JP2008035365A - Far-infrared imaging system and far-infrared imaging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a far-infrared imaging system and far-infrared image method for correcting output values of a plurality of far-infrared imaging devices so as to make the output values almost coincide with one another with respect to one and the same object. <P>SOLUTION: The far-infrared imaging system is provided with a plurality of far-infrared imaging apparatuses having imaging elements disposed in a matrix shape to pick up images around a vehicle and an arithmetic unit and corrects the output value in each imaging element on the basis of measured temperature of a road surface and outputs the output value. The arithmetic unit specifies a measuring point located almost at the center of an image in each image data acquired from the plurality of infrared imaging apparatuses and estimates a distance to the specified measuring point. Time required until the vehicle travels over the specified measuring point is calculated on the estimated distance and a vehicle speed, and the temperature of the road surface is acquired when the time required elapses after the image data is acquired. A correction factor is calculated for each imaging element on the basis of temperatures of the road surface at a plurality of points of time and output values of measuring points, and a far-infrared imaging device corrects the output value by the calculated correction factor and outputs the corrected output value to the outside. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a far-infrared imaging system and a far-infrared imaging method capable of correcting output luminance values of a plurality of far-infrared imaging devices that image the outside so as to output substantially the same luminance value for the same temperature.

  In order to ensure the safety of vehicles such as automobiles during night driving, many obstacle detection systems that detect the presence of obstacles such as pedestrians and bicycles using far-infrared imaging devices such as night vision have been developed. Usually, two far-infrared imaging devices are installed at a predetermined position in front of the vehicle, the distance to the obstacle detected by stereo vision is calculated, and the presence of the obstacle is detected by feature amount detection.

  However, a bolometer or the like often used as an imaging element of a far-infrared imaging device has a large variation in temperature detection sensitivity. Therefore, offset drift or the like based on time changes is likely to occur, so that noise is easily superimposed on the captured image, and it is difficult to improve obstacle detection accuracy.

In order to solve such a problem, for example, Non-Patent Document 1 discloses NUC (Non-Uniformity Correction), which is a representative example of a method of correcting sensitivity non-uniformity that is different for each image sensor. In Non-Patent Document 1, on the premise that the response characteristic of an image sensor is linear, an offset correction value for correcting an output value for a predetermined temperature for each image sensor, and an output value for a predetermined temperature change rate for each image sensor The gain correction value for correcting the difference is calculated, and the output value from the far-infrared imaging device is corrected.
“Real-time implementation of two-point non-uniformity correction for IR-CCD imagery”, SPIE Proc., Vol. 2598, p. 44-50, 1995

  However, in the above-described correction method of the output value of the imaging device, the offset correction value is not calculated corresponding to the absolute temperature. Therefore, when using a plurality of far infrared imaging devices, different far infrared imaging devices are the same. Even when the luminance value is output, it is not guaranteed that the detected temperatures are the same. Therefore, when extracting the feature amount of an image to detect whether it is an obstacle, the brightness, contrast, etc. of the image captured for each far-infrared imaging device are different, and the AGC (Auto Even if the (Gain Control) function is used, there is a problem that it may be difficult to accurately detect an obstacle.

  In particular, when performing distance measurement based on stereo vision based on images captured by far-infrared imaging devices installed on the left and right of the front of the vehicle, it is difficult to match the brightness and contrast of the images. It becomes difficult to improve accuracy. Therefore, by correcting the output luminance value so that the brightness, contrast, and the like of the images captured by both the imaging devices are substantially the same, the obstacle detection accuracy is dramatically improved.

  The present invention has been made in view of such circumstances, and a far-infrared imaging system capable of correcting the output values of a plurality of far-infrared imaging devices so as to substantially match the same object, and An object is to provide a far-infrared imaging method.

