JP2019189081A - Image display device - Google Patents

Abstract

To display a proper image corresponding to a traveling scene of a vehicle.SOLUTION: An image display device (100) is mounted on a vehicle (1). The image display device comprises photographing means (10) which can automatically switch a daytime mode and a night mode according to the luminosity of a photographing place, and display means (30) for displaying a photographing image. The image display device further comprises acquisition means (21) for acquiring vehicle state information being information related to a state of a vehicle, and exposure adjustment means (13, 22) for adjusting exposure related to the photographing means on the basis of a plurality of pixel values corresponding to a plurality of pixels constituting a photometry area being a region of a part of the photographing image. The exposure adjustment means expand the photometry area when a prescribed condition is satisfied compared with the case where the prescribed condition is not satisfied.SELECTED DRAWING: Figure 1

Description

  The present invention relates to the technical field of image display devices.

  As this type of device, for example, a device that displays a captured image of a camera outside the vehicle on a dual display that includes a front display surface portion and a rear display surface portion that are positioned forward and backward in the user's line-of-sight direction. When displaying an image, there is a device that displays a higher brightness of the front side display unit so that an image showing the dangerous object can be seen in the front as the danger level of the dangerous object that is an obstacle to vehicle traveling shown in the captured image is higher. It has been proposed (see Patent Document 1). In addition, there is a technique described in Patent Document 2 as a related technique.

JP 2008-263325 A JP 2017-058600 A

  An image captured by an imaging device such as a camera changes in impression when the exposure setting of the imaging device (that is, the light receiving device) changes. In many cases, unintentional overexposure and underexposure occur in an image captured when the exposure setting of the image capturing apparatus is not appropriate. Unintentional overexposure and underexposure are not eliminated even when the brightness of the display (that is, the display device) is adjusted as in the technique described in Patent Document 1.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an image display device capable of displaying an appropriate image according to a traveling scene of a vehicle.

  An image display device according to an aspect of the present invention includes an imaging unit that can automatically switch between a daytime mode and a nighttime mode according to the brightness of an imaging location, and a display unit that displays a captured image captured by the imaging unit. And an image display device mounted on a vehicle, comprising an acquisition means for acquiring vehicle state information that is information relating to the state of the vehicle, and a photometric area that is a partial region of the captured image Exposure adjusting means for adjusting the exposure relating to the imaging means based on a plurality of pixel values respectively corresponding to the plurality of pixels to be performed, and the exposure adjusting means, when a predetermined condition is satisfied, Compared to the case where the condition is not satisfied, the photometry area is widened, and the predetermined condition is (I) (i) that the imaging means is in the night mode, and (ii) the vehicle speed (Iii) It is indicated that the ignition is switched from OFF to ON, or that the shift position is switched from the reverse position to the forward position or the parking position, and (II) (I) including that the imaging unit is switched from the daytime mode to the nighttime mode, and (ii) being within a predetermined time from the time when the imaging unit is switched from the daytime mode to the nighttime mode. Is.

It is a block diagram which shows the structure of the image display apparatus which concerns on embodiment. It is a figure which shows an example of the photometry area which concerns on embodiment, and an example of a display image. It is a figure which shows an example of the identification logic in the photometry area setting part which concerns on embodiment. It is a flowchart which shows the photometry area setting process which concerns on embodiment.

  An embodiment according to an image display device will be described with reference to FIGS. 1 to 3.

(Constitution)
The configuration of the image display apparatus according to the embodiment will be described with reference to FIG. FIG. 1 is a block diagram illustrating a configuration of an image display apparatus according to the embodiment.

  In FIG. 1, an image display device 100 is mounted on a vehicle 1. The image display device 100 includes a camera 10, a control unit 20, and a display unit 30.

  The camera 10 images the surroundings of the vehicle 1. The camera 10 includes an imaging mechanism 11, an image output unit 12, an automatic exposure (AE) function unit 13 (hereinafter referred to as “AE function unit 13” as appropriate), a mode selection unit 14, and an illuminance sensor 15. It is configured.

  The imaging mechanism 11 includes, for example, a lens, a diaphragm mechanism, a shutter, a light receiving element, and the like. The image output unit 12 outputs the captured image captured by the imaging mechanism 11 to the AE function unit 13 and the control unit 20.

