
`adjustment
`(enlargement/reduction/direction conversion, or the like) to the
`image sensor 74 so as to result in the optimum image, and
`decides which part of the image taken in from the image sensor
`74 is to be processed. The image processing means 77, which
`has taken in the image of the image sensor 74, performs
`feature extraction of the object in accordance with the targeted
`object. This feature extraction may be, for example, detection of
`an obstacle, detection of the lighting up of brake lamps on a
`vehicle for which there is risk of a collision, recognition of
`restricted speed as indicated on a traffic sign, or the like. In
`addition, by calculating the temporal change in the distance
`information, the relative speed between one’s own vehicle and
`the targeted object can also be detected. Note that, as in the
`second working example, in this working example as well,
`detailed information obtained by the image processing means
`77 includes the brake lamps of the preceding vehicle, the
`lighting-up of turn signals, the size of a vehicle, the direction of
`travel, and the like, and these features can be extracted.
`Furthermore, with regard to the object of scrutiny that is set by
`the assessment means 76, as a result of the image processing
`means 77 performing image processing, the features of
`pedestrians or buildings can be extracted, and one can
`recognize the situation, including traffic signs, the positions of
`traffic signals, the presence any railroad crossings, road
`equipment and the like. Furthermore, additional distance
`measurement means 70 or image sensors 74 can be installed
`as necessary, such as on the front, rear, left, or right of the
`vehicle. In this case, the features of an object can be extracted
`in independent directions.
`[0012] Next, a working example in which the present invention
`is applied to the detection of the preceding vehicle is described.
`In terms of conventional preceding vehicle detection devices,
`there are
`those
`that make use of
`the
`reflection of
`electromagnetic waves, as described
`for example
`in
`JP-61-023985-A and the like. This is such that, by emitting
`electromagnetic waves (for example, laser light or the like)
`while sweeping through a prescribed angle, receiving the wave
`reflected from a reflecting body, and calculating the distance to
`the reflecting body based on the propagation delay time from
`the emission to the reception of the electromagnetic wave at
`prescribed sweep angles, the distance and direction from one’s
`own vehicle to the reflecting body is detected, and information
`on the direction and distance from one’s own vehicle to a
`reflecting object can be obtained. Note that, in general, reflex
`reflectors are installed at the rear of a vehicle in order to
`improve its visibility from behind, and this reflex reflector, being
`a reflecting body, reflects laser light and other electromagnetic
`waves, making easy detection possible. Furthermore,
`in
`addition to this, a device has also been devised in which, using
`a television camera or the like, which is oriented to the front of
`
`
`the vehicle, the scenery in front of the vehicle is input, image
`Translation by Patent Translations Inc. 1-800-844-0494 mail@PatentTranslations.com
`
`processing is performed on the image that is input, and the
`preceding vehicle or road is recognized.
`[0013] However, a conventional preceding vehicle detection
`device such as this has presented the following problems. First,
`in a preceding vehicle detection device that makes use of the
`reflection of an electromagnetic wave such as laser radar, it is
`possible that there will be, not only reflex reflectors provided on
`the rear of the vehicle as reflecting bodies, but also corner
`reflectors and the like on a guard rail installed on the shoulder
`of the road, and thus there is the problem that it is very difficult
`to select only the reflection from the reflex reflectors on the
`preceding car from among a large number of reflecting bodies.
`Furthermore, it is relatively easily possible to compare the
`amount of change per unit time in the detected distance to the
`reflecting body with one’s own vehicle travel speed, and to
`distinguish whether the reflecting body is a stationary object or
`a moving object, and to recognize only moving objects as
`vehicles. But with this method there is the problem that, for a
`vehicle or like that is stopped at the tail end of congestion on a
`highway, an assessment will be made to the effect that,
`because it is a stationary object, it is not a vehicle, and thus the
`position of the preceding vehicle cannot be detected, and
`because of this, it is impossible to perform high-precision travel
`control or to give suitable warning for approaching another
`vehicle too closely. Furthermore, in a preceding vehicle
`detection device that image-processes the image from a
`television camera and recognizes the preceding vehicle, with
`the current technology, it is relatively easily possible to use
`image processing to recognize the white lines that indicate the
`edge of the roadway or traffic lanes, but one cannot expect very
`high precision
`for distinguishing a preceding vehicle.
`Furthermore, for distinguishing a preceding vehicle, it is also
`necessary to perform processing many times, which makes it
`necessary to process a large volume of image information.
`Then there is the problem that, if this is applied to vehicle
`automatic travel or warning devices for a rear-end collisions or
`the like, it is essential that such processing be performed at
`high speed (in real time), which requires a very-high-speed
`computer. Furthermore, in technology that uses ordinary image
`processing for purposes other than preceding vehicle detection,
`the region within the entire screen on which image processing
`must be performed (the region under scrutiny) is limited, and
`various types of processing will be performed within this
`[region]; thus, a method can be applied that reduces the overall
`calculation volume, but if a preceding