  In order to achieve the above object, a far-infrared imaging system according to a first aspect of the present invention includes a plurality of far-infrared imaging devices that have imaging elements arranged in a matrix and that capture an image around a vehicle, and a road surface below the vehicle A road surface temperature measuring means for measuring the temperature of the vehicle, and an arithmetic device connected to the far infrared imaging device and the road surface temperature measuring means so as to be able to communicate data, and outputs each image sensor based on the measured temperature of the road surface. A far-infrared imaging system that corrects and outputs a value includes speed detection means for detecting the speed of the vehicle, and the arithmetic unit displays each image data acquired from a plurality of far-infrared imaging devices at a predetermined position of the image. Based on the estimated distance and the speed of the vehicle, the specified measurement point is moved to the lower part of the vehicle based on the means for identifying the measured measurement point, the means for estimating the distance to the specified measurement point, and the vehicle speed. If it is determined that the time required to calculate, the time measuring means for starting time measurement from the time of image data acquisition, the means for determining whether the calculated required time has passed, Means for obtaining the temperature of the road surface measured by the road surface temperature measuring means, means for calculating a correction coefficient for each image sensor based on the temperature of the road surface at a plurality of time points and the output value of the measurement point, and the calculated correction coefficient The far-infrared imaging device comprises: means for receiving the calculated correction coefficient; and means for correcting the output value with the received correction coefficient and outputting it to the outside. To do.

  The far-infrared imaging system according to the second invention is the first invention, wherein the far-infrared imaging device linearly approximates the road surface temperature acquired at a plurality of points in time and the output value of the imaging device with respect to the measurement point. The output value with respect to the temperature is corrected.

  In the far-infrared imaging system according to a third aspect of the present invention, in the first or second aspect, the far-infrared imaging device includes a means for calculating a difference in road surface temperature obtained at a plurality of times, and the calculated difference is predetermined. A means for determining whether or not the value is smaller than the value and an output value with respect to the temperature are not corrected when the value is determined to be smaller by the means.

  A far-infrared imaging method according to a fourth aspect of the present invention includes a plurality of far-infrared imaging devices that have imaging elements arranged in a matrix and that capture an image around the vehicle, and measure the temperature of the road surface below the vehicle. Using the road surface temperature measuring means and the far infrared imaging device and the arithmetic device connected to the road surface temperature measuring means so as to be able to perform data communication, the output value is corrected for each image sensor based on the measured road surface temperature. In the far-infrared imaging method to be output, the calculation device specifies a measurement point displayed at a predetermined position of the image for each image data acquired from a plurality of far-infrared imaging devices, and the distance to the specified measurement point Based on the estimated distance and vehicle speed, calculate the time required for the specified measurement point to move to the lower part of the vehicle, start counting from the time of image data acquisition, and calculate the required time If it is determined whether or not it has elapsed, the temperature of the road surface measured by the road surface temperature measuring unit is acquired, and based on the road surface temperature at a plurality of time points and the output value of the measurement point The correction coefficient for each image sensor is calculated, the calculated correction coefficient is transmitted, and the far-infrared imaging device receives the calculated correction coefficient, corrects the output value with the received correction coefficient, and outputs the correction value to the outside It is characterized by doing.

  In the first invention and the fourth invention, a plurality of far-infrared imaging devices that have imaging elements arranged in a matrix and that take an image around the vehicle, and a road surface temperature measurement that measures the temperature of the road surface below the vehicle The output value is corrected for each image sensor based on the measured temperature of the road surface using the means and a computing device connected to the far-infrared imaging device and the road surface temperature measuring means so as to be able to perform data communication. The calculation device specifies a measurement point displayed at a predetermined position of the image for each image data acquired from a plurality of far-infrared imaging devices, and estimates the distance to the specified measurement point. Based on the estimated distance and the speed of the vehicle, a time required until the specified measurement point moves to the lower part of the vehicle is calculated. The road surface temperature is acquired when the required time has elapsed since the image data acquisition, and the correction coefficient for each image sensor is calculated based on the road surface temperature and the output values of the measurement points at a plurality of time points. The far-infrared imaging device acquires the correction coefficient calculated by the arithmetic device, corrects the output value with the correction coefficient, and outputs the correction value to the outside. Since the measurement points of images taken at different time points are different and the road surface temperature and output value are different, the temperature of the road surface measured at a plurality of time points and the output of the image sensor with respect to the temperature of the road surface By correcting the output value for each far-infrared imaging device using the value as a reference, the output value with respect to the measured road surface temperature can be substantially matched even when the far-infrared imaging device is different. Therefore, the brightness, contrast, and the like of images captured by a plurality of far-infrared imaging devices can be substantially matched, and the obstacle detection accuracy can be improved.

  In the second invention, the far-infrared imaging device corrects the output value with respect to the temperature by linearly approximating the temperature of the road surface acquired at a plurality of times and the output value of the imaging device with respect to the measurement point. Since the measurement points of images taken at different time points are different and the road surface temperature and output value are different, the temperature of the road surface measured at a plurality of time points and the output of the image sensor with respect to the temperature of the road surface By linearly approximating the value, the output value can be corrected for each far-infrared imaging device based on at least two road surface temperatures and output values.