  The AE function unit 13 acquires a plurality of luminance values respectively corresponding to a plurality of pixels constituting an area corresponding to the photometric area in the captured image, and obtains an average luminance value that is an average value of the plurality of luminance values. . The AE function unit 13 compares the average luminance value with the reference value. (I) If the average luminance value is larger than the reference value, the exposure value related to the imaging mechanism 11 is automatically adjusted so that the average luminance value becomes smaller. (Ii) If the average luminance value is smaller than the reference value, the exposure value related to the imaging mechanism 11 is automatically adjusted so that the average luminance value is increased. The photometric area will be described later.

  The mode selection unit 14 selects one imaging mode from a plurality of predetermined imaging modes based on the output of the illuminance sensor 15 (that is, based on the brightness of the imaging location), and selects the one imaging mode. For example, the imaging mechanism 11 is controlled so as to have an aperture value, a shutter speed, a gain (for example, equivalent to ISO sensitivity), and the like corresponding to the imaging mode.

  In the present embodiment, it is assumed that a daytime mode and a nighttime mode are included in the plurality of imaging modes. The shutter speed in the night mode is set slower than the shutter speed in the day mode. In the night mode, night visibility is improved by setting a gain larger than that in the day mode or by setting a γ curve that emphasizes a low-luminance video.

  The control unit 20 includes a vehicle information acquisition unit 21, a photometric area setting unit 22, and a display control unit 23 as processing blocks that are logically realized therein or as processing circuits that are physically realized. Yes.

  The vehicle information acquisition unit 21 generates vehicle information based on, for example, outputs of the shift sensor 41 and the vehicle speed sensor 42 mounted on the vehicle 1 and a signal indicating the state of the ignition switch 43.

  The photometric area setting unit 22 estimates the travel scene of the vehicle 1 based on the vehicle information generated by the vehicle information acquisition unit 21 and the imaging mode selected by the mode selection unit 14 (the estimation method will be described later). The photometric area setting unit 22 sets a photometric area according to the AE function unit 13 according to the estimated traveling scene.

  The display control unit 23 displays the captured image output from the image output unit 12 on the display unit 30. In the present embodiment, the display control unit 23 extracts a display area that is an area to be displayed on the display unit 30 from the captured image (that is, trims) from the captured image, and displays the display area on the display unit 30. Shall.

(Problems of automatic exposure function)
Here, the problem of the automatic exposure function will be described. For example, an image captured in a daytime multi-story parking lot may include a relatively bright area due to external light. At this time, even if the captured image is entirely dark (that is, even when the average luminance value related to the captured image is relatively small), the proportion of the relatively bright area in the photometric area is relatively large Then, the average luminance value related to the photometric area (corresponding to the average luminance value obtained by the AE function unit 13 described above) becomes relatively large. Then, the exposure value may not be appropriately adjusted due to the relatively large average luminance value relating to the photometric area.

  As a countermeasure to the above problem, it is conceivable to set the photometric area relatively wide, for example, the photometric area is set so as to include the entire captured image. However, when the exposure value is set to be relatively large by the automatic exposure function due to the relatively small average luminance value relating to the photometric area (in this case, the entire captured image in this case) when traveling at night, for example, other vehicles There is a possibility that halation may occur due to the light of the headlight.

(Photometry area)
A photometric area according to the AE function unit 13 will be described with reference to FIG. FIG. 2 is a diagram illustrating an example of a photometric area and an example of a display image according to the embodiment.

  FIG. 2A is a diagram illustrating an example of a photometric area. In FIG. 2A, a dotted line frame A and a broken line frame B indicate photometric areas, respectively. Hereinafter, the dotted frame A is referred to as “photometry area A”, and the dashed frame B is referred to as “photometry area B”.

  The photometric area A corresponds to a display area to be displayed on the display unit 30 in the captured image. The position of the photometric area A is not limited to the position shown in FIG. 2A, and may be set as appropriate. Further, for example, when the display control unit 23 has a function of enlarging and displaying a part of the image displayed on the display unit 30 (that is, when the display region is variable), the change of the display region is performed. The photometry area A is also changed accordingly.

  The photometric area B corresponds to an area of the captured image that includes the display area and is wider than the display area. Note that the photometric area B is set to be wider than the maximum range of the display area even when the display area is variable.

  In the present embodiment, in order to suppress the occurrence of the problems listed in “Problems of the automatic exposure function”, either one of the photometric areas A and B is selected by the photometric area setting unit 22 according to the traveling scene of the vehicle 1. It is automatically set (that is, photometry areas A and B are automatically switched). A specific description of the relationship between the traveling scene of the vehicle 1 and the photometric area will be given later.

