JP6424449B2 - Rear status display device, rear status display method - Google Patents

Description

  The present invention relates to a technology for displaying on a display screen an image obtained by capturing a situation behind a vehicle using a vehicle-mounted camera.

  It is necessary for the driver of the vehicle to drive while confirming not only the traveling direction of the vehicle but also the situation in the direction opposite to the traveling direction (hereinafter, "rearward") and the situation behind the vehicle side. For this reason, in a general vehicle, a rearview mirror for checking the rear of the vehicle and a side mirror or a door mirror (hereinafter, side mirror etc.) for checking the rear of the side portion are mounted.

  However, in order to confirm the rear with a side mirror or the like, it is necessary to project the side mirror or the like from the side of the vehicle. For this reason, the side mirror or the like becomes air resistance to lower the motion performance and the fuel consumption performance of the vehicle, or when raindrops, raindrops adhere to the mirror surface, making it difficult to check the rear. Furthermore, if the side mirror or the like is enlarged in an attempt to widen the confirmation range, the air resistance increases, so there is also a problem that it is difficult to secure a sufficient confirmation range.

  Therefore, instead of a side mirror or the like, an electronic camera incorporating an imaging device (CCD, CMOS, etc.) is attached to the side of the vehicle, and an image of the rear taken from the side of the vehicle with the electronic camera is A technique (so-called electronic mirror system) for confirmation has been proposed (Patent Document 1). Since the electronic camera is smaller than the side mirror or the like, it is possible to suppress an increase in air resistance due to being provided on the side of the vehicle. In addition, if a small recess is formed on the surface of the vehicle and the electronic camera is mounted on the recess, raindrops can be prevented from adhering to the surface when it is raining and the visibility can be prevented. Furthermore, if a wide-angle lens is used in combination, it is also possible to secure a sufficient confirmation range.

JP, 2012-138828, A

However, the electronic mirror system described above has a problem that it is difficult for the driver to check the situation behind the side of the vehicle under the situation where there is a vehicle following from behind the vehicle at night. there were. This is due to the following reasons. First, at night, the headlights of the following vehicles are turned on. Then, since the electronic camera shoots the following vehicle from the front, the headlight is shot from the front. As a result, in the obtained photographed image, a large area around the headlight becomes a white image, and not only the situation corresponding to that area can not be confirmed, but also the white area is It is because it becomes too bright and it becomes difficult to understand the condition of the surrounding area.
In addition, the above-mentioned problem may occur not only in an electronic mirror system in which an electronic camera is mounted instead of a side mirror, but also in a system in which an electronic camera is mounted instead of a rearview mirror.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and aims to provide a technology that allows the driver to easily confirm the situation behind the vehicle at night.

In order to solve the problems described above, the rear situation display device and the rear situation display method according to the present invention detect the brightness of the location where the headlights of the following vehicles appear in the rear image, and the brightness exceeds a predetermined threshold. If this is the case, correction is performed to reduce the brightness in the area where the headlights appear. At this time, in the first area including the central portion of the headlight, the reduction rate of luminance is suppressed more than in the second area provided surrounding the first area.

In this way, even if the headlight of the following vehicle is dazzling in the rear image, the brightness is reduced (except for the central portion of the headlight) in the area where the headlight appears. Further, in the central portion of the headlight, the reduction rate of luminance is suppressed more than in the portions other than the central portion. For this reason, it is possible to avoid a situation in which it becomes difficult for the driver who confirms the rear image to be able to confirm the surrounding situation because the headlights of the following vehicles are dazzling. In addition, since the central portion of the headlight is brightly displayed, the driver who checks the rear image can easily grasp the position of the following vehicle from the position of the headlight.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which shows the vehicle 1 carrying the back condition display apparatus 100 of a present Example. FIG. 2 is an explanatory view showing a rough internal configuration of a rear situation display device 100. It is a flowchart of the back condition display process which the back condition display apparatus 100 performs. It is explanatory drawing which illustrated the standard mask applied in order to reduce the brightness | luminance of high-intensity area | regions other than the headlight of a following vehicle. It is a flowchart of a headlight mask process. It is explanatory drawing which illustrated the mask for headlamps applied in order to reduce the brightness | luminance of the headlamp of a following vehicle. It is explanatory drawing which showed a mode that the size of the mask for headlamps was determined according to the magnitude | size of the following vehicle. It is explanatory drawing which illustrated the back image at the time of applying the mask for headlights to the headlight of a following vehicle.