  In the third invention, the far-infrared imaging device calculates a difference in temperature of the road surface acquired at a plurality of time points, and does not correct the output value with respect to the temperature when the calculated difference is smaller than a predetermined value. When the temperature difference is excessively small, the error due to the first-order approximation becomes excessive. Therefore, when the temperature difference is excessively small, the stored offset correction value and gain correction value are not updated. It is possible to maintain high output accuracy of the infrared imaging device.

  According to the present invention, the output value is corrected using the road surface temperature acquired at a plurality of points in time and the output value of the image sensor with respect to the measurement point, and output to the outside. Since the measurement points of images taken at different time points are different and the road surface temperature and output value are different, the temperature of the road surface measured at a plurality of time points and the output of the image sensor with respect to the temperature of the road surface By correcting the output value for each far-infrared imaging device using the value as a reference, the output value with respect to the measured road surface temperature can be substantially matched even when the far-infrared imaging device is different. Therefore, the brightness, contrast, and the like of images captured by a plurality of far-infrared imaging devices can be substantially matched, and the obstacle detection accuracy can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram schematically showing a configuration of a far-infrared imaging system according to an embodiment of the present invention. In the present embodiment, a set of far-infrared imaging devices 1 and 1 that capture surrounding images while traveling are mounted in the front grille near the center in front of the vehicle (also possible in a bumper). The far-infrared imaging devices 1 and 1 are imaging devices using infrared light having a wavelength of 7 to 14 micrometers.

  In FIG. 1, far-infrared imaging devices 1 and 1 are juxtaposed in a substantially symmetrical position in the left-right direction within a front grill of a vehicle. Image data captured by the far-infrared imaging devices 1 and 1 is transmitted to an arithmetic device 3 connected via a video cable 7 corresponding to an analog video system such as NTSC or a digital video system.

  The arithmetic device 3 executes various arithmetic processes using the acquired far infrared image data. The arithmetic device 3 is connected to the far infrared imaging devices 1 and 1 and the display device 4 having an operation unit via a cable 8 corresponding to a video system such as NTSC, VGA, DVI, etc. An output device such as an alarm device 5 that emits an audible warning by a sound effect or the like is connected via an in-vehicle LAN cable 6 compliant with CAN.

  The computing device 3 is also connected to a vehicle speed sensor (speed detection means) 2 for detecting the speed of the vehicle and a road surface temperature sensor (road surface temperature measurement means) 9 via an in-vehicle LAN cable 6 compliant with CAN. The speed of the vehicle and the temperature of the road surface can be acquired.

  FIG. 2 is a block diagram showing the configuration of the far-infrared imaging device 1 according to the embodiment of the present invention. In FIG. 2, the image capturing unit 11 includes an image sensor that converts an optical signal into an electrical signal in a matrix. As the far-infrared imaging device, an infrared sensor such as a vanadium oxide bolometer using a micromachining technique or a pyroelectric type using a BSTO (Barium-Titanium Oxide) is used.

  The image capturing unit 11 reads an infrared light image around the vehicle as a luminance signal, and transmits the read luminance signal to the signal processing unit 12 that is an LSI substrate. FIG. 3 is a block diagram showing a configuration of the signal processing unit 12 of the far-infrared imaging device 1 according to the embodiment of the present invention. The signal processing unit 12 includes an A / D conversion unit 121, a NUC (Non-Uniformity Correction) processing unit 122, a BPR (Bad-Pixel Replacement) processing unit 123, a non-volatile memory such as a flash memory, and a temporary storage such as an SRAM. It is composed of a RAM (storage means) 125 that is a memory.

  The signal processing unit 12 converts the luminance signal received from the image capturing unit 11 into a digital signal by the A / D conversion unit 121, and outputs the luminance signal output for each image sensor by the NUC (Non-Uniformity Correction) processing unit 122. to correct.

The NUC processing unit 122 outputs, as a correction coefficient by calibration, an offset correction value for correcting a luminance value output for a predetermined temperature for each image sensor and a predetermined temperature change rate for each image sensor. A gain correction value for correcting a difference in brightness value is calculated to correct the brightness signal. For example, when the luminance value for each imaging element arranged in a matrix of i rows and j columns is V _ij , the NUC processing unit 122 performs the calculation shown in (Equation 1) to obtain the luminance value for each imaging element as V ′. Correct to _ij .

