JP2000163696A - Picture recognizing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recognize the registered number of a traveling object in a short processing time. SOLUTION: During one time of photographing operation of an image picking-up means 11, a control means 15 controls the turning-on/off time of an illuminating means 12. The image picking-up means 11 takes the picture of an ordinary type registered number 2 or a light emitting type registered number 2 and stores the signal quantity corresponding to the characters of the registered number 2 and background in a charge storing means incorporated in the means 11 during one time of photographing operation. A character recognizing means 13 recognizes the characters of the registered number 2 based on the signal quantity stored in the charge storing means incorporated in the image picking-up means 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image capturing system for a moving object such as an automobile, a train, an aircraft, a ship, and the like, for the management of a traffic system and the like. The present invention relates to an image recognition device for automatically recognizing characters and symbols indicating names, destinations, and the like.

[0002]

2. Description of the Related Art FIG. 5 is a diagram showing a configuration of a conventional image recognition apparatus for automatically recognizing a registration number of a vehicle and managing a passing state of a vehicle and a vehicle allocation management. In FIG. 5, 1
Is a car as a subject approaching the image recognition device,
Reference numeral 2 denotes a registration number as a part to be recognized attached to the subject 1. Reference numeral 11 denotes, for example, a CCD installed toward the automobile 1.
An imaging unit such as a camera, 12 is an illuminating unit that illuminates the field of view of the imaging unit 11, and 13 is a registration number 2 detected from an output image of the imaging unit 11 and is detected by image processing or the like. And character recognition means for automatically recognizing characters and symbols.

Next, the operation will be described. When the car 1 passes through the field of view of the imaging means 11, the car 1 is imaged by the imaging means 11 and an image thereof is obtained. FIG. 6 is a diagram showing an example of the registration number 2, in which 21 is a background portion painted with white paint, and 22 is a character portion painted with green paint. FIG. 7 is a cross-sectional view taken along the line AA ′ of FIG.

The registration number 2 of the car 1 is, for example, as shown in FIG. 6, when the car 1 is a passenger car, the character portion is green and the background portion is white, and as shown in FIG. Since the reflectance differs between the light and the background portion 21, reflected light having different intensities is generated with respect to uniform incident light. Therefore, even in an image captured by the imaging unit 11, the signal amounts of the two are different, and generally, the reflectance corresponding to the white color is high and the signal amount is large. Based on this difference in signal amount, the character recognizing means 13 automatically recognizes the content of the registration number 2 by using a binarization process, a pattern matching process, or the like.

However, since the surroundings are dark at night when there is no sunlight, the imaging means 11 cannot capture the registration number 2 of the car 1 with a sufficient signal amount, and the character recognition means 13 cannot recognize the registration number 2. It will be difficult. for that reason,
By illuminating the field of view of the imaging unit 11 with the illumination unit 12, a sufficient signal amount is obtained even at night so that stable recognition can be performed.

Here, the brightness of the illuminating means 12 is set so that the signal amount at night is almost equal to the signal amount at daytime without illumination. In addition, in order to obtain a stable image without being affected by the weather or the like and to prevent the driver from feeling dazzling in the field of road traffic, illumination light in the near infrared region is often used for the illumination means 12.

[0007] By the way, the registration number 2 attached to the automobile 1 has a character portion itself illuminated in addition to the one coated on a normal metal plate as shown in FIG. 7 (hereinafter referred to as a normal registration number). (Hereinafter referred to as a self-lighting registration number). FIG. 8 is a diagram showing a cross section of the registration number 2 of the self-light type. 8, the same symbols or numerals as those in FIG. 7 denote the same parts, and a description thereof will be omitted. Reference numeral 23 denotes a character portion formed of a green transparent resin, and reference numeral 24 denotes a light source. As shown in the figure, the light arriving at the imaging means 11 from the character portion 23 includes:
In addition to the reflected light due to the illumination light, there is emitted light of near-infrared light from the light emitting source 24.

In the image recognition apparatus shown in FIG. 5, when the self-light registration number 2 is included in the field of view of the imaging means 11,
In addition to the reflected light by the illumination light from the illuminating means 12, the imaging means 11 also directly receives the near-infrared light emitted from the character part 23, and the signal amount sufficient for the background part 21 and the character part 23. (Hereinafter referred to as contrast), and the self-light registration number 2 is not
Makes stable recognition difficult.

