Illuminance estimation device

Abstract

To provide an illuminance estimator that can estimate illuminance when a vehicle enters the inside of a structure.SOLUTION: An illuminance estimator 30 is a device that estimates the illuminance which is the brightness of the surroundings of a vehicle 10. The illuminance estimator 30 executes: acquiring front images which are images of the front of the vehicle; acquiring the luminance of a road surface area which is an area of a road surface on which the vehicle 10 travels, out of the front images; analyzing the front images to determine whether or not the vehicle 10 enters an inside of a structure that the vehicle 10 can enter; and acquiring a value corresponding to the luminance of the road surface area as the illuminance when it is determined that the vehicle enters the inside of the structure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an illuminance estimation device that estimates illuminance, which is the brightness of the surroundings of a vehicle, based on an image captured of the area ahead of the vehicle. [Background technology]

[0002] Patent Document 1 discloses an example of a control device that automatically turns on the vehicle's lights based on an image of the area ahead of the vehicle captured by an on-board camera. Specifically, the control device determines whether to automatically turn on the lights based on the brightness of a roadway area, which is an area in the image that shows the road on which the vehicle is traveling, and the brightness of an upper sky area, which is an area of ​​the sky above the roadway area. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-75304 Summary of the Invention [Problem to be solved by the invention]

[0004] Consider a control device that automatically turns on lights using illuminance estimated based on the image described above. The luminance of the sky region, which is the region of the image showing the sky, is less affected by light sources such as the sun than the luminance of the road surface region, which is the region showing the road. Therefore, it is preferable for the control device to estimate illuminance based on the luminance of the sky region.

[0005] However, when a vehicle enters a structure such as a covered parking lot or a tunnel, the sky may not be visible in the image. In such cases, the control device cannot obtain the luminance of the sky area, which may cause problems in estimating the illuminance. [Means for solving the problem]

[0006] An illuminance estimation device for solving the above problem is a device that estimates illuminance, which is the brightness around a vehicle. The illuminance estimation device performs the following operations: acquires a front image that is an image in front of the vehicle; acquires the luminance of a road surface area in the front image that is an area showing the road surface on which the vehicle is traveling; analyzes the front image to determine whether the vehicle will enter a structure that the vehicle can enter; and, if it is determined that the vehicle will enter the structure, acquires a value corresponding to the luminance of the road surface area as the illuminance. [Effects of the Invention]

[0007] The above-described illuminance estimation device has an effect of being able to estimate illuminance when a vehicle enters the interior of a structure. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a vehicle equipped with an illuminance estimation device and a front camera according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing an example of a forward image captured by the forward camera of FIG. [Figure 3] FIG. 3 is a schematic diagram showing an example of a forward image captured by the forward camera of FIG. [Figure 4] FIG. 4 is a flowchart showing the processing executed by the illumination estimation device of FIG. [Figure 5] FIG. 5 is a flowchart showing the processing executed by the illumination estimation device of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of an illumination estimation device will be described below with reference to FIGS. FIG. 1 illustrates a vehicle 10 equipped with an illuminance estimation device 30. The vehicle 10 further includes a front camera 11 and a light control device 20. The front camera 11 is installed in the front of the passenger compartment of the vehicle 10. Therefore, the front camera 11 can capture an image of the area in front of the vehicle Xa from its installation position on the vehicle 10. The image captured by the front camera 11 is referred to as a "front image IMG." The front camera 11 sequentially transmits data of the front image IMG to the illuminance estimation device 30.

[0010] The illuminance estimation device 30 estimates the illuminance ILL, which is the brightness around the vehicle 10. The illuminance estimation device 30 has an image recognition device 31 and an illuminance acquisition device 41. The image recognition device 31 analyzes the forward image IMG indicated by the data received from the forward camera 11. The illuminance acquisition device 41 acquires the illuminance ILL based on the analysis result of the forward image IMG by the image recognition device 31.