In (Equation 1), G _ij represents a gain correction value, and O _ij represents an offset correction value. For example, the luminance for each image sensor when an object having a uniform temperature distribution such as a black body furnace or a shutter is imaged. It is a value calculated based on the value.

Further, the BPR processing unit 123, the corrected luminance value for each image pickup element 'perform defective pixel correction to _ij, V the luminance value for each image pickup element' V correction in the correction luminance value V _"ij a _ij To do.

  In the plurality of far-infrared imaging devices 1 and 1, in order to correct the output value so that the same luminance value is output when the temperature of the imaging object is the same, the object having a substantially uniform temperature distribution is used. It is necessary to obtain an absolute temperature and calculate a temperature correction coefficient so that the luminance values output corresponding to the absolute temperature are substantially the same. Therefore, in the present embodiment, a plurality of far-infrared rays are obtained by obtaining a plurality of output luminance values of measurement points on the road surface imaged at a plurality of time points and a road surface temperature at the measurement points and approximating to a linear function. The output luminance values for the same temperature in the imaging devices 1 and 1 are substantially matched.

  In the present embodiment, a non-contact type road surface temperature sensor (road surface temperature measuring means) 9 such as a known infrared sensor is used as means for detecting the road surface temperature. The road surface temperature sensor 9 is installed in the vicinity of the center of the lower part of the vehicle, and measures the temperature of the road surface by irradiating near infrared rays since the distance to the road surface is relatively short.

The signal processing unit 12 receives the temperature correction coefficient calculated by the calculation device 3 based on the time required for the measurement point corresponding to the road surface portion ahead of the vehicle to reach the lower part of the vehicle, and the BPR processing unit 123. The luminance value obtained by correcting the defective pixel in step V ′ _ij is corrected to the corrected luminance value V ″ _ij .

  The communication interface unit 14 is an LSI substrate, and sends image data stored in the image memory 13 to an external device and takes a captured image in accordance with a command received from the external device via the communication line 2 such as a communication cable. The conversion of the transfer rate according to the resolution of the data, the format conversion of the data for transmitting the image data, and the like are performed.

  FIG. 4 is a block diagram showing a configuration of the arithmetic device 3 of the far infrared imaging system according to the embodiment of the present invention. The arithmetic device 3 is an image processing ECU, and includes at least an imaging device interface unit 31a, a video output unit 31b, a communication interface unit 31c, an image memory 32, and an LSI 33 incorporating a RAM 331.

  The imaging device interface unit 31 a inputs video signals from the far-infrared imaging devices 1 and 1 and outputs the offset correction value and gain correction value calculated by the arithmetic device 3. The imaging device interface unit 31a stores the image data input from the far-infrared imaging devices 1 and 1 in the image memory 32 in synchronization with one frame unit. The video output unit 31 b outputs image data to the display device 4 such as a liquid crystal display via the video cable 8.

  The communication interface unit 31 c transmits an output signal such as a synthesized sound to the alarm device 5 such as a buzzer or a speaker via the in-vehicle LAN cable 6. Further, the communication interface unit 31 c receives the vehicle speed from the vehicle speed sensor 2 and the road surface temperature from the road surface temperature sensor 9 via the in-vehicle LAN cable 6, and stores them in the RAM 331.

  The image memory 32 is an SRAM, flash memory, SDRAM or the like, and stores image data input from the far-infrared imaging devices 1 and 1 via the imaging device interface unit 31a.

  5 and 6 are flowcharts showing a processing procedure of the LSI 33 of the arithmetic unit 3 of the far-infrared imaging system according to the embodiment of the present invention. The LSI 33 that performs image processing reads the image data stored in the image memory 32 in units of frames (step S501), and starts measuring time with a built-in timer or the like (step S502). The LSI 33 specifies measurement points where the surrounding luminance values are substantially uniform (step S503). In the present embodiment, as a measurement point, a point belonging to a region having a substantially uniform luminance value in the lower vicinity of the center of the image is specified as the measurement point. That is, a measurement point is acquired as a representative point on the road surface. The method for specifying the measurement point is not particularly limited, and any method may be used as long as one point on the road surface can be specified.