FIG. 9 is a diagram for explaining the output of the image pickup means 11 and the recognition processing by the character recognition means 13, and shows a case where a normal registration number 2 and a self-lighting registration number 2 are imaged at night. When the illumination by the illuminating means 12 is turned off and the normal registration number 2 is imaged, as shown in FIG.
In both cases, a sufficient signal amount cannot be obtained, and the character portion 22 and the background portion 21 cannot be distinguished from each other.

Further, when the illumination by the illumination means 12 is turned on and the normal registration number 2 is imaged, the imaging means 1
From 1, an output corresponding to the intensity of the illumination light and the magnitude of the reflectance is obtained. In general, even in the near-infrared light, the reflectance in the white background portion 21 is higher and the output is larger, and as shown in FIG.
An output difference corresponding to the difference in the reflectance is obtained between the character portion 22 and the background portion 21. The character portion 22 is distinguished from the background portion 21 by dividing the two by an appropriate predetermined threshold value in the character recognition means 13. Can be recognized.

Further, when the illumination by the illuminating means 12 is turned off and the self-registration type registration number 2 is imaged, FIG.
As shown in FIG. 9C, the output difference between the light emitting character portion 23 and the non-light emitting background portion 21 in the imaging means 11 increases, and the character By separating the two by the threshold value, the character portion 23 and the background portion 21 can be distinguished from each other, and recognition can be performed.

However, when the illumination by the illumination means 12 is turned on and the self-registration registration number 2 is imaged, FIG.
As shown in (D), in the imaging unit 11, both the character part 23 and the background part 21 exceed the threshold value, so that the difference between the two decreases and the recognition by the character recognition unit 13 becomes difficult.

An image recognizing apparatus has already been proposed which solves the problem that it is difficult to recognize the self-registration registration number 2 during illumination as described above. FIG. 10 is Japanese Patent Laid-Open No. 9-28.
FIG. 1 is a diagram showing a conventional image recognition device disclosed in Japanese Patent Application Laid-Open No. 2447 and Japanese Patent Application Laid-Open No. Hei 7-121794, and corresponding parts are denoted by the same reference numerals as in FIG. 5 and description thereof is omitted. In FIG. 10, an illumination control unit 14 controls the illumination unit 12 in accordance with the shutter of the imaging unit 11.

Next, the operation of the image recognition apparatus shown in FIG. 10 will be described. In this image recognition apparatus, under the control of the illumination control unit 14, the illumination unit 12 repeats blinking in accordance with the shutter of the imaging unit 11, and the imaging unit 11 outputs an image with illumination by the illumination unit 12 and an image without illumination. And are obtained alternately. The character recognizing unit 13 performs recognition processing on two images of the same automobile 1 with and without illumination captured by the image capturing unit 11, and adopts a higher recognition degree. That is, in the case of the normal registration number 2, FIG.
As shown in FIG. 9B, a recognition result based on an image with illumination is adopted. In the case of the self-lighting registration number 2, a recognition result based on an image without illumination is adopted as shown in FIG.

As described above, the conventional image recognition apparatus recognizes the registration number 2 of the automobile 1 irrespective of whether it is the normal registration number 2 or the self-lighting registration number 2. .

[0016]

Since the conventional image recognition apparatus is configured as described above, it is necessary to capture and acquire two types of images with and without illumination for the same automobile 1. For this reason, there is a problem that the processing time for recognition of one car 1 is long.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and it is not necessary to take an image with illumination and an image without illumination, and image recognition can be performed in a short processing time. The aim is to obtain a device.

[0018]

SUMMARY OF THE INVENTION An image recognition apparatus according to the present invention captures an image of an object to be recognized consisting of a character portion and a background portion attached to a moving body such as a vehicle, and corresponds to the character portion and the background portion. Imaging means for outputting a signal amount to be illuminated, illumination means for illuminating the visual field of the imaging means, and control of the lighting time and extinction time of the illumination light by the illumination means within the imaging time of the recognition target by the imaging means. And a character recognition means for recognizing the character part in the recognized part based on a signal amount corresponding to the character part and the background part output from the imaging means and a predetermined threshold value. It is provided.