[0011] The light control device 20 determines whether to automatically turn on the lights of the vehicle 10 based on the illuminance ILL estimated by the illuminance estimation device 30. For example, when the illuminance ILL becomes equal to or greater than the light-on determination illuminance while the lights are off, the light control device 20 automatically turns on the lights. On the other hand, when the illuminance ILL becomes less than the light-off determination illuminance while the lights are on, the light control device 20 automatically turns off the lights. In this case, the light-off determination illuminance is set to an illuminance equal to or less than the light-on determination illuminance.

[0012] <Front image> 2 and 3 each show an example of a forward image IMG. The forward image IMG shown in Fig. 2 shows the road surface on which the vehicle 10 is traveling and the sky. The area of ​​the forward image IMG that shows the road surface is called the "road surface area RR." The area of ​​the forward image IMG that shows the sky is called the "sky area RE." The forward image IMG shown in Fig. 2 includes both the road surface area RR and the sky area RE.

[0013] The forward image IMG shown in FIG. 3 shows the road surface on which the vehicle 10 is traveling and a tunnel, which is an example of a structure. The forward image IMG shows the vehicle 10 about to enter the tunnel. The "structure" here refers to an object configured so that the vehicle 10 can enter. Examples of structures include a tunnel and a self-driving covered parking lot. The forward image IMG shown in FIG. 3 includes a road surface area RR, but does not include a sky area RE.

[0014] <Image recognition device for illuminance estimation device> As shown in FIG. 1, the image recognition device 31 includes a processing circuit 32. An example of the processing circuit 32 is an electronic control device. In this case, the processing circuit 32 includes a CPU 33 and a memory 34. The memory 34 stores a control program executed by the CPU 33. When the CPU 33 executes the control program of the memory 34, the processing circuit 32 executes an analysis process for analyzing the forward image IMG. The details of the analysis process will be described later.

[0015] <Illuminance acquisition device for illuminance estimation device> As shown in Fig. 1, the illuminance acquisition device 41 includes a processing circuit 42. One example of the processing circuit 42 is an electronic control device. In this case, the processing circuit 42 includes a CPU 43 and a memory 44. The memory 44 stores a control program executed by the CPU 43. The CPU 43 executes the control program in the memory 44, causing the processing circuit 42 to execute an illuminance acquisition process for acquiring the illuminance ILL. The details of the illuminance acquisition process will be described later.

[0016] Hereinafter, the processing circuit 32 of the image recognition device 31 will be referred to as the "first processing circuit 32," and the processing circuit 42 of the illuminance acquisition device 41 will be referred to as the "second processing circuit 42." <Analysis processing> 4, the analysis processing executed by the image recognition device 31 will be described. In the image recognition device 31, the CPU 33 executes the control program in the memory 34, and the first processing circuit 32 repeatedly executes the analysis processing at each predetermined control cycle.

[0017] In step S11, the first processing circuit 32 acquires data of the forward image IMG. In the following step S13, the first processing circuit 32 calculates a sky area occupancy ratio EOC, which is the occupancy ratio of the sky area RE in the currently acquired forward image IMG. The first processing circuit 32 calculates a road area occupancy ratio ROC, which is the occupancy ratio of the road area RR in the currently acquired forward image IMG. For example, the first processing circuit 32 uses a known image recognition technology to extract the sky area RE from the forward image IMG and calculates the area of ​​the extracted sky area RE. The first processing circuit 32 then calculates the area of ​​the sky area RE relative to the total area of ​​the forward image IMG as the sky area occupancy ratio EOC. Similarly, the first processing circuit 32 uses a known image recognition technology to extract the road area RR from the forward image IMG and calculates the area of ​​the extracted road area RR. The first processing circuit 32 then calculates the area of ​​the road area RR relative to the total area of ​​the forward image IMG as the road area occupancy ratio ROC.

[0018] In the next step S15, the first processing circuit 32 calculates the average luminance LAVES of the sky region RE as the luminance of the sky region RE. For example, the first processing circuit 32 divides the sky region RE of the forward image IMG into multiple divided regions. The first processing circuit 32 calculates the luminance of each of the multiple divided regions. The first processing circuit 32 then calculates the average value of the luminance of the multiple divided regions as the average luminance LAVES of the sky region RE.