  The LSI 33 estimates the position coordinates in the coordinate system with the vehicle front end of the measurement point as the origin based on the parallax of the images captured by the left and right far-infrared imaging devices 1 and 1 at the specified measurement point (step S504). . The LSI 33 acquires the speed of the vehicle from the speed sensor 2 (step S505), and calculates the time required for the measurement point estimated from the position coordinates to reach the lower part of the vehicle due to the movement of the vehicle (step S506). FIG. 7 is a diagram illustrating an example of an image captured by the far-infrared imaging device 1, and FIG. 8 is a diagram schematically illustrating a concept of a required time calculation method. In the example of FIG. 7, the road surface is photographed in the vicinity of the center of the image, that is, in the traveling direction of the vehicle. Accordingly, the surrounding luminance values are substantially uniform, and the measurement point P1 is specified at the lower center of the image.

  The position coordinates of the measurement point P1 can be estimated by stereo viewing of images captured by the left and right far-infrared imaging devices 1 and 1. That is, the distance L from the vehicle front end to the measurement point P1 shown in FIG. 8 can be easily estimated. Further, since the mounting position P2 of the road surface temperature sensor 9 for measuring the road surface temperature is self-evident, the distance l from the front end of the vehicle to the mounting position P2 of the road surface temperature sensor 9 can also be acquired. Therefore, the required time ΔT for the measurement point P1 to move to below the road surface temperature sensor 9 can be obtained by (L + 1) / V, where V is the vehicle speed detected by the speed sensor 2.

  The LSI 33 determines whether or not the calculated required time ΔT has elapsed (step S507), and if the LSI 33 determines that the required time ΔT has elapsed (step S507: YES), the LSI 33 is the road surface temperature sensor 9. The measured road surface temperature is acquired (step S508) and stored in the RAM 331 in association with the output luminance value of the measurement point (step S509).

The LSI 33 determines whether or not the latest road surface temperature and output luminance value are already stored in the RAM 331 (step S510), and if the LSI 33 determines that they are stored (step S510: YES), the LSI 33 Reads out the temperature and output luminance values of the two sets of road surfaces from the RAM 331, calculates a linear function when linear interpolation is performed (step S511), and causes the BPR processing unit 123 so that the output luminance value follows the linear function. The luminance value of each image sensor that has corrected the defective pixel is corrected to V ′ _ij as the corrected luminance value V ″ _ij (step S512).

  FIG. 9 is a diagram showing an outline of a method for obtaining a linear function. When the temperature and output luminance values of the two sets of road surfaces stored in the RAM 331 are (T1, V1) and (T2, V2), respectively, two points (T1, V1), (T2) as shown in FIG. , V2) is linearly interpolated by the least square method or the like to calculate a linear function F of the temperature T and the luminance V.

The obtained linear function F is uniquely determined in the case of two-point interpolation. For example, when two points (T1, V1) and (T2, V2) are used, the linear function F for calculating the temperature T _ij corrected using the corrected luminance value V ″ _ij for each image sensor is given by (Equation 2). Can be represented.

As shown in (Expression 2), by correcting the temperature using the corrected luminance value V ″ _ij , even when different far-infrared imaging devices 1 and 1 are imaged, they are substantially the same when imaging the same object. A luminance value can be output.

  When the LSI 33 determines that it is not stored (step S510: NO), the LSI 33 returns the process to step S501 and repeats the above-described process to obtain the road surface temperature and output luminance value at the next timing. To do. The LSI 33 transmits the coefficients A and B of the linear function F shown in (Equation 3), that is, the temperature correction coefficient, to the far-infrared imaging devices 1 and 1 (step S513).

  Note that when the linear function F between the temperature T and the luminance V is calculated by linear interpolation between the two points (T1, V1) and (T2, V2) by the least square method or the like, the two points are close to each other. In some cases, the error increases. Therefore, for example, the LSI 33 calculates the temperature difference (T2−T1) at two points, and when (T2−T1) is smaller than a predetermined temperature difference (for example, 0.5 degree), the primary approximation is not performed. good.

  Hereinafter, correction processing of the output luminance signal (output value) in the signal processing unit 12 of the far-infrared imaging devices 1 and 1 will be described. FIG. 10 is a flowchart showing a procedure for correcting the luminance signal output from the signal processing unit 12 of the far-infrared imaging device 1 according to the embodiment of the present invention.

The image capturing unit 11 of the far-infrared imaging device 1 captures a front road surface having a substantially uniform temperature distribution, and an output value for each image sensor is transmitted to the signal processing unit 12. The signal processing unit 12 receives a luminance signal for each image sensor from the image capturing unit 11 (step S1001), and converts it into a digital signal V _ij (step S1002).