Below, in order to clarify the contents of the present invention mentioned above, an example is described.
A. Device configuration :
FIG. 1 shows a vehicle 1 on which a rear situation display device 100 is mounted. As illustrated, the vehicle 1 is mounted on the left side surface of the vehicle 1 and captures a left rear condition 10L, and a right rear camera mounted on the right surface of the vehicle 1 and capturing a right rear condition 10R, a left rear monitor 20L on which an image photographed by the left rear camera 10L is displayed, a right rear monitor 20R on which an image photographed by the right rear camera 10R is displayed, and a rear situation display device 100.

The left rear monitor 20L is provided in the vehicle compartment obliquely forward to the left as viewed from the driver, and the right rear monitor 20R is provided in the vehicle compartment obliquely forward to the right as viewed from the driver.
The rear situation display device 100 receives image data from the left rear camera 10L, performs predetermined image processing to be described later, and displays the image data on the left rear monitor 20L. Similarly, image data is received from the right rear camera 10R, subjected to predetermined image processing to be described later, and displayed on the right rear monitor 20R.
Furthermore, in the present embodiment, the rear camera 12 is mounted at the center of the rear of the vehicle 1, and a rear monitor 22 for displaying an image captured by the rear camera 12 is also mounted in the vehicle compartment ahead of the driver. ing.

  The left rear camera 10L, the right rear camera 10R, and the rear camera 12 correspond to the “vehicle-mounted camera” in the present invention, and the left rear monitor 20L, the right rear monitor 20R, and the rear monitor 22 according to the present embodiment , Corresponds to the "display screen" in the present invention.

In the vehicle 1 of this embodiment, the driver can easily grasp the rear situation of the vehicle 1 by confirming the left rear monitor 20L, the right rear monitor 20R, and the rear monitor 22.
However, since the left rear camera 10L, the right rear camera 10R, and the rear camera 12 shoot the following vehicle from the front, when the following vehicle lights the headlights at night, the light of the headlights is adjusted properly. Will be As a result, in the images displayed on the left rear monitor 20L, the right rear monitor 20R, and the rear monitor 22, the surroundings of the headlights of the following vehicles may be white in a wide range, and the driver may be behind the vehicle 1 It will be difficult to confirm. Furthermore, since the white parts are too bright, it is difficult to confirm the rear situation even in the surrounding area.
Therefore, in the rear situation display device 100 of the present embodiment, the images taken by the left rear camera 10L, the right rear camera 10R, and the rear camera 12 are displayed as they are on the left rear monitor 20L, the right rear monitor 20R, and the rear monitor 22. Instead, they are displayed after image processing to be described later.

The rough internal structure of the back condition display apparatus 100 of a present Example is shown by FIG. As illustrated, the rear situation display device 100 of the present embodiment includes a rear image acquisition unit 101, a following vehicle detection unit 102, an image correction unit 103, a storage unit 104, and an image display unit 105. .
Note that these five “parts” pay attention to the function of the rear situation display device 100 displaying the image of the rear of the vehicle 1 on the left rear monitor 20 L, the right rear monitor 20 R, and the rear monitor 22. Is an abstract concept in which the inside of the rear light indicator 100 is classified for convenience, and does not represent that the rear situation display device 100 is physically divided into five parts. Therefore, these "units" can be realized as computer programs executed by the CPU, or as electronic circuits including LSIs and memories, and further realized by combining them. You can also.

The rear image acquisition unit 101 is connected to the left rear camera 10L, the right rear camera 10R, and the rear camera 12, and an image of the left rear camera 10L, the right rear camera 10R, and the rear camera 12 capturing the rear of the vehicle 1 Is acquired at a fixed cycle (about 30 Hz). Then, the acquired photographed image is output to the following vehicle detection unit 102 and the image correction unit 103.
In the present embodiment, the rear image acquisition unit 10 corresponds to the “rear image acquisition means” in the present invention.