  For example, when the exposure value is adjusted based on the average luminance value related to the photometric area A for an image captured inside a multi-story parking lot in the daytime, for example, as shown in FIG. It will be unclear. On the other hand, when the exposure value is adjusted based on the average luminance value related to the photometric area B for the image captured inside the daytime multilevel parking lot, for example, as shown in FIG. Compared with (b), a clear captured image is obtained. For this reason, the photometry area setting part 22 sets the photometry area which concerns on the AE function part 13 to the photometry area B, when the vehicle 1 is drive | working the inside of a covered parking lot, such as a multilevel parking lot, for example.

(Driving scene estimation)
A method of estimating a traveling scene in the photometric area setting unit 22 will be described with reference to FIG. FIG. 3 is a diagram illustrating an example of identification logic in the photometric area setting unit according to the embodiment. In addition, the graph of FIG. 3 has shown the time change of each of an ignition switch (IG), a vehicle speed, a shift position, and a camera scene.

  The photometric area setting unit 22 is indicated by the vehicle information generated by the vehicle information acquisition unit 21, for example, the ignition switch, the time change of the vehicle 1 and the shift position, and the imaging mode selected by the mode selection unit 14. The travel scene of the vehicle 1 is estimated on the basis of the time change. Specifically, the photometry area setting unit 22 determines whether the ignition switch, the vehicle speed of the vehicle 1, the shift position, and the time change of each camera scene satisfy a predetermined condition, and estimates a driving scene from the determination result. To do.

  As shown in FIG. 3 (a), (i) the ignition switch is changed from OFF to ON, (ii) the vehicle 1 is maintained at a low speed (stopped, that is, including 0 km / h), (Iii) When the shift position is maintained at the forward position (for example, D) or the parking position (P), and (iv) the imaging mode is maintained at the night mode, the photometric area setting unit 22 displays the traveling scene as, for example, a three-dimensional Presumed to be in a covered parking lot such as a parking lot. Note that (i) to (iv) correspond to the above determination results. The same applies to “estimation of driving scene”.

  As shown in FIG. 3B, (i) the state of the ignition switch is kept ON, (ii) the vehicle 1 is kept at a low speed (stopped, that is, including 0 km / h), (iii) ) When the shift position is changed from the reverse position (R) to the forward position (for example, D) or the parking position (P), and (iv) the imaging mode is maintained in the night mode, the photometry area setting unit 22 Is estimated to be in a covered parking lot such as a multilevel parking lot.

  As shown in FIG. 3C, (i) the ignition switch state is maintained ON, (ii) the shift position is maintained at the forward position (eg, D), and (iii) the imaging mode is changed from daytime mode to nighttime. When the mode is changed, the photometry area setting unit 22 estimates that the traveling scene is near the entrance in the tunnel.

  As shown in FIG. 3D, (i) the state of the ignition switch is maintained ON, (ii) the vehicle speed of the vehicle 1 is not maintained at a low speed, and (iii) the shift position is set to the forward position (for example, D), and (iv) when the imaging mode is maintained in the night mode (in other words, when it does not correspond to any of the above (a) to (c)), the photometry area setting unit 22 Is estimated to be traveling at night.

(Metering area setting process)
The photometry area setting process in the photometry area setting unit 22 will be described with reference to the flowchart of FIG.

  In FIG. 4, the photometric area setting unit 22 determines whether or not the imaging mode selected by the mode selection unit 14 is the night mode (step S101). If it is determined in step S101 that the mode is not night mode (step S101: No), the photometry area setting unit 22 sets the photometry area related to the AE function unit 13 to photometry area A (see FIG. 2A). Set (step S110).

  If it is determined that the night mode is selected in the process of step S101 (step S101: Yes), the photometry area setting unit 22 starts from the current time within the first period before the present time, and the imaging mode is changed from the daytime mode. It is determined whether or not the night mode has been changed (step S102). The “first period” is, for example, several seconds to ten and several seconds, and is typically set as a variable value according to the vehicle speed of the vehicle 1.

  In the process of step S102, when it is determined that the imaging mode is changed from the daytime mode to the nighttime mode within the first period (step S102: Yes), the photometry area setting unit 22 sets the traveling scene near the entrance in the tunnel. (Step S103), the photometry area according to the AE function unit 13 is set to the photometry area B (see FIG. 2A) (step S108).

  If it is determined in step S102 that the imaging mode has not been changed from the daytime mode to the nighttime mode within the first period (step S102: No), the photometric area setting unit 22 determines that the vehicle speed of the vehicle 1 is a threshold. It is determined whether or not the speed is below (step S104). The “threshold speed” is set as a speed regarded as a slow speed, such as several kilometers per hour.