In the image recognition apparatus according to the present invention, the control means can recognize the character portion in the normal recognition target portion that does not use radiation light (not the self-lighting type) by the character recognition means so that the character portion can be recognized. The lighting time of the illuminating means and the extinction time of the illuminating means are controlled so that the lighting time of the light is controlled and the character part in the (self-lighting) recognized part using the emitted light can be recognized by the character recognizing means. Is what you do.

An image recognition apparatus according to the present invention captures an image of an object to be recognized, which includes a character portion and a background portion attached to a moving body such as a vehicle, and outputs a signal amount corresponding to the character portion and the background portion. An imaging unit, an illumination unit that illuminates a field of view of the imaging unit, a control unit that controls the intensity of illumination light by the illumination unit within an imaging time of the recognition target unit by the imaging unit, and And character recognition means for recognizing the character portion in the recognized portion based on the output signal amounts corresponding to the character portion and the background portion, and a predetermined threshold value.

In the image recognition device according to the present invention, the control means uses the character recognition means to use the character portion in the normal recognized portion which does not use the emitted light (not the self-lighting type) and the emitted light. The intensity of the illuminating light by the illuminating means is controlled so that the character portion in the recognized portion (of the formula) can be recognized.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a diagram showing a configuration of the image recognition device according to the first embodiment. In the figure, the same symbols or numerals as in FIG. 5 indicate the same parts. 15 is lighting of the lighting means 12,
This is a control unit that integrally controls turning off and start and end of imaging by the imaging unit 11. Although not shown in the figure, the imaging unit 11 includes a shutter for controlling the start and end of the imaging.

Next, the operation will be described. FIG. 2 is a timing chart showing the operation timing of the shutter and the illumination unit 12 of the imaging unit 11 and the change of the signal amount stored in the charge storage unit (not shown) in the imaging unit 11. At time T1, the control unit 15
At the same time as starting the imaging by opening the shutter 1, the illuminating means 12 is switched from the unlit state to the lit state.

At time t from time T1 to time T2, the control means 15 keeps the lighting state of the lighting means 12. When a CCD camera or the like is used as the imaging means 11, the character part 22 and the background part 21 of the normal registration number stored in the charge storage means in the imaging means 11 and the character part 23 and the background part 21 of the self-registration registration number From time T1 to T
At a time t of 2, the value increases in proportion to the product of the light receiving intensity of the imaging means 11 and the light receiving time. As shown in FIG. 2, depending on the difference in reflectance and the presence or absence of emitted light, the increasing gradient is based on the character part 22 of the normal registration number, the character part 23 of the self-registration registration number, and the background part 21. Different.

At time T2 when the time t at which the contrast between the background portion 21 and the character portion 22 in the normal registration number 2 becomes a value sufficient for character recognition in the character recognition means 13 has passed, the control means Reference numeral 15 changes the lighting unit 12 from the lit state to the unlit state.

At time T2, the contrast between the background portion 21 and the character portion 23 of the self-lighting registration number 2 is not sufficient for the above-described reason. After the time T2, the signal amount from the character part 23 of the self-light registration number becomes
The light portion 22 and the background portion 21 of the normal registration number and the background portion 21 of the self-registration type registration number continue to rise by the emitted light at a gentle gradient only by the gradient reduced by the light reflected by the illumination means 12, The signal amount stored until time T2 is maintained.

At time T3 when the time Δt at which the contrast between the background portion 21 and the character portion 23 in the self-lighting registration number 2 becomes a value sufficient for character recognition in the character recognition means 13 has elapsed. The control unit 15 causes the shutter of the imaging unit 11 to close. That is, Δt
Can be adjusted independently of the normal registration number 2 contrast. The imaging unit 11 outputs the signal amount stored in the charge storage unit to the character recognition unit 13 after the elapse of the time T3.

FIG. 3 is a diagram for explaining the output of the image pickup means 11 and the recognition processing by the character recognition means 13. As shown in FIG. 3A, the output of the character portion 22 and the background portion 21 in the normal registration number 2 can be distinguished by the predetermined threshold value 1. 2 can be recognized. Also, as shown in FIG. 3B, the output of the character portion 23 and the background portion 21 in the self-lighting registration number 2 can be distinguished by a predetermined threshold value 2. The self-light registration number 2 can be recognized by the means 13.

As described above, the character recognizing means 13 performs two recognizing processes on one image obtained by one image capturing process at different threshold values (threshold value 1 and threshold value 2). By adopting the higher one, the registration number 2 can be recognized in a short processing time regardless of whether it is the self-lighting type or not. Here, the threshold value 1 is determined based on the intensity of the illumination light, the magnitude of the reflectance, and the time t in FIG.
The threshold value 2 is determined based on the intensity of the illumination light and the emitted light, the magnitude of the reflectance, and the time t and the time Δt in FIG.

Here, for example, a case is considered in which the registration numbers of all vehicles passing continuously on a general road with a good flow are to be recognized without omission. Assuming that the minimum inter-vehicle distance of the automobile 1 is 5 m and the maximum speed is 100 km, it is necessary to perform imaging and processing at a cycle of at least 180 msec or less. The processing time of the character recognition means 13 needs to be shorter than the processing cycle. However, considering the scale of the processing, the shorter the processing time, the larger the scale of the character recognition means 13.

As described above, in the conventional image recognition apparatus shown in FIG. 10, it is necessary to perform the image pickup process twice for the automobile 1, but in this embodiment, the recognition is performed by one image pickup process. Reduces the processing time.

As described above, according to the first embodiment, the control unit 15 controls the lighting time and the light-off time of the illumination means 12 during one imaging time of the imaging means 11, so that The output difference between the output of the character part and the output of the background part in the registration number 2 of the self-registration type, and the output difference between the output of the character part and the output of the background part in the self-lighting registration number 2 can be caused. Therefore, there is an effect that recognition can be performed in a short processing time.

Embodiment 2 FIG. The configuration of the image recognition apparatus according to this embodiment is the same as that of the first embodiment shown in FIG.

Next, the operation will be described. FIG. 4 shows a shutter and an illumination unit 1 of an imaging unit 11 according to the second embodiment.
6 is a timing chart showing the operation timing of No. 2 and a change in the signal amount stored in a charge storage unit (not shown) in the imaging unit 11. Exposure time of the imaging means 11 (t + Δ
t) is set in the same manner as in FIG. 2 in the first embodiment.
The illumination of the illumination unit 12 is turned on and off at the same timing as the opening and closing of the shutter of the imaging unit 11.

As described above, the signal amount of the image picked up by the image pickup means 11 is proportional to the product of the light receiving intensity of the image pickup means 11 and the light receiving time. Therefore, the intensity P1 of the illumination light in the first embodiment and the intensity P2 of the illumination light in the second embodiment
P2 is set so that the relationship with the following equation (1). P2 (t + Δt) = P1 · t (1)

The change in the signal amount when illuminated with the illumination light intensity P2 obtained by the above equation (1) increases as shown in FIG. 4 with a gentler gradient than in FIG. Even so, the control means 15 does not turn off the lighting means 12,
At the time T3, at time T3, the character portion 22 and the background portion 21 in the normal registration number 2 and the character portion 23 and the background portion 21 in the self-lighting registration number 2 result in the same as FIG. The output difference is obtained. The imaging unit 11 outputs the signal amount stored in the charge storage unit to the character recognition unit 13 after the elapse of the time T3.

Illumination light intensity P2 in the second embodiment
Is obtained by the above equation (1).
As shown in FIG. 3A, the output of the character portion 22 and the background portion 21 of the normal registration number 2 in the second embodiment is also distinguished by the predetermined threshold value 1 used in the first embodiment. Therefore, the normal registration number 2 can be recognized by the character recognition means 13.

As shown in FIG. 3B, the output of the character portion 23 and the background portion 21 of the self-lighting registration number 2 in the second embodiment is also performed by the predetermined threshold used in the first embodiment. Since the distinction can be made with the value 2, the self-lighting type registration number 2 can also be recognized by the character recognizing means 13.

As described above, the character recognizing means 13 performs two recognizing processes on one image obtained by one image capturing process at different threshold values (threshold value 1 and threshold value 2). By adopting the higher one, the registration number 2 can be recognized in a short processing time regardless of whether it is the self-lighting type or not. Here, the threshold 1 in this embodiment is determined based on the intensity of the illumination light, the magnitude of the reflectance, and the time (t + Δt) in FIG. 4, and the threshold 2 is determined based on the illumination light and the emission light. It is determined based on the intensity, the magnitude of the reflectance, and the time (t + Δt) in FIG.

As described above, according to the second embodiment, the control unit 15 controls the intensity of the illuminating light while the illuminating unit 12 is turned on during one imaging time of the imaging unit 11. By doing so, it is possible to cause an output difference between the output of the character portion and the output of the background portion in the normal registration number 2, and the output of the character portion and the output of the background portion in the self-lighting registration number 2 Since an output difference can be generated, an effect that recognition can be performed in a short processing time is obtained.

Further, as compared with the first embodiment, the illumination means 1
Since the intensity of the illumination light can be reduced, the load on the illumination means 12 can be reduced, and for example, a type of illumination means 12 that obtains a desired amount of light by arranging a number of light sources such as light bulbs.
In this case, the number of light sources can be reduced and the size of the device can be reduced.

[0042]

As described above, according to the present invention, the image pickup means picks up an image of the part to be recognized consisting of the character portion and the background portion, and outputs a signal amount corresponding to the character portion and the background portion.
The effect that the character recognition means can recognize the character portion in the recognition target part by controlling the lighting time and the light-off time of the illumination light by the illumination means within the imaging time of the recognition target part by the imaging means. There is.

According to the present invention, the image pickup means picks up an image of the part to be recognized consisting of the character part and the background part, outputs a signal amount corresponding to the character part and the background part, and sets the image pickup time of the part to be recognized by the image pickup means. The control unit controls the intensity of the illumination light by the illumination unit, whereby the character recognition unit can recognize the character portion in the recognition target portion.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an image recognition device according to a first embodiment of the present invention.

FIG. 2 is a timing chart showing operation timings of a shutter and an illuminating unit of the imaging unit and a change in a signal amount stored in a charge storage unit in the imaging unit according to the first embodiment of the present invention;

FIG. 3 is a diagram illustrating an output of an image pickup unit and a recognition process by a character recognition unit according to the first embodiment of the present invention;

FIG. 4 is a timing chart showing operation timings of a shutter and an illuminating unit of an imaging unit and a change in a signal amount stored in a charge storage unit in the imaging unit according to a second embodiment of the present invention;

FIG. 5 is a diagram illustrating a configuration of a conventional image recognition device.

FIG. 6 is a diagram showing an example of a normal registration number.

FIG. 7 is a diagram showing a cross section of a normal registration number.

FIG. 8 is a diagram showing a cross section of a self-optical registration number.

FIG. 9 is a diagram illustrating a conventional output of an imaging unit and a recognition process performed by a character recognition unit.

FIG. 10 is a diagram showing a configuration of a conventional image recognition device.

[Explanation of symbols]

11 imaging means, 12 lighting means, 13 character recognition means, 15 control means.

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 5B029 AA01 AA05 BB02 CC03 CC21 CC28 5B057 AA06 BA02 BA19 DA20 DB02 DC22 5H180 AA01 AA25 AA26 AA27 CC04 CC24 DD01

Claims (4)

[Claims] 1. An image pickup means for picking up an image of a part to be recognized comprising a character portion and a background portion attached to a moving body such as a vehicle, and outputting a signal amount corresponding to the character portion and the background portion; Lighting means for illuminating the field of view; control means for controlling the lighting time and extinction time of the illumination light by the lighting means within the imaging time of the part to be recognized by the imaging means; and An image recognition apparatus comprising: character recognition means for recognizing the character portion in the recognized portion based on a signal amount corresponding to the character portion and the background portion, and a predetermined threshold. 2. The control means controls the lighting time of the illuminating light by the illuminating means so that the character recognizing means can recognize the character portion in the normal recognition target part which does not use the radiated light. 2. The image recognition device according to claim 1, wherein a lighting time and a lighting time of the illumination light by the illumination unit are controlled so that a character portion in the recognition target portion using light can be recognized. 3. An image pickup means for picking up an image of a part to be recognized consisting of a character portion and a background portion attached to a moving body such as a vehicle, and outputting a signal amount corresponding to the character portion and the background portion; Illumination means for illuminating the field of view; control means for controlling the intensity of illumination light by the illumination means within the imaging time of the recognized part by the imaging means; and the character portion output from the imaging means; An image recognition apparatus comprising: character recognition means for recognizing the character portion in the recognized portion based on a signal amount corresponding to the background portion and a predetermined threshold. 4. The lighting device according to claim 1, wherein the controller recognizes the character portion in the normal recognition target portion using no radiation light and the character portion in the recognition target portion using the radiation light by the character recognition device. The image recognition device according to claim 1, wherein the intensity of the illumination light is controlled.