The subsequent vehicle detection unit 102 analyzes the captured image received from the rear image acquisition unit 101 to detect a subsequent vehicle present behind the vehicle 1. In the present embodiment, not only vehicles but also motorcycles, bicycles and the like are detected as following vehicles. When a plurality of following vehicles are shown, the plurality of following vehicles are detected. Then, the obtained detection result is output to the image correction unit 103. The detection of the following vehicle can use a known method of searching for an image portion having a feature of the vehicle using a method such as pattern matching.
In the present embodiment, the following vehicle detection unit 102 corresponds to the "following vehicle detection means" in the present invention.

The image correction unit 103 refers to the photographed image received from the rear image acquisition unit 101 and the detection result of the following vehicle received from the following vehicle detection unit 102 while referring to the storage unit 104 and using the following method Correct the Then, the corrected captured image is output to the image display unit 105.
In the present embodiment, the image correction unit 103 corresponds to the “image correction unit” in the present invention.

The image display unit 105 displays the image indicating the situation behind the vehicle 1 by outputting the image data thus received from the image correction unit 103 to the left rear monitor 20L, the right rear monitor 20R, and the rear monitor 22.
In the present embodiment, the image display unit 105 corresponds to the "image display means" in the present invention.

B. Rear status display process:
The flowchart of the back condition display process which the back condition display apparatus 100 mentioned above performs is shown by FIG.
In the rear situation display process (S100), first, a rear image is acquired (S101).
That is, an image obtained by capturing the rear from the left side of the vehicle 1 is acquired from the left rear camera 10L, and an image obtained by capturing the rear from the right side of the vehicle 1 is acquired from the right rear camera 10R. Furthermore, when the rear camera 12 is mounted, an image obtained by capturing the rear from the rear center of the vehicle 1 is acquired.
Subsequently, the following vehicle is detected from the rear image captured by each of the left rear camera 10L, the right rear camera 10R, and the rear camera 12 (S102). As a method of detecting the following vehicle, a known method using pattern matching can be applied.

Then, it is determined whether or not the following vehicle is detected (S103). If the following vehicle is detected (S103: yes), headlight mask processing is started (S150). Although the details will be described later, with the headlight mask processing, when the following vehicle lights the headlight, a portion where the headlight appears in the rear image fly white and the surroundings are seen It is a process executed to avoid becoming difficult.
On the other hand, when the following vehicle is not detected (S103: no), headlight mask processing is omitted.

Subsequently, in the rear image (photographed by the left rear camera 10L, the right rear camera 10R, and the rear camera 12), the rear situation display device 100 causes the brightness of the image to be equal to or higher than a predetermined first threshold in portions other than the following vehicle. It is determined whether a high brightness area exists (S104). Here, the first threshold is set to a large value such that the rear image is almost white.
As a result, if the high brightness area exists (S104: yes), the standard mask is read from the storage unit 104, and the size of the standard mask is changed according to the size of the high brightness area (S105) Correction using the standard mask to reduce the brightness of the high brightness area (S106).

  FIG. 4 conceptually shows a standard mask for reducing the brightness of the high brightness area other than the headlight of the following vehicle. In the standard mask, the reduction rate of luminance is set in accordance with the coordinates of the XY plane centered on the origin O. The reduction rate of the luminance is set to be highest at the origin O and to be gradually lower as the distance from the origin O increases. In FIG. 4, in order to show that the reduction rate decreases as going away from the origin O, the cross section is shown in the YZ plane and the XZ plane.

In S105 of FIG. 3, the size of the high brightness area present in the rear image is detected, and the size (diameter D1 in FIG. 4) of the standard mask is changed so as to just cover the high brightness area. Then, in S106, the standard mask is applied to the high brightness area in the rear image, and the brightness in the rear image is reduced at the reduction rate set in the standard mask. When a plurality of high brightness areas are detected in the rear image (S104: yes), such processing is performed for each of the detected high brightness areas.
As described above, since the standard mask is set so that the reduction rate of luminance decreases as moving away from the origin O, the area where the luminance is reduced using the standard mask and the luminance outside the area are not reduced The luminance of the high luminance region can be naturally reduced so that the boundary with the region is not noticeable.
On the other hand, when the high brightness area is not detected in the rear image (S104: no), the processing (S105, S106) of correcting the brightness of the rear image using the standard mask is omitted.