  In the process of step S104, when it is determined that the vehicle speed of the vehicle 1 is greater than the threshold speed (step S104: No), the photometry area setting unit 22 estimates that the travel scene is night travel (step S109), and the AE function. The photometric area according to the unit 13 is set to the photometric area A (see FIG. 2A) (step S110).

  In the process of step S104, when it is determined that the vehicle speed of the vehicle 1 is equal to or lower than the threshold speed (step S104: Yes), the photometry area setting unit 22 starts from the present and within the second period before the present, It is determined whether or not the state of the ignition switch has been changed from OFF to ON (that is, whether or not the ignition has been turned ON) (step S105). The “second period” is set, for example, from several seconds to several tens of seconds.

  In the process of step S105, when it is determined that the ignition switch state has been changed from OFF to ON within the second period (step S105: Yes), the photometry area setting unit 22 sets the travel scene to a covered parking lot. (Step S107), and the photometry area related to the AE function unit 13 is set to the photometry area B (see FIG. 2A) (step S108).

  In the process of step S105, when it is determined that the ignition switch state has not been changed from OFF to ON within the second period (step S105: No), the photometry area setting unit 22 It is determined whether or not the shift position has been changed from the reverse position (R) to the forward position (for example, D) or the parking position (P) within the previous third period (step S106). The “third period” is set, for example, from several seconds to several tens of seconds.

  If it is determined in step S106 that the shift position has been changed from the reverse position (R) to the forward position (eg, D) or the parking position (P) within the third period (step S106: Yes), photometry is performed. The area setting unit 22 estimates the traveling scene as a covered parking lot (step S107), and sets the photometric area according to the AE function unit 13 to the photometric area B (see FIG. 2A) (step S108). .

  In the process of step S106, when it is determined that the shift position has not been changed from the reverse position (R) to the forward position (eg, D) or the parking position (P) within the third period (step S106: No). The photometry area setting unit 22 estimates that the travel scene is night driving (step S109), and sets the photometry area according to the AE function unit 13 to the photometry area A (see FIG. 2A) (step S110).

(Technical effect)
In the image display device 100, the travel scene of the vehicle 1 is estimated by the photometric area setting unit 22, and the photometric area related to the AE function unit 13 is set according to the estimated travel scene. Then, the exposure value related to the imaging mechanism 11 is adjusted by the AE function unit 13 based on the average luminance value related to the photometric area. For this reason, it can be expected that the exposure value related to the imaging mechanism 11 is appropriately adjusted according to the traveling scene of the vehicle 1. Therefore, according to the image display device 100, it is possible to display an appropriate image according to the traveling scene of the vehicle 1.

  Specifically, for example, when the vehicle 1 is traveling near a covered parking lot or an entrance in a tunnel, a relatively wide photometric area B (see FIG. 2A) is measured by the AE function unit 13. Set as an area. In the vicinity of a parking lot with a roof or an entrance in a tunnel, since the ratio of pixels having a relatively small luminance value in the entire captured image is relatively large, the average luminance value related to the photometric area is often relatively small. As a result, it can be expected that the exposure value related to the imaging mechanism 11 is increased and a relatively clear captured image is obtained (see FIG. 2C).

  For example, when the vehicle 1 is traveling on a general road at night, a relatively narrow photometric area A (see FIG. 2A) is set as the photometric area related to the AE function unit 13. At night, for example, light from other vehicles, such as headlights and streetlights, often appears in the captured image. Therefore, if the photometric area is relatively small, the proportion of pixels with relatively large luminance values in the photometric area is compared. Increase. For this reason, the average luminance value related to the photometric area is relatively large. As a result, it can be expected that the exposure value related to the imaging mechanism 11 is reduced, and for example, a captured image in which the occurrence of halation is suppressed is obtained.

  Various aspects of the invention derived from the embodiments described above will be described below.