[0019] Next, in step S17, the first processing circuit 32 calculates the average luminance LAVRS of the road surface region RR as the luminance of the road surface region RR. For example, the first processing circuit 32 divides the road surface region RR of the forward image IMG into a plurality of divided regions. The first processing circuit 32 calculates the luminance of each of the plurality of divided regions. Then, the first processing circuit 32 calculates the average value of the luminance of the plurality of divided regions as the average luminance LAVRS of the road surface region RR.

[0020] Then, in step S19, the first processing circuit 32 performs a correction process for the average luminances LAVES and LAVRS calculated in steps S15 and S17. For example, the first processing circuit 32 corrects the average luminances LAVES and LAVRS based on the current time of day, season, weather, etc. For example, if the road surface is covered in snow, the average luminance LAVRS of the road surface area RR is likely to be high, so the first processing circuit 32 corrects and decreases the average luminance LAVRS of the road surface area RR. For example, if the sky is reddish due to a sunset, the average luminance LAVES of the sky area RE is likely to be high, so the first processing circuit 32 corrects and decreases the average luminance LAVRS of the sky area RE.

[0021] In the next step S21, the first processing circuit 32 analyzes the forward image IMG to determine whether or not the vehicle 10 will enter the interior of a structure. For example, the first processing circuit 32 can determine that the vehicle 10 will enter the interior of a structure when the following conditions (A1) and (A2) are satisfied. In this case, the first processing circuit 32 determines that the vehicle 10 will not enter the interior of a structure when at least one of the following conditions (A1) and (A2) is not satisfied.

[0022] (A1) The structure is visible in the forward image (IMG). (A2) The distance from the vehicle 10 to the structure is less than the judgment distance. If the first processing circuit 32 determines that the vehicle 10 will enter the interior of the structure (S21: YES), the process proceeds to step S23. On the other hand, if the first processing circuit 32 determines that the vehicle 10 will not enter the interior of the structure (S21: NO), the process proceeds to step S25.

[0023] In step S23, the first processing circuit 32 sets the entry flag FLG to ON. The entry flag FLG is a flag that is set to ON when it is determined that the vehicle 10 will enter the interior of a structure. Thereafter, the first processing circuit 32 temporarily ends the analysis process.

[0024] In step S25, the first processing circuit 32 sets the entry flag FLG to OFF, and then the first processing circuit 32 temporarily ends the analysis process. <Illuminance acquisition process> 5, the illuminance acquisition process executed by the illuminance acquisition device 41 will be described. In the illuminance acquisition device 41, the CPU 43 executes the control program in the memory 44, causing the second processing circuit 42 to repeatedly execute the illuminance acquisition process at each predetermined control cycle.

[0025] In step S41, the second processing circuit 42 determines whether the entry flag FLG is set to ON. If the entry flag FLG is set to ON, it means that it has been determined that the vehicle 10 will enter the interior of the structure. If the entry flag FLG is not set to ON, it means that it has been determined that the vehicle 10 will not enter the interior of the structure. If the entry flag FLG is set to ON (S41: YES), the second processing circuit 42 shifts the processing to step S43. On the other hand, if the entry flag FLG is set to OFF (S41: NO), the second processing circuit 42 shifts the processing to step S45.

[0026] In step S43, the second processing circuit 42 acquires the average luminance LAVRS of the road surface area RR as the illuminance ILL. That is, when the second processing circuit 42 determines that the vehicle 10 is entering the interior of a structure, it acquires a value corresponding to the luminance of the road surface area RR as the illuminance ILL. Then, the second processing circuit 42 temporarily ends the illuminance acquisition process.

[0027] In step S45, the second processing circuit 42 determines whether the sky occupancy rate EOC is higher than the sky occupancy rate judgment value EOCth. It is estimated that the lower the sky occupancy rate EOC, the lower the correlation between the actual values ​​of luminance and illuminance of the sky region RE. Therefore, the sky occupancy rate judgment value EOCth is set as a criterion for determining whether the correlation between the actual values ​​of luminance and illuminance of the sky region RE is low. If the sky occupancy rate EOC is higher than the sky occupancy rate judgment value EOCth (S45: YES), the second processing circuit 42 proceeds to step S47. On the other hand, if the sky occupancy rate EOC is equal to or lower than the sky occupancy rate judgment value EOCth (S45: NO), the second processing circuit 42 proceeds to step S61.

[0028] In step S47, the second processing circuit 42 determines whether the average luminance LAVRS of the road surface area RR is higher than the road surface luminance judgment value LAVRSth. It is estimated that the higher the luminance of the road surface area RR, the lower the correlation between the luminance of the road surface area RR and the actual value of illuminance. Therefore, the road surface luminance judgment value LAVRSth is set as a criterion for determining whether the correlation between the luminance of the sky area RE and the actual value of illuminance is low. If the average luminance LAVRS of the road surface area RR is higher than the road surface luminance judgment value LAVRSth (S47: YES), the second processing circuit 42 proceeds to step S49. On the other hand, if the average luminance LAVRS is equal to or lower than the road surface luminance judgment value LAVRSth (S47: NO), the second processing circuit 42 proceeds to step S51.

[0029] In step S49, the second processing circuit 42 acquires the average luminance LAVES of the sky region RE as the illuminance ILL. That is, when it is determined that the vehicle 10 will not enter the interior of the structure, if both the sky occupancy rate EOC is higher than the sky occupancy rate judgment value EOCth and the average luminance LAVRS of the road surface region is higher than the road surface luminance judgment value LAVRSth, the second processing circuit 42 acquires a value corresponding to the luminance of the sky region RE as the illuminance ILL. Then, the second processing circuit 42 temporarily ends the illuminance acquisition process.

[0030] In step S51, the second processing circuit 42 acquires the average luminance LAVRS of the road surface area RR as the illuminance ILL. That is, when it is determined that the vehicle 10 will not enter the interior of the structure, if both the sky occupancy rate EOC is higher than the sky occupancy rate judgment value EOCth and the average luminance LAVRS of the road surface area is equal to or less than the road surface luminance judgment value LAVRSth, the second processing circuit 42 acquires a value corresponding to the luminance of the road surface area RR as the illuminance ILL. Then, the second processing circuit 42 temporarily ends the illuminance acquisition process.

[0031] In step S61, the second processing circuit 42 determines whether the road surface occupancy rate ROC is higher than the road surface occupancy rate judgment value ROCth. It is estimated that the lower the road surface occupancy rate ROC, the lower the correlation between the actual values ​​of luminance and illuminance of the road surface area RR. Therefore, the road surface occupancy rate judgment value ROCth is set as a criterion for determining whether the correlation between the actual values ​​of luminance and illuminance of the road surface area RR is low. If the road surface occupancy rate ROC is higher than the road surface occupancy rate judgment value ROCth (S61: YES), the second processing circuit 42 shifts the processing to step S63. On the other hand, if the road surface occupancy rate ROC is equal to or lower than the road surface occupancy rate judgment value ROCth (S61: NO), the second processing circuit 42 shifts the processing to step S65.

[0032] In step S63, the second processing circuit 42 calculates the illuminance ILL based on the last sky average luminance LAVESL, the last road surface average luminance LAVRSL, and the average luminance LAVRS of the road surface area RR. Specifically, the second processing circuit 42 calculates the illuminance ILL using the following relational expression (D1). The last sky average luminance LAVESL is the average luminance LAVES of the sky area RE at the time when the state where at least one of the determinations in step S45 and step S61 is negative (NO) changes to a state where both of the two determinations are positive (YES). The last road surface average luminance LAVRSL is the average luminance LAVRS of the road surface area RR at the time when the state where at least one of the determinations in step S45 and step S61 is negative (NO) changes to a state where both of the two determinations are positive (YES).

[0033] ILL = LAVESL × LAVES ÷ LAVRSL (D1) The "predetermined condition is met" when both the sky occupancy rate EOC is equal to or less than the sky occupancy rate judgment value EOCth and the road surface occupancy rate ROC is higher than the road surface occupancy rate judgment value ROCth. In this case, the luminance of the road surface area at the time when the predetermined condition is met is defined as the "predetermined road surface luminance." When the predetermined condition is met, the second processing circuit 42 calculates the illuminance ILL so that the illuminance ILL increases as the luminance of the current road surface area RR increases relative to the predetermined road surface luminance. Then, the second processing circuit 42 temporarily terminates the illuminance acquisition device.

[0034] In step S65, the second processing circuit 42 holds the illuminance ILL. Specifically, the second processing circuit 42 acquires the previous value of the illuminance ILL as the latest value of the illuminance ILL. The previous value of the illuminance ILL is the illuminance ILL acquired the previous time the illuminance acquisition process was executed. That is, when the second processing circuit 42 determines that the vehicle 10 will not enter the interior of the structure, if both the vacant space occupancy rate EOC is equal to or less than the vacant space occupancy rate judgment value EOCth and the road surface occupancy rate ROC is equal to or less than the road surface occupancy rate judgment value ROCth, the second processing circuit 42 holds the illuminance ILL. Then, the second processing circuit 42 temporarily ends the illuminance acquisition process.

[0035] <Action and effect> (1) When it is determined that the vehicle 10 is entering the interior of a structure, the illuminance estimation device 30 acquires the average luminance LAVRS of the road surface region RR as the illuminance ILL. That is, the illuminance estimation device 30 can estimate the illuminance ILL without using information about the sky region RE, i.e., the average luminance LAVES and the sky occupancy rate EOC of the sky region RE. Therefore, the illuminance estimation device 30 can estimate the illuminance when the vehicle 10 is entering the interior of a structure.

[0036] (2) When the illuminance estimation device 30 determines that the vehicle 10 is entering the interior of a structure, and it can determine that the sky occupancy rate EOC in the forward image IMG is relatively high, it estimates the illuminance ILL based on the luminance of the sky area RE or the luminance of the road area RR.

[0037] When the sky occupancy rate EOC is higher than the sky occupancy rate judgment value EOCth and the average luminance LAVRS of the road surface region RR is relatively high, it can be inferred that the current time is daytime. During the daytime, a large amount of light from the sun is incident on the road surface. Therefore, when the vehicle 10 is traveling during the daytime, it is inferred that the correlation between the luminance of the road surface region RR and the actual illuminance value is not very high. Therefore, when the sky occupancy rate EOC is higher than the sky occupancy rate judgment value EOCth and the average luminance LAVRS of the road surface region RR is higher than the road surface luminance judgment value LAVRSth, the illuminance estimation device 30 acquires the average luminance LAVES of the sky region RE as the illuminance ILL. In other words, the illuminance estimation device 30 estimates the illuminance ILL without using the luminance of the road surface region RR. This allows the illuminance estimation device 30 to estimate the illuminance ILL with high accuracy.

[0038] On the other hand, when the sky occupancy rate EOC is higher than the sky occupancy rate judgment value EOCth and the average luminance LAVRS of the road surface region RR is relatively low, it can be assumed that it is evening or night. In the evening or night, a large amount of light from a light source such as the sun is not incident on the road surface. Therefore, when the vehicle 10 is traveling in the evening or at night, it is assumed that the correlation between the luminance of the road surface region RR and the actual value of illuminance is relatively high. Therefore, when the sky occupancy rate EOC is higher than the sky occupancy rate judgment value EOCth and the average luminance LAVRS of the road surface region RR is equal to or lower than the road surface luminance judgment value LAVRSth, the illuminance estimation device 30 acquires the average luminance LAVRS of the road surface region RR as the illuminance ILL.