  Thereafter, the rear image is output to the left rear monitor 20L, the right rear monitor 20R, and the rear monitor 22 (S107). As a result, the driver of the vehicle 1 can recognize the situation behind the vehicle 1 by confirming the images displayed on the left rear monitor 20L, the right rear monitor 20R, and the rear monitor 22.

Then, it is judged whether or not the display of the rear situation is ended (S108), and when the display is not ended (S108: no), the process returns to the beginning and the rear image is acquired again (S101). Thereafter, the series of processes described above are repeated.
On the other hand, when the display of the rear situation is ended (S108: yes), the rear situation display processing of FIG. 3 is ended.

C. Headlight mask processing:
FIG. 5 shows a flowchart of headlight mask processing that is performed when a following vehicle is detected from the rear image. This process is a process executed by the rear situation display device 100 during the above-described rear situation display process.
When the headlight mask process (S150) is started, one succeeding vehicle is selected from the rear image (S151). As described above, since the headlight mask process is started when the following vehicle is detected in the rear image, there is always one following vehicle in the rear image.

Subsequently, it is determined whether a high brightness area having a brightness value equal to or more than a predetermined second threshold value exists in the area where the selected following vehicle appears (S152). The second threshold in the present embodiment is described as being set to a value larger than the first threshold used to detect the high brightness area in the rear state display process of FIG. The second threshold may be set to the same value as the first threshold.
As a result, if there is a region of higher luminance than the second threshold in the following vehicle (S152: yes), it is considered that the headlight illuminated by the following vehicle is shown in that region Be Therefore, the size of the headlamp mask for reducing the luminance of the headlamp is changed according to the size of the following vehicle (S153). The headlight mask is stored in the storage unit 104. Also, the size of the following vehicle is detected in advance in S102 of FIG.
In the present embodiment, the position of the headlight of the following vehicle is detected by detecting the region of higher luminance than the second threshold in the following vehicle, but the outline (or width and The position of the headlight may be estimated from the height), and it may be determined whether the brightness in a predetermined range including the position is higher than the second threshold.

A mask for a headlight is conceptually shown in FIG. Similarly to the standard mask shown in FIG. 4, the reduction rate of the luminance is set in accordance with the coordinates of the XY plane centered on the origin point O in the headlight mask. In FIG. 6 as well, as in FIG. 4 described above, in order to show how the reduction rate of luminance set in the mask changes, it is displayed in a state in which a cross section is taken on the YZ plane and the XZ plane. .
As is clear from the cross-sectional shape of the headlight mask shown in FIG. 6, the brightness of the headlight mask decreases with distance from the origin O as in the above-described standard mask at locations far from the origin O. The rate is set to be gradually lower. For this reason, even when the headlight mask is used, the boundary between the area where the brightness is reduced using the headlight mask and the area where the brightness outside thereof is not reduced is not noticeable. The brightness of the brightness area can be reduced.

However, unlike the standard mask, the mask for headlights is set to have a significantly smaller reduction rate of luminance in the range from the origin O to the diameter D2 than in the outside thereof. In this embodiment, the range from the origin O to the diameter D2 corresponds to the "first region" in the present invention, and the range outside the diameter D2 and the diameter D1 is the "second region" in the present invention Corresponds to
Further, at the position of the diameter D2, the reduction rate is set to change discontinuously. In the example shown in FIG. 6, it has been described that the luminance reduction rate is set to a value other than 0 even in the area within the diameter D2 centered on the origin O. However, in the area within the diameter D2, the reduction rate of luminance may be set to zero.
Further, in the mask for a headlamp according to the present embodiment, a range in which the reduction rate is constant is provided outside the region of the diameter D2 where the reduction rate of luminance decreases discontinuously, and from the origin O on the outside thereof. As the distance is larger, the region in which the reduction rate of the luminance gradually decreases is set.

  FIG. 7 conceptually shows how the size of the headlight mask is determined in accordance with the size of the following vehicle. In the illustrated example, the diameter D1 of the headlight mask and the diameter D2 of the region where the reduction rate of the luminance is low at the central portion are preset in association with the width W of the following vehicle. Further, the diameter D1 and the diameter D2 are set to increase as the width W of the following vehicle increases. In the storage unit 104, such correspondence between the diameter D1 and the diameter D2 corresponding to the width W of the following vehicle is stored in advance.

In S153 of FIG. 5, when the size (in this case, the width W) of the following vehicle is received, the diameter D1 and the diameter D2 are read out by referring to the correspondence stored in the storage unit 104, and Change the size of the headlight mask.
If the width W of the following vehicle can not be detected, the diameter D1 and the diameter D2 can be determined using the height of the following vehicle instead of the width W of the following vehicle. That is, the diameter D1 and the diameter D2 corresponding to the height of the following vehicle may be stored in advance in the storage unit 104, and the diameter D1 and the diameter D2 may be determined by referring to this correspondence.

  Here, according to the size of the following vehicle, it has been described that the diameter D1 and the diameter D2 of the headlight mask are determined separately. However, the ratio of the diameter D1 to the diameter D2 may be fixed in advance, and the other diameter may be determined by determining the diameter D1 (or the diameter D2) according to the size of the following vehicle. In this case, since the other can be determined only by determining one of the diameters, processing can be speeded up.

Then, in S154, the headlight mask is applied to the high brightness area of the following vehicle to perform processing for reducing the brightness of the high brightness area at the reduction rate set for the headlight mask.
On the other hand, when the high brightness area is not detected in the following vehicle (S152: no), the process (S153, S154) of correcting the brightness of the rear image using the headlight mask is omitted.

  Subsequently, it is determined whether or not all the following vehicles in the rear image have been selected (S155), and if there is an unselected following vehicle remaining (S155: no), the process returns to the beginning and a new following One vehicle is selected (S151). On the other hand, if all the following vehicles have been selected (S155: yes), the headlight mask process of FIG. 5 is ended, and the process is returned to the rear state display process of FIG.

  The image displayed by the back condition display process of a present Example is illustrated by FIG. Here, although the image displayed on the left rear monitor 20L is described as an example, the items described below apply to the images displayed on the right rear monitor 20R and the rear monitor 22 in the same manner. Maru.

FIG. 8A illustrates the case where the image obtained by the left rear camera 10L is displayed as it is (without reducing the brightness) on the left rear monitor 20L. When the following vehicle turns on the headlights, the left rear camera 10L takes a picture of the following vehicle from the front, so that an area around the headlight becomes a white image.
Also, as shown in the figure, when a plurality of following vehicles overlap, the area where the image flew white centering on the headlights of the following vehicles is connected, and how many following vehicles are shown, It is difficult to determine immediately.
Furthermore, since the portion of the headlight is dazzling, it is difficult to grasp the surrounding situation even in the region outside the portion.

FIG. 8 (b) illustrates an image in the case where the luminance is reduced by applying a standard mask to the portion where the headlights appear. When the standard mask is applied, the brightness of the portion where the headlight is captured is suppressed, so the headlight does not feel dazzling.
However, it is difficult to immediately determine that the entire image is dark and that there is a following vehicle or how many following vehicles are shown when the following vehicles overlap.

  The image displayed by the back condition display process of the present Example mentioned above is illustrated by FIG.8 (c). As described above, in the rear state display process, the headlight mask is applied to the portion where the headlight of the following vehicle is photographed to reduce the luminance. Furthermore, as shown in FIG. 6, this head mask is set to have a small reduction rate of luminance at the central portion. For this reason, as illustrated in FIG. 8C, since the high-brightness area remains in the portion where the headlights of the following vehicles appear, the driver can immediately recognize that the following vehicles exist. it can. Of course, if the high brightness area is large, the driver may feel dazzling to make it difficult to check the rear situation. However, as shown in FIG. 6, it is only a relatively narrow region of the diameter D2 that the reduction rate of luminance is set to a small value at the central portion of the headlamp mask. Therefore, the driver does not feel dazzling because only the central part of the headlights is brightly reflected even in the rear image.

  In addition, as shown in FIG. 6, in the headlamp mask of the present embodiment, the reduction ratio of luminance is set to change discontinuously from the center to the diameter D2. Therefore, the driver can easily recognize the position of the headlight because the boundary between the high-brightness area displayed small in the central part of the headlight and the low-brightness area outside the part can be clearly seen. It is possible to

  In addition, since the positions of the headlights on both sides of the following vehicle can be clearly identified, the driver of the vehicle 1 can immediately recognize the size of the following vehicle only by looking at the rear image. Furthermore, even when a plurality of following vehicles overlap and are displayed, since the headlights of the respective following vehicles are displayed without overlapping, it is possible to easily recognize how many following vehicles exist. Become.

  Furthermore, in the present embodiment, the size of the headlight mask (in particular, the diameter D2 of the central region) is set to be smaller as the size of the following vehicle is smaller. For this reason, the area of the high-intensity part displayed in a small size at the position of the headlight changes according to the size of the following vehicle, and the driver of the vehicle 1 follows the size of the high-intensity part. It becomes possible to easily recognize the size.

  As mentioned above, although a present Example was described, this invention is not limited to said Example and modification, It can implement in a various aspect in the range which does not deviate from the summary.

1 ... vehicle, 10 ... rear image acquisition unit, 10 L ... left rear camera,
10R ... right rear camera, 12 ... rear camera, 20 L ... left rear monitor,
20R ... right rear monitor, 22 ... rear monitor, 100 ... rear status display device,
101 ... rear image acquisition unit, 102 ... subsequent vehicle detection unit, 103 ... image correction unit,
104 ... storage unit, 105 ... image display unit.

Claims (7)

A rear situation display device (100) mounted on a vehicle (1) and displaying a situation behind the vehicle,
Rear image acquisition means (101) for acquiring a rear image obtained by photographing the rear of the vehicle using an on-vehicle camera (10L, 10R, 12) mounted on the vehicle;
A following vehicle detection means (102) for detecting a following vehicle from the rear image;
In the rear image, the brightness of the location where the headlight of the following vehicle is photographed is detected, and when the brightness exceeds a predetermined threshold, a predetermined area including the location where the headlight is photographed Image correction means (103) for correcting the rear image by reducing the brightness of the rear image;
An image display means (105) for displaying the rear image on a display screen mounted on the vehicle;
In the first area including the central portion of the headlight, the image correction unit may be configured to reduce the reduction rate of the luminance more than a second area provided surrounding the first area. Rear status display, which is a means to correct the The rear situation display device according to claim 1, wherein
A rear situation display device, wherein the rear image acquisition means acquires the rear image obtained by photographing the rear side from the side of the vehicle using the on-vehicle camera mounted on the side of the vehicle. The rear situation display device according to claim 1 or 2, wherein
A rear situation display device according to claim 1, wherein the image correction means corrects the rear image in a mode in which the degree of decrease in the brightness is suppressed toward the outside at least at the outer edge portion of the second area. The rear situation display device according to any one of claims 1 to 3, wherein
The image correction means is a means for correcting the rear image in a mode in which the degree of decreasing the brightness is changed discontinuously in a portion where the first area and the second area are in contact with each other. . The rear situation display device according to any one of claims 1 to 4, wherein
The following vehicle detection means is a means for detecting the size of the following vehicle on the rear image,
The image correction means is means for changing the size of the first area according to the size of the following vehicle to correct the rear image. Rear condition display device. The rear situation display device according to any one of claims 1 to 5, wherein
The image correction means is means for changing the size of the second area according to the size of the following vehicle to correct the rear image. Rear condition display device. A rear situation display method (S100) which is applied to a vehicle equipped with an on-vehicle camera and displays the situation behind the vehicle,
A first step (S101) of acquiring a rear image obtained by photographing a rear situation of the vehicle from the on-vehicle camera;
A second step (S102) of detecting a following vehicle from the rear image;
A third step (S152) of detecting a location where a headlight of the following vehicle is photographed in the rear image;
When the brightness of the portion where the headlight appears is greater than a predetermined threshold, the rear image is reduced by decreasing the brightness of the rear image in a predetermined area including the portion where the headlight appears. A fourth process (S154) for correction;
And a fifth step (S107) of displaying the rear image on the display screen mounted on the vehicle.
In the fourth step, in the first area including the central portion of the headlight, the reduction rate of the luminance is suppressed more than a second area provided to surround the first area. Backward situation display method which is a process of correcting

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