  An image display device according to an aspect of the invention includes an imaging unit that can automatically switch between a daytime mode and a nighttime mode according to the brightness of an imaging location, and a display unit that displays a captured image captured by the imaging unit. And an image display device mounted on a vehicle, wherein the acquisition unit acquires vehicle state information that is information relating to the state of the vehicle, and a photometric area that is a partial region of the captured image. Exposure adjusting means for adjusting exposure according to the imaging means based on a plurality of pixel values respectively corresponding to a plurality of pixels, and the exposure adjusting means, when a predetermined condition is satisfied, the predetermined condition Compared with the case where is not satisfied, the photometric area is widened, and the predetermined condition is (I) (i) that the imaging means is in the night mode, and (ii) the speed of the vehicle based on the vehicle state information. But (Iii) It is indicated that the ignition is switched from OFF to ON, or that the shift position is switched from the reverse position to the forward position or the parking position, and (II) ( i) that the imaging means has been switched from the daytime mode to the nighttime mode, and (ii) that the imaging means has been within a predetermined time since the switching from the daytime mode to the nighttime mode. It is.

  In the above-described embodiment, “camera 11” corresponds to an example of “imaging unit”, “display unit 30” corresponds to an example of “display unit”, and “vehicle information acquisition unit 21” corresponds to “acquisition unit”. “AE function unit 13” and “photometry area setting unit 22” correspond to an example of “exposure adjusting means”. The “luminance value”, “threshold speed”, and “first period” according to the above-described embodiment correspond to examples of “pixel value”, “predetermined value”, and “predetermined time”, respectively.

  According to the image display device, the size of the photometric area is changed depending on whether or not a predetermined condition is satisfied. Here, when a predetermined condition is satisfied, it corresponds to a specific traveling scene. On the other hand, when the predetermined condition is not satisfied, it corresponds to a traveling scene other than the specific traveling scene. That is, changing the size of the photometric area depending on whether or not the predetermined condition is satisfied is synonymous with changing the size of the photometric area depending on the traveling scene.

  The content of the above (I) included in the predetermined condition is, for example, an imaging mode when the vehicle travels at a relatively low speed in a relatively dark place where outside light is blocked by a building such as a covered parking lot. And vehicle condition. The content of the above (II) included in the predetermined condition is that imaging is performed when the vehicle moves from a place where external light hits the vehicle to a relatively dark place where the external light is blocked by a building, for example, in a tunnel. Corresponds to mode and vehicle status.

  In these cases, it is often possible to obtain a captured image that is relatively dark overall, but partially includes a relatively bright region. At this time, if the photometric area is relatively small, the proportion of the relatively bright area in the photometric area may be relatively large. Then, although the captured image is relatively dark as a whole, the exposure adjustment unit may erroneously recognize that the captured image is a relatively bright captured image, and the exposure related to the imaging unit may not be adjusted appropriately.

  As described above, when the predetermined condition is satisfied, if the photometry area is widened compared to the case where the predetermined condition is not satisfied, the captured image is relatively dark on the whole, and a relatively light area is partially obtained. Even if it exists, it can suppress that the exposure adjustment means misrecognizes the overall brightness of the captured image. Therefore, according to the image display device, it is possible to appropriately adjust the exposure according to the imaging device according to the traveling scene of the vehicle and display an appropriate image according to the traveling scene.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and an image display device with such a change Is also included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 10 ... Camera, 11 ... Imaging mechanism, 12 ... Image output part, 13 ... Automatic exposure function part, 14 ... Mode selection part, 15 ... Illuminance sensor, 20 ... Control unit, 21 ... Vehicle information acquisition part, 22 DESCRIPTION OF SYMBOLS ... Photometry area setting part 23 ... Display control part 30 ... Display part 41 ... Shift sensor 42 ... Vehicle speed sensor 43 ... Ignition switch 100 ... Image display apparatus

Claims (1)

An image display mounted on a vehicle, comprising: an imaging unit that can automatically switch between a daytime mode and a nighttime mode according to the brightness of the imaging location; and a display unit that displays a captured image captured by the imaging unit. A device,
Obtaining means for obtaining vehicle state information which is information relating to the state of the vehicle;
Exposure adjusting means for adjusting exposure according to the imaging means based on a plurality of pixel values respectively corresponding to a plurality of pixels constituting a photometric area which is a partial area of the captured image;
With
The exposure adjusting means widens the photometric area when a predetermined condition is satisfied, compared to when the predetermined condition is not satisfied,
The predetermined condition is:
(I) (i) The imaging means is in the night mode, the vehicle state information indicates that (ii) the speed of the vehicle is below a predetermined value, and (iii) the ignition is switched from OFF to ON. Or that the shift position has been switched from the reverse position to the forward position or the parking position,
And
(II) (i) that the imaging means has been switched from the daytime mode to the nighttime mode, and (ii) that the imaging means has been within a predetermined time from the time point when the daytime mode has been switched to the nighttime mode,
An image display device comprising: