JP2010283631A - Image sensing device and method for processing image in the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image sensing device which performs an AGC processing without being affected by a high brightness region due to the sun and an illumination or the like including an intense light source, even when this kind of the high brightness exists in an image, and obtains the image from a part near a camera to a long distance, and also to provide a method for processing the image in the image sensing device. <P>SOLUTION: The image sensing device is equipped with: the camera 11 including an image sensing element 13 including a plurality of pixels; and an image processing means conducting AGC processing to an image signal while using the brightness level of the image as a reference object for the AGC processing. The image processing means includes: an image divider dividing the image into two of an upper region and a lower region while using a horizon as a boundary; and a high brightness region detector detecting a continuous region as a high brightness region when there is the continuous region by the set of pixels corresponding to the image signal of an output voltage not less than a set voltage in the image. The image processing means further includes a high brightness region removing part removing the output voltage of the pixels in the detected high brightness region from the reference object for the AGC processing when the number of the pixels in the high brightness region is lower than or equal to a fixed number. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging device and an image processing method in the imaging device, and more particularly to an imaging device that performs AGC processing on an image signal output from an imaging device based on a luminance level of a pixel and an image processing method in the imaging device.

As a conventional technique related to an imaging apparatus, for example, there is an imaging apparatus disclosed in Patent Document 1.
The imaging device disclosed in Patent Document 1 includes evaluation value detection means for outputting the luminance signal level of each captured video signal in a sampling area divided on the screen as an exposure evaluation value for each area.
In addition, the imaging apparatus includes an arithmetic unit that calculates a sum of exposure evaluation values, and an exposure adjustment unit that controls an amplification factor of the captured video signal so that an output from the arithmetic unit matches a preset target value. It has.
According to this imaging apparatus, when the exposure evaluation value includes an exposure evaluation value that is larger than the reference range, the input of the corresponding exposure evaluation value to the calculation means is blocked.

As another conventional technique, for example, there is an imaging apparatus described in Patent Document 2.
The imaging apparatus disclosed in Patent Document 2 includes a luminance level detection unit, and the luminance level detection unit detects the luminance level of the imaging result for each region obtained by dividing one screen of the imaging result by the imaging element. .
The imaging apparatus includes a region detection unit, and the region detection unit determines a luminance level of each region and detects a region having a low luminance level.
Further, the imaging apparatus includes control means for performing exposure control so as to increase the brightness of the imaging result in accordance with the backlight intensity in the exposure control for backlight correction.
According to this imaging apparatus, a low luminance level region due to backlight is detected, an average value (average luminance level) of the low luminance level region is calculated, and the average luminance level of the low luminance level region and the low luminance level are calculated. The backlight intensity is calculated from the average luminance level of other areas excluding the area. Exposure control according to the backlight intensity is performed on the entire screen. When the backlight intensity is equal to or greater than a predetermined value, the increase in the brightness of the imaging result is stopped.

Furthermore, as another related art, for example, a backlight correction device disclosed in Patent Document 3 is known.
The backlight correction device of Patent Document 3 is a device that performs backlight correction using an imaging signal.
The backlight correction apparatus sequentially compares the luminance level of the imaging signal with a predetermined level to detect unnecessary high-luminance portions, memory means for storing position information of unnecessary portions, and based on the position information Correction means for attenuating the luminance level of the image pickup signal corresponding to the unnecessary portion.
According to the backlight correction device, an unnecessary high-luminance portion in the imaging screen is detected, and the luminance level is attenuated only in the unnecessary portion, so that a setting area for backlight determination is set for the unnecessary high-luminance portion in the imaging screen. It can be matched to any shape.

JP-A-1-180189 JP 2003-116049 A JP-A-7-23281

However, in the prior art of Patent Document 1, even if an object that needs to be appropriately exposed is included in the area including the abnormal luminance portion, the exposure of the area including the abnormal luminance portion is performed. Due to the prevention of the evaluation value, there is a problem that the exposure of the object is not adjusted.
Further, in the conventional technique of Patent Document 2, when the backlight intensity is equal to or greater than a predetermined value, the increase in the brightness of the imaging result is stopped. Therefore, when the backlight intensity is equal to or greater than the predetermined value, the high luminance level region is saturated. Although it does not, there is a problem that a region with a low luminance level becomes dark. In addition, when appropriate exposure control is performed for areas where the backlight intensity is greater than or equal to a predetermined value and the brightness level is low, control is performed according to the amount of backlight intensity, such as by performing exposure control after assigning weighting factors to areas with different brightness levels. Need.
Furthermore, in the conventional technique of Patent Document 3, the backlight signal is corrected by attenuating the luminance signal in the high-brightness region serving as the backlight part, and the backlight part can be removed, but this is merely a technique for correcting the backlight part. .

  The present invention has been made in view of the above-described problems, and the object of the present invention is influenced by this type of high-intensity region even if there is a high-intensity region in the image due to the sun or illumination with a strong light source. It is an object of the present invention to provide an imaging apparatus that can perform AGC processing and acquire images from the vicinity of the camera to a distance and an image processing method in the imaging apparatus.

  In order to solve the above-described problems, the present invention outputs a camera including an image sensor having a plurality of pixels, and a luminance level of an image obtained by the image sensor as a reference target for AGC processing. An image processing unit that performs AGC processing on an image signal, wherein the image processing unit divides the image obtained by the image sensor into an upper region and a lower region with a horizontal line as a boundary An image dividing unit that performs detection, a high-luminance region detection unit that detects the continuous region as a high-luminance region when a continuous region of pixels corresponding to an image signal having an output voltage equal to or higher than a set voltage exists in the upper region, and a detection And a high-brightness region excluding unit that excludes the output voltage of the pixel in the high-brightness region from the reference target for AGC processing when the number of pixels in the high-brightness region is equal to or less than a predetermined number. And wherein the Rukoto.

According to the present invention, an image picked up by a camera is obtained by an image pickup device, but the image is divided into an upper region and a lower region with a horizontal line as a boundary, and images from the vicinity of the camera to a distant place are obtained.
When a continuous region of pixels that output a voltage equal to or higher than a preset voltage value exists in the upper region, this continuous region is detected as a high luminance region with a high luminance level.
When the number of pixels in the detected high-brightness area is equal to or less than a predetermined number, this high-brightness area is a high-brightness area, for example, due to the sun or illumination with a strong light source, and is excluded from the reference target for AGC processing. .
In this case, the image processing means performs AGC processing on the image signal from the image pickup device, with the luminance level of the region excluding the high luminance region having a predetermined number of pixels or less as a reference target.
On the other hand, when the number of pixels in the detected high brightness area exceeds a predetermined number, the high brightness area in which the number of pixels exceeds the predetermined number is not excluded from the reference object of the AGC process.
As a result, even when a high-luminance region that should be excluded from the reference target for AGC processing is included in the image, AGC processing can be performed on the image signal using the luminance level of the region excluding the high-luminance region as the reference target.
For this reason, for example, images from the vicinity of the camera subjected to AGC processing to a distant place can be acquired without being affected by the high luminance region due to the sun or illumination with a strong light source.

  In the present invention, in the above imaging device, the camera may have an angle of view that is fixed at an installation destination with a predetermined depression angle and includes a range of 90 degrees or more in the vertical direction.

  In this case, the horizontal line is surely included in the image, and an image from the vicinity of the camera to a distant place can be acquired.

  In the present invention, in the above imaging apparatus, the installation destination of the camera may be a moving body.

  In this case, in a moving body such as a vehicle, for example, an image from the vicinity of the camera to a distant place that is not affected by a high luminance region due to the sun or illumination with a strong light source can be acquired when the moving body moves.

  In the present invention, in the above imaging device, the position of the boundary between the upper region and the lower region in the image may be fixed.

  In this case, since the position of the boundary between the upper region and the lower region in the image is fixed, it is not necessary to reset the boundary between the upper region and the lower region of the acquired image each time an image is captured.

  In the present invention, in the above-described imaging device, the imaging element may be a CMOS.

  In this case, since the image pickup device is a CMOS, smear that is likely to occur in a CCD does not appear, and an image without smear can be obtained by using a CMOS for the image pickup device.

  In addition, according to the present invention, AGC processing is performed on an image signal output from the imaging device, with a camera including an imaging device having a plurality of pixels and a luminance level of an image obtained by the imaging device as a reference target for AGC processing. An image processing unit that performs image processing, and the image processing unit includes an image dividing unit that divides the image obtained by the imaging element into an upper region and a lower region with a horizontal line as a boundary, The output voltage of the pixel in the lower region is used as a reference object for AGC processing.

According to the present invention, regardless of the presence or absence of a high luminance region having a high luminance level in the upper region, the luminance level in the lower region becomes a reference target for AGC processing, and AGC processing is performed on the image signal from the image sensor.
As a result, the AGC process is performed on the image signal from the image sensor regardless of the presence or absence of the high luminance region in the upper region, so that it is not necessary to detect the high luminance region, and the configuration of the imaging apparatus can be simplified.

  In addition, the present invention is an image processing method in an imaging apparatus that performs AGC processing on an image signal output from the imaging device, using the luminance level of an image obtained by the imaging device having a plurality of pixels as a reference target for AGC processing. The image obtained by the imaging device is divided into the upper region and the lower region with a horizontal line as a boundary, and a continuous region of pixels corresponding to an image signal having an output voltage equal to or higher than a set voltage is included in the image. When present, the continuous area is detected as a high-luminance area, and when the number of pixels of the detected high-luminance area is equal to or less than a predetermined number, the output voltage of the pixel in the high-luminance area is a reference target for AGC processing It is excluded from.

According to the present invention, even when a high-luminance region that should be excluded from the AGC processing reference object is included in the image due to the sun or illumination with a strong light source, the luminance level of the region excluding the high-luminance region is used as a reference. AGC processing can be performed on an image signal as a target.
Therefore, for example, an image from the vicinity of the camera subjected to AGC processing to a distant place can be acquired without being affected by a high luminance region caused by the sun or illumination with a strong light source.

  In addition, the present invention is an image processing method in an imaging apparatus that performs AGC processing on an image signal output from the imaging device, using the luminance level of an image obtained by the imaging device having a plurality of pixels as a reference target for AGC processing. The image obtained by the imaging device is divided into the upper region and the lower region with a horizontal line as a boundary, and the output voltage of the pixel in the lower region is used as a reference object for AGC processing. .

According to the present invention, regardless of the presence or absence of a high-brightness region with a high luminance level in the upper region, the AAGC processing uses the luminance level in the lower region as a reference target and performs AGC processing on the image signal from the image sensor.
As a result, the AGC process is performed on the image signal from the image sensor regardless of the presence or absence of the high luminance region in the upper region, so that it is not necessary to detect the high luminance region, and the configuration of the imaging apparatus can be simplified.

  According to the present invention, even if there is a high brightness area due to the sun or illumination with a strong light source in the image, AGC processing is performed without being affected by this type of high brightness area, and an image from the vicinity of the camera to a far place can be acquired. it can.

1 is a side view showing a vehicle equipped with an imaging device according to a first embodiment of the present invention. 1 is a block diagram illustrating a configuration of an imaging apparatus according to a first embodiment of the present invention. It is a flowchart of the camera calibration in an imaging device. It is a figure which shows the example of an image acquired by the imaging device which concerns on 1st Embodiment. It is a flowchart which shows the procedure of the image process in an imaging device. It is a figure which shows the example of an image containing the high-intensity area | region imaged with the camera. It is a flowchart which shows the procedure of the image process of the imaging device which concerns on 2nd Embodiment.

(First embodiment)
Hereinafter, an imaging device according to a first embodiment will be described with reference to the drawings.
The imaging device of 1st Embodiment is an example which is provided in the rear part of the motor vehicle as a moving body, and images the vehicle back.
As shown in FIG. 1, a camera 11 is mounted on the rear upper part of a vehicle M as an installation destination.
A display 14 that displays captured images is installed in the driver's seat of the vehicle.
The optical axis P of the camera is set to a depression angle α, and the camera 11 has an angle of view β including a range of 90 degrees or more in the vertical direction.

The camera 11 is a CMOS (complementary metal oxide semiconductor) camera.
As shown in FIG. 2, the camera 11 includes an optical element including a lens 12 and an image sensor 13 formed by a large number of pixels arranged in a lattice pattern.
An image captured by the camera 11 is formed on the pixels of the image sensor 13.
The camera 11 is connected to a controller 15 as image processing means, and a display 14 is connected to the controller 15.
The controller 15 is connected to the camera 11 and A / D converter 16 for A / D converting the image signal from the camera 11; a CPU (central processing unit) 17 for executing various data processing and programs; A random access memory (RAM) 18, a read only memory (ROM) 19 that is a nonvolatile memory, and a readable / writable flash memory 22.
Further, the controller 15 includes an AGC circuit 20 that performs AGC (Auto Gain Control) processing on the A / D converted image, and an output interface 21 that outputs the AGC processed image to the display 14. .

The RAM 18 has a cell coordinate storage unit that stores cell coordinates of each pixel in the image sensor 13 in addition to a function of storing and storing an image signal captured by the camera 11.
Further, the RAM 18 has a high-brightness-area cell coordinate storage unit that stores cell coordinates in a high-brightness area formed by a set of pixels corresponding to an image signal having an output voltage of a high-brightness level.
Further, the RAM 18 includes a high-brightness area number storage unit that stores area numbers assigned to a plurality of high-brightness areas when there are a plurality of high-brightness areas in the image.

The ROM 19 is a program for dividing an image obtained by the image pickup device 13 into an upper region and a lower region after correcting image distortion due to lens distortion (camera calibration) included in the camera 11. A program necessary for image processing is stored.
In addition, in order to perform camera calibration, the flash memory 22 stores a necessary amount of pixel movement for each address of the output image as a map.

The CPU 17 divides an image obtained by the image sensor 13 into an upper region and a lower region by executing a program stored in the ROM 19 or calculating data of the RAM 18.
Further, the CPU 17 has a function of calculating the luminance level for each pixel based on the measurement of the output voltage of the image signal output from each image sensor.
Further, the CPU 17 has a function of detecting a high luminance area in the image, and also has a function of excluding the high luminance area from the AGC processing reference target when the number of pixels in the high luminance area is equal to or less than a predetermined number.
Therefore, the CPU 17 corresponds to an image dividing unit, a high luminance region detecting unit, and a high luminance region excluding unit.

Next, the procedure of camera calibration of the imaging apparatus 10 according to this embodiment and the division of an image obtained by the imaging element 13 will be described.
FIG. 3 is a flowchart showing the camera calibration of the imaging apparatus 10 and the procedure of dividing the image obtained by the imaging device 13 into steps. In the flowchart shown in FIG. 3, steps S1 to S6 exist.
First, the camera 11 is installed in the vehicle (S1).
After the camera 11 is installed, the CPU 17 performs camera calibration by executing a calibration program stored in the ROM 19 (S2).
In camera calibration, a calibration board having a plurality of reference points is photographed by the camera 11, and the relative reference relationship between the actual reference point drawn on the image and the theoretical reference point of the camera 11 is matched. Correct.
In the correction of the relative positional relationship, camera parameters are acquired by arithmetic processing, and the acquired camera parameters are stored in the flash memory 22 (S3).
By storing the camera parameters in the flash memory 22, it is not necessary to perform camera calibration each time an image is acquired by the camera 11.
Lens distortion or the like is corrected in the image displayed on the display 14 by camera calibration.

FIG. 4 is an image captured and acquired by the camera 11 after camera calibration, and is a diagram illustrating a state in which the image is divided into an upper region S and a lower region G.
The image is formed by a plurality of pixels arranged in a grid of m columns and n rows.
The position of the pixel in the image is specified by each pixel having an address by cell coordinates (X, Y). In the image of FIG. 4, the pixel at the upper left corner is the origin of cell number 0, and the cell coordinate of the origin is (0 , 0).
Cell coordinates are set so that the cell number and the value of the X axis increase from the origin (0, 0) to the right, and the cell number and the value of the Y axis increase from the origin.
Therefore, the cell number of the pixel in the lower right corner that is the end point is the maximum (m + 1) (n + 1) −1, and the cell coordinates of the end point are (m, n).
The optical axis P of the camera 11 according to this embodiment is fixed to the rear portion of the vehicle M as the installation destination with a predetermined depression angle α, but has an angle of view β including a range of 90 degrees or more in the vertical direction. From the image taken by the camera 11, there is a horizontal line HL including the vanishing point VP.
The horizontal line HL including the vanishing point VP here is always included in an image captured by the camera 11 in an outdoor state without an obstacle.
Incidentally, the vanishing point is a point where parallel lines intersect in perspective.

The CPU 17 calculates a horizontal line HL including the vanishing point VP in the image after camera calibration by executing a program stored in the ROM 19, and the horizontal line HL in the image is specified by a pixel having a specific cell number ( S4).
Cell coordinates (0, h) to (m, h) of a pixel having a specific cell number constituting the horizontal line HL are stored in the flash memory 22 (S5).
The horizontal line HL including the vanishing point VP serves as a boundary that divides the image into an upper region S and a lower region G.
By dividing the image into two parts with the horizontal line HL as a boundary, the upper region S in the image is recognized as an empty region (sky region), and the lower region G is recognized as a ground region (ground region). An empty area is set (S6).
The cell coordinates of the pixel having the cell number corresponding to the stored horizontal line HL are held in the flash memory 22, and each time an image is acquired, the cell coordinates corresponding to the stored horizontal line HL are called, and the called cell coordinates are A horizontal line HL in the image is specified.
Once set, the upper region S and the lower region G are fixed and not changed unless the cell coordinates of a specific cell number constituting the horizontal line HL are reset.
The camera calibration and the calculation of the horizontal line HL are performed, for example, when the camera 11 is fixed before the vehicle M is shipped, and after the vehicle is shipped, for example, after the parameters obtained in the camera calibration are reset at the time of maintenance inspection, etc. Do.

Next, a procedure from image acquisition by the camera 11 to AGC processing will be described with reference to FIG.
In the flowchart shown in FIG. 5, there are steps S11 to S35.
First, when the vehicle is driven, an image is captured by the camera 11, an image is formed on the image sensor 13 of the camera 11, and an image is acquired (S11).
The camera 11 captures images every predetermined unit time, and forms and captures the captured images on the image sensor 13.
The image picked up by the camera 11 is imaged on the image pickup device 13, but as shown in FIG. 4, the image is divided into an upper region S and a lower region G with a horizontal line HL including the vanishing point VP as a boundary. Images from the vicinity of the camera 11 to the distance are acquired.
After obtaining the image, the counter indicating the cell number is initialized to 0, and the cell coordinate storage unit in the RAM 19 is cleared and initialized (S12, S13).

Next, it is determined whether or not the cell number is the maximum cell number (m + 1) (h + 1) -1 in the upper region S (S14), but the cell number is the maximum cell number (m + 1) ( If it is not h + 1) -1, the output voltage of the image signal corresponding to the pixel is measured, and it is determined whether the measured output voltage of the image signal is equal to or higher than the set voltage (S15).
When it is determined that the output voltage of the pixel is equal to or higher than the set voltage, the cell number is converted into a corresponding cell coordinate as a pixel having a high luminance level, and the cell coordinate is stored in the cell coordinate storage unit of the RAM 19 (S16, S17). .
When the cell coordinates are stored in the cell coordinate storage unit, the cell number is incremented (S18), and the process returns to step S14.
Then, the output voltage of the image signal of the cell number incremented in step S15 is measured.
On the other hand, if it is determined that the voltage of the image signal of the measured cell number is less than the set voltage, the cell number is incremented without storing the cell coordinates (S18), and the process returns to step S14.
Then, the output voltage of the image signal of the cell number incremented in step S15 is measured.
When the cell number becomes the maximum cell number in the upper region S due to the increment of the cell number, the loop related to steps S15 to S18 is exited (S14).

After exiting the loop related to steps S15 to S18, the high brightness area number counter is initialized to 0, and the high brightness area in-cell coordinate storage section in the RAM 19 is cleared and initialized (S19, S20).
Next, it is determined whether or not a pixel having an output voltage equal to or higher than the set voltage exists outside the high luminance region (S21).
If it is determined that a pixel having an output voltage equal to or higher than the set voltage exists outside the high luminance area, a new high luminance area number is assigned because a new high luminance area exists (S22).
The high brightness area is a continuous area of pixels corresponding to an image signal having an output voltage equal to or higher than the set voltage, and holds the high brightness area number and the cell coordinates of each pixel forming the high brightness area.
For each cell coordinate that forms the high luminance area, the surrounding cell coordinates are called in such a manner that the range is expanded outward (S23).
It is determined whether or not the output voltage of the called cell coordinates is equal to or higher than the set voltage (S24).
When the output voltage of the called cell coordinates is equal to or higher than the set voltage, the called cell coordinates are added to the cell coordinate storage unit in the high brightness area of the RAM 18 as cell coordinates forming the same high brightness area. Store (S25).

For example, as shown in FIG. 6, an image including a plurality of high brightness areas L1 and L2 may be obtained.
As a situation where a plurality of high brightness areas L1 and L2 appear, for example, the sun itself existing in the sky in the daytime and sunlight reflected on the windows of a structure such as a building are assumed.
Alternatively, there may be a plurality of street lamps that are turned on outdoors at night, or a plurality of mercury lamps indoors.
When an image including a plurality of high brightness areas L1 and L2 is obtained, the cell coordinates are called so as to spread around a specific cell coordinate (x, y) of the high brightness area L1, and the cell number exceeding the set voltage is called. Confirmation is made for all the pixels constituting the high-luminance region until the cell coordinates disappear.
When the cell number whose output voltage of the image signal is equal to or higher than the set voltage is not called, the high brightness area number is incremented (S26).
In the case of FIG. 6, the high luminance area L1 is the high luminance area number 0 and becomes the incremented high luminance area number 1, and the high luminance area number 1 corresponds to the high luminance area L2.
Returning to the step (S21) of determining whether an image signal having an output voltage equal to or higher than the set voltage exists outside the high luminance area, an image having an output voltage equal to or higher than the set voltage outside the high luminance area corresponding to the incremented high luminance area number. When there is no signal, the process exits the loop related to steps S22 to S26.

After exiting the loop related to steps S22 to S26, the process proceeds to step S27, where the number of high luminance areas is held.
For example, in the case of FIG. 6, since the high luminance areas L1 and L2 exist, the high luminance area number 2 is held.
Next, the high brightness area number counter is initialized to 0 (S28).
Then, the high brightness area number is compared with the number of high brightness areas, and it is determined whether the high brightness area number is equal to or greater than the number of high brightness areas (S29).
If the high luminance area number is not greater than or equal to the number of high luminance areas, the maximum number of continuous pixels is calculated based on the cell coordinates that form the high luminance area (S30).

  A specific method for calculating the maximum number of continuous pixels in the high luminance region is to obtain the maximum Euclidean distance between two pixels in the high luminance region, and an integer approximated to this Euclidean distance is set as the “maximum continuous pixel number”.

When the maximum number of continuous pixels is obtained, it is determined whether or not the maximum number of continuous pixels is equal to or less than a predetermined number of pixels (S31).
When the maximum number of continuous pixels is equal to or less than the predetermined number of pixels, the output voltage of the image signal in the high luminance area corresponding to the high luminance area number at this time is excluded from the reference object of the AGC process (S32).
That is, if the maximum number of continuous pixels is equal to or smaller than the predetermined number of pixels in step S31, this high luminance area is recognized as a high luminance area that is not a reference target for AGC processing.
Specific examples recognized as a high-luminance region that is not a reference target for AGC processing include, for example, the sun and illumination with a strong light source.
When the output voltage of the image signal of the high luminance area corresponding to the high luminance area number is excluded from the reference object of the AGC process, the high luminance area number is incremented (S33).

On the other hand, when the maximum number of continuous pixels is not less than the predetermined number of pixels, the output voltage of the image signal of the high luminance area corresponding to the high luminance area number at this time is not excluded from the reference object of the AGC processing, and the high luminance area number Increment is performed (S31, S33).
If the maximum number of continuous pixels is not less than or equal to the predetermined number of pixels in step S31, the high luminance area is not recognized as a high luminance area that is not a reference object for AGC processing, and is set as a reference object for AGC processing.
An example of the high luminance region where the maximum number of continuous pixels is not less than the predetermined number of pixels is a bright sky where the sun is not reflected in fine weather.
After the high luminance area number is incremented, the high luminance area number is compared with the number of high luminance areas in step S29.
If the high brightness area number is not equal to or greater than the number of high brightness areas, the maximum number of continuous pixels in step S30 is calculated, and it is determined whether the maximum number of continuous pixels in step S31 is equal to or less than a predetermined number of pixels.
Although the predetermined number of pixels is set in advance, it may be set empirically based on the maximum number of continuous pixels in the high luminance region based on the sun imaged in advance or illumination with a strong light source.
Moreover, it is preferable that the predetermined number of pixels is changed according to the situation, for example, the predetermined number of pixels is changed according to the luminance and time.

If the high luminance area number and the number of high luminance areas are equal to or greater than, the process goes out of the loop related to steps S30 to S33, proceeds to step S34, and performs AGC processing on the image signal (S34).
In the AGC processing for the image signal, the upper region S and the lower region excluding the called high luminance region are excluded by excluding the voltage of the image signal from the pixels forming the high luminance region whose maximum continuous pixel number is equal to or less than the predetermined number of pixels. AGC processing is performed using the voltage of the image signal of the pixel in G as a reference target for AGC processing.
If there is no high luminance region to be excluded from the reference target for the AGC process in step S32, the AGC process is performed using the voltage of the image signal from the entire image sensor as the reference target for the AGC process.
The AGC process is performed based on the average value of the luminance levels of the region that is the reference target for the AGC process in the image.
After AGC processing, it is determined whether or not to continue image acquisition. If image acquisition is to be continued, the process returns to step S11. If image acquisition is not to be continued, the image processing is terminated (S35).

In this embodiment, by calculating the Euclidean distance of the high luminance area, the maximum number of continuous pixels in the high luminance area is obtained, and when the maximum continuous pixel number is equal to or less than the predetermined number of pixels, the high luminance area is processed by AGC processing. I was excluded from the standard object.
For example, when the number of pixels in the high luminance area is equal to or less than a predetermined number, a process of excluding the high luminance area from the reference object of the AGC processing can be considered. In this case, the sun, illumination with a strong light source, or the like A linear high-intensity area that has the same number of pixels as the high-intensity area having an area shape that approximates the circular shape by the line and that has pixels with an output voltage that is equal to or higher than the set voltage is continuously formed in one direction. The possibility to be excluded from remains.
In the process of obtaining the maximum number of continuous pixels in the high-brightness area based on the Euclidean distance and excluding the high-brightness area from the reference object of the AGC process when the maximum number of continuous pixels is equal to or less than the predetermined number of pixels, Compared with the case of discrimination based on the number of pixels in the area, it is easier to discriminate a high brightness area due to the sun or illumination with a strong light source as a high brightness area to be excluded from the reference object of AGC processing, while continuing in one direction. Thus, it is easy to discriminate the high-brightness area formed in a straight line so as not to be excluded from the reference object of the AGC process.

This embodiment has the following effects.
(1) When a continuous region of pixels that output a voltage equal to or higher than a preset voltage value exists in the image, the controller 15 detects this continuous region as a high luminance region with a high luminance level. When the maximum number of continuous pixels in the high luminance area is equal to or smaller than the predetermined number of pixels, the controller 15 excludes the high luminance area from the reference object of the AGC processing, and the controller 15 sets the luminance level of the area excluding the high luminance area as a reference. AGC processing is performed on the image signal from the image sensor 13 as a target. As a result, even if the image includes a high-luminance region that should be excluded from the reference target for AGC processing due to the sun, illumination with a strong light source, etc., the luminance level of the region excluding the high-luminance region is used as the reference target. AGC processing can be performed on the signal. Therefore, it is possible to acquire an image from the vicinity of the camera 11 subjected to AGC processing to a distant place without being influenced by the sun, illumination having a strong light source, or the like.

(2) Since the optical axis P of the camera 11 is fixed to the vehicle M with a predetermined depression angle α and has an angle of view β including a range of 90 degrees or more in the vertical direction, the vanishing point VP The horizontal line HL including is surely included in the image, and an image from the vicinity of the camera 11 to a distant place can be acquired.
(3) Since the installation destination of the imaging device 10 is the vehicle M that is a moving body, in the vehicle M, it is possible to acquire images from the vicinity of the camera 11 that are not affected by the high-luminance region to a distance when the vehicle M moves. It is.
(4) Since the boundary divided into the upper region S and the lower region G in the subsequent image is fixed by the calibration after the camera 11 is installed, the image obtained by the image sensor 13 every time the image is acquired There is no need to divide the upper region S and the lower region G in FIG.
(5) Since the image pickup device 13 is a CMOS, smear that is likely to occur in a CCD does not appear, and an image without smear can be obtained by using a CMOS for the image pickup device 13.
(6) Since the high luminance area is determined only from the upper area S of the horizontal line HL, and the AGC process is performed on the entire image excluding the high luminance area as a reference object, it is possible to obtain a good image with simpler processing than before. .

(Second Embodiment)
Next, a second embodiment will be described.
Since the imaging apparatus according to the second embodiment is basically the same as the imaging apparatus according to the first embodiment, the description of the first embodiment is used for common elements, and the reference numerals of the imaging apparatus are Used in common.

In the image processing in the imaging apparatus according to the first embodiment, when the upper region exists in the high luminance region, it is determined whether or not the high luminance region is excluded from the AGC processing reference target, and the sun or a strong light source is provided. In the case where the illumination forms a high luminance region, this type of high luminance region is excluded from the reference object and AGC processing is performed.
On the other hand, in the image processing in the imaging apparatus according to the second embodiment, the lower region G shown in FIG. 4 is always set as a reference target for AGC processing regardless of the presence or absence of the high luminance region in the upper region.
That is, the AGC process is performed by excluding the upper area S, which is an empty area, from the reference target for the AGC process.

The procedure for camera calibration and setting of the horizontal line HL is based on the flowchart shown in FIG. 3 as in the first embodiment.
A procedure from image acquisition to AGC processing by the imaging apparatus according to this embodiment is shown by a flowchart in FIG.
In the flowchart shown in FIG. 7, there are steps S41 to S43, but an image is acquired (S41) and AGC processing is performed (S42).
The lower area G is always a reference object for AGC processing, and the upper area S, which is an empty area, is always excluded from the reference object for AGC processing.
It is determined whether or not to continue image acquisition after the AGC process (S43).
If it is determined that the image acquisition is to be continued, the process returns to step S41 to acquire the image. If it is determined that the image acquisition is not continued, the process is terminated.

In this embodiment, regardless of the presence or absence of a high-luminance region with a high luminance level in the upper region S, the lower region G is always set as a reference target for AGC processing and the upper region S that is an empty region is always AGC in the AGC processing. Excluded from standard processing criteria.
As a result, the AGC process is performed on the image signal from the image sensor 13 regardless of the presence or absence of the high brightness area in the upper area S, so that it is not necessary to detect the high brightness area, and the configuration of the imaging apparatus can be simplified.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the gist of the invention.
In the above embodiment, the camera is installed in the vehicle as the moving body. However, the installation destination of the camera is not limited to the moving body, and may be provided in a building or a ground structure.
○ In the above embodiment, after camera calibration, the upper and lower regions of the image are divided into two parts with the horizontal line including the vanishing point as the boundary, and the position of the boundary between the upper and lower regions in the image is fixed. Although set, for example, the position of the horizontal line including the vanishing point may be calculated every time an image is acquired. In this case, each time an image is acquired, the position of the boundary between the upper region and the lower region is set. Therefore, even when the vehicle moves on a sloped road surface, the screen is dynamically divided according to the slope of the road surface. It is possible to obtain a more appropriate image.
In the above embodiment, in the state where the camera is installed at the installation destination, it has an angle of view including a range exceeding 90 degrees in the vertical direction, but the camera may be, for example, a fisheye lens.

DESCRIPTION OF SYMBOLS 10 Imaging device 11 Camera 12 Lens 13 Image pick-up element 14 Display 15 Controller (as image processing means)
16 A / D converter 17 CPU
18 RAM
19 ROM
20 AGC circuit 21 Output interface 22 Flash memory M Vehicle P Optical axis S Upper region (empty region)
G Lower area (ground area)
HL Horizontal line VP Vanishing point L1, L2 High brightness area

Claims (8)

A camera including an imaging device having a plurality of pixels;
An image processing apparatus comprising: image processing means for performing AGC processing on an image signal output from the imaging device, with the luminance level of the image obtained by the imaging device as a reference target for AGC processing,
The image processing means includes
An image dividing unit that divides the image obtained by the image sensor into an upper region and a lower region with a horizontal line as a boundary;
A high-luminance area detector that detects the continuous area as a high-luminance area when a continuous area of pixels corresponding to an image signal having an output voltage equal to or higher than a set voltage exists in the upper area;
A high-intensity region excluding unit that excludes the output voltage of the pixels in the high-intensity region from a reference target for AGC processing when the number of detected pixels in the high-intensity region is a predetermined number or less. An imaging device.   The imaging apparatus according to claim 1, wherein the camera is fixed at an installation destination with a predetermined depression angle and has an angle of view including a range of 90 degrees or more in the vertical direction.   The imaging apparatus according to claim 1, wherein the installation destination of the camera is a moving body.   The imaging apparatus according to claim 1, wherein a position of a boundary between the upper region and the lower region in the image is fixed.   The imaging device according to claim 1, wherein the imaging device is a CMOS. A camera including an imaging device having a plurality of pixels;
An image processing apparatus comprising: image processing means for performing AGC processing on an image signal output from the imaging device, with the luminance level of the image obtained by the imaging device as a reference target for AGC processing,
The image processing means includes
An image dividing unit that divides the image obtained by the image sensor into an upper region and a lower region with a horizontal line as a boundary;
An image pickup apparatus, wherein an output voltage of a pixel in the lower region is set as a reference object for AGC processing. An image processing method in an imaging apparatus that performs AGC processing on an image signal output from the imaging device, with a luminance level of an image obtained by an imaging device having a plurality of pixels as a reference target of AGC processing,
The image obtained by the imaging device is divided into the upper region and the lower region with a horizontal line as a boundary,
When a continuous region of pixels corresponding to an image signal having an output voltage equal to or higher than a set voltage exists in the image, the continuous region is detected as a high luminance region,
An image processing method in an imaging apparatus, wherein when the number of detected pixels in the high luminance area is equal to or less than a predetermined number, the output voltage of the pixels in the high luminance area is excluded from a reference target for AGC processing. An image processing method in an imaging apparatus that performs AGC processing on an image signal output from the imaging device, with a luminance level of an image obtained by an imaging device having a plurality of pixels as a reference target of AGC processing,
The image obtained by the imaging device is divided into the upper region and the lower region with a horizontal line as a boundary,
An image processing method in an imaging apparatus, wherein an output voltage of a pixel in the lower region is used as a reference target for AGC processing.