[0039] Therefore, the illuminance estimation device 30 can accurately estimate the illuminance ILL regardless of the time of day when the vehicle 10 is traveling. (3) When it is determined that the vehicle 10 is entering the interior of a structure, if it is determined that the sky occupancy rate EOC in the forward image IMG is relatively low, it can be inferred that the sky is not very visible in the forward image IMG. In this case, if the illuminance ILL is estimated using information about the sky area RE, the accuracy of the estimation may be low.

[0040] In this regard, when the sky occupancy rate EOC is equal to or less than the sky occupancy rate judgment value EOCth and the road surface occupancy rate ROC is higher than the road surface occupancy rate judgment value ROCth, the illuminance estimation device 30 calculates the illuminance ILL using the above relational expression (D1). This allows the illuminance estimation device 30 to estimate the illuminance ILL based on the rate of change in the average luminance LAVES of the road surface area RR from the point in time when the state in which at least one of the determinations in step S45 and step S61 is negative (NO) changes to a state in which both of the determinations are positive (YES). As a result, the illuminance estimation device 30 can estimate the illuminance ILL even when the sky occupancy rate EOC is relatively low.

[0041] (4) When it is determined that the vehicle 10 is entering a structure, if it is determined that both the sky occupancy ratio EOC and the road occupancy ratio ROC in the forward image IMG are relatively low, it can be inferred that both the correlation between the luminance and the actual illuminance value of the sky region RE and the correlation between the luminance and the actual illuminance value of the road region RR are low. Therefore, the illuminance estimation device 30 retains the illuminance ILL when the sky occupancy ratio EOC is equal to or less than the sky occupancy ratio judgment value EOCth and the road occupancy ratio ROC is equal to or less than the road occupancy ratio judgment value ROCth. This allows the illuminance estimation device 30 to prevent a decrease in the estimation accuracy of the illuminance ILL.

[0042] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0043] In the analysis process shown in FIG. 4, the second processing circuit 42 may set the entry flag FLG to ON even when the vehicle 10 has already entered the interior of the structure. If the empty space occupancy rate EOC is equal to or less than the empty space occupancy rate judgment value EOCth (S45: NO), the second processing circuit 42 may calculate the illuminance ILL by processing in step S63, regardless of whether the road surface occupancy rate ROC is higher than the road surface occupancy rate judgment value ROCth.

[0044] When the empty space occupancy rate EOC is equal to or less than the empty space occupancy rate judgment value EOCth (S45: NO), the second processing circuit 42 may maintain the illuminance ILL regardless of whether the road surface occupancy rate ROC is higher than the road surface occupancy rate judgment value ROCth.

[0045] If the sky occupancy rate EOC is higher than the sky occupancy rate judgment value EOCth (S45: YES), the second processing circuit 42 may acquire the average luminance LAVES of the sky area RE as the illuminance ILL regardless of whether the average luminance LAVRS of the road surface area RR is higher than the road surface luminance judgment value LAVRSth.

[0046] If the sky occupancy rate EOC is higher than the sky occupancy rate judgment value EOCth (S45: YES), the second processing circuit 42 may acquire the average luminance LAVRS of the road surface area RR as the illuminance ILL regardless of whether the average luminance LAVRS of the road surface area RR is higher than the road surface luminance judgment value LAVRSth.

[0047] 5, the second processing circuit 42 may acquire a value different from the average brightness LAVRS as the illuminance ILL, as long as the second processing circuit 42 can acquire a value corresponding to the brightness of the road surface area RR as the illuminance ILL. For example, the second processing circuit 42 may acquire the brightness of the divided area with the highest brightness in the road surface area RR as the illuminance ILL.

[0048] 5, the second processing circuit 42 may acquire a value different from the average brightness LAVES as the illuminance ILL, as long as the second processing circuit 42 can acquire a value corresponding to the brightness of the sky region RE as the illuminance ILL. For example, the second processing circuit 42 may acquire the brightness of the brightest divided region in the sky region RE as the illuminance ILL.

[0049] In the above embodiment, an example is described in which the illuminance ILL estimated by the illuminance estimation device 30 is used for controlling automatic turning on and off of lights. However, the illuminance ILL can be used for other controls in the vehicle 10. For example, the illuminance ILL may be used for dimming control of an in-vehicle display.

[0050] The second processing circuit 42 is not limited to a circuit having a CPU and ROM and executing software processing. In other words, the second processing circuit 42 may have any of the following configurations (a), (b), and (c):

[0051] (a) The second processing circuit 42 includes one or more processors that execute various processes according to a computer program. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to execute processes. Memory, i.e., computer-readable media, includes any available media that can be accessed by a general-purpose or special-purpose computer.

[0052] (b) The second processing circuit 42 includes one or more dedicated hardware circuits for executing various processes. Examples of the dedicated hardware circuits include application specific integrated circuits (ASIC) and FPGA. ASIC is an abbreviation for "Application Specific Integrated Circuit," and FPGA is an abbreviation for "Field Programmable Gate Array."

[0053] (c) The second processing circuit 42 includes a processor that executes some of the various processes in accordance with a computer program, and a dedicated hardware circuit that executes the remaining processes among the various processes.

[0054] The first processing circuit 32 may have any one of the above configurations (a), (b), and (c). The expression "at least one" used herein means "one or more" of the desired options. As an example, the expression "at least one" used herein means "only one option" or "both of two options" if the number of options is two. As another example, the expression "at least one" used herein means "only one option" or "any combination of two or more options" if the number of options is three or more. [Explanation of symbols]

[0055] 10...vehicle, 11...front camera, 30...illuminance estimation device, 31...image recognition device, 41...illuminance acquisition device

Claims

1. An illuminance estimation device that estimates illuminance, which is the brightness around a vehicle, comprising: acquiring a forward image that is an image in front of the vehicle; acquiring a luminance of a road surface area of ​​the forward image, the road surface on which the vehicle is traveling being captured; determining whether the vehicle is entering a structure accessible to the vehicle by analyzing the forward image; When it is determined that the vehicle will enter the interior of the structure, a value corresponding to the luminance of the road surface area is acquired as the illuminance. Illuminance estimation device.

2. acquiring an occupancy rate of a sky area, which is an area in the forward image where the sky is captured; obtaining a luminance of the sky region; When it is determined that the vehicle will not enter the interior of the structure, if both the occupancy rate of the sky area is higher than a sky occupancy rate determination value and the luminance of the road surface area is higher than a road surface luminance determination value, a value corresponding to the luminance of the sky area is acquired as the illuminance. The illumination estimation device according to claim 1 .

3. When it is determined that the vehicle will not enter the interior of the structure, if both of the following conditions are met: the occupancy rate of the sky area is higher than the sky occupancy rate determination value, and the luminance of the road surface area is equal to or lower than the road surface luminance determination value, a value corresponding to the luminance of the road surface area is acquired as the illuminance. The illumination estimation device according to claim 2 .

4. acquiring an occupancy rate of a sky area, which is an area in the forward image where the sky is captured; obtaining an occupancy rate of the road surface area in the forward image; When it is determined that the vehicle will not enter the interior of the structure, and both of the occupancy rate of the sky area being equal to or less than a sky area occupancy rate judgment value and the occupancy rate of the road surface area being higher than a road surface occupancy rate judgment value are established, calculate the illuminance so that the illuminance increases as the luminance of the current road surface area increases relative to the luminance of the road surface area at the time when both of the occupancy rate of the sky area being equal to or less than the sky area occupancy rate judgment value and the occupancy rate of the road surface area being higher than the road surface occupancy rate judgment value are established. The illumination estimation device according to claim 1 .

5. When it is determined that the vehicle will not enter the interior of the structure, if both of the occupancy rate of the sky area is equal to or less than the sky occupancy rate determination value and the occupancy rate of the road surface area is equal to or less than the road surface occupancy rate determination value, the illuminance is maintained. The illumination estimation device according to claim 4 .

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