The signal processing unit 12 corrects the luminance signal imaged by the image imaging unit 11 using the offset correction value and the gain correction value stored in the RAM 125 (step S1003), and calculates the corrected luminance value V ″ _ij The signal processing unit 12 waits to receive the temperature correction coefficients A and B of the linear function F calculated by the arithmetic device 3 (step S1004).

When the signal processing unit 12 receives the temperature correction coefficients A and B of the linear function F (step S1004: YES), the signal processing unit 12 stores the received temperature correction coefficients A and B of the linear function F in the RAM 125. Then, the corrected temperature T _ij calculated according to ( _Equation 2) using the corrected luminance value V ″ _ij is output (step S1005).

Thereafter, the signal processing unit 12 outputs the correction temperature T _ij using the temperature correction coefficients A and B of the linear function F stored in the RAM 125. By doing in this way, even if it is different far-infrared imaging devices 1, when the same subject is imaged, it is possible to output substantially the same luminance value for the same temperature, and to The brightness, contrast, and the like of the images captured by the infrared imaging devices 1 and 1 can be substantially matched, and the obstacle detection accuracy can be improved.

  Further, when the temperature correction coefficients A and B calculated in the past are stored in the RAM 331 as history information, and the newly calculated temperature correction coefficients A and B are greatly different from the stored values. It is desirable not to transmit the newly calculated temperature correction coefficients A and B to the far-infrared imaging devices 1 and 1. This is to suppress calculation errors.

  As described above, according to the present embodiment, the output luminance values of the imaging elements of the plurality of far-infrared imaging devices 1 and 1 on the basis of the measured road surface temperature and the output luminance value of the imaging element with respect to the road surface temperature. By using the temperature correction coefficient obtained by linear interpolation, the output luminance value with respect to the measured surface temperature can be substantially matched even when the far-infrared imaging devices 1, 1,... Are different. . Therefore, the brightness, contrast, and the like of images captured by the plurality of far-infrared imaging devices 1, 1,... Can be substantially matched, and the obstacle detection accuracy can be improved.

  In the present embodiment, the temperature correction coefficients A and B of the far-infrared imaging device 1 are calculated by the computing device 3 and fed back to the far-infrared imaging device 1, but the present invention is not limited to this. The temperature correction coefficients A and B may be calculated by the image processing unit 12 in the infrared imaging device 1.

It is a figure which shows typically the structure of the far-infrared imaging system which concerns on embodiment of this invention. It is a block diagram which shows the structure of the far-infrared imaging device which concerns on embodiment of this invention. It is a block diagram which shows the structure of the signal processing part of the far-infrared imaging device which concerns on embodiment of this invention. It is a block diagram which shows the structure of the arithmetic unit of the far-infrared imaging system which concerns on embodiment of this invention. It is a flowchart which shows the process sequence of LSI of the arithmetic unit of the far-infrared imaging system which concerns on embodiment of this invention. It is a flowchart which shows the process sequence of LSI of the arithmetic unit of the far-infrared imaging system which concerns on embodiment of this invention. It is a figure which shows an example of the image imaged with the far-infrared imaging device. It is a figure which shows typically the concept of a required time calculation method. It is a figure which shows the outline | summary of the method of calculating | requiring a linear function. It is a flowchart which shows the procedure of the correction process of the luminance signal output of the signal processing part of the far-infrared imaging device which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Far-infrared imaging device 2 Speed sensor 3 Arithmetic device 9 Road surface temperature sensor 11 Image imaging part 12 Signal processing part 13 Image memory 14 Communication interface part 33 LSI
121 A / D converter 122 NUC processor 123 BPR processor 125, 331 RAM

Claims (4)

A plurality of far-infrared imaging devices that have imaging elements arranged in a matrix and that capture images of the periphery of the vehicle;
Road surface temperature measuring means for measuring the temperature of the road surface under the vehicle;
A far-infrared imaging system comprising: an arithmetic unit connected to the far-infrared imaging device and the road surface temperature measuring means so as to be able to perform data communication, and correcting and outputting an output value for each imaging device based on the measured temperature of the road surface In
A speed detecting means for detecting the speed of the vehicle;
The arithmetic unit is:
Means for specifying a measurement point displayed at a predetermined position of an image for each image data acquired from a plurality of far-infrared imaging devices;
Means for estimating the distance to the identified measurement point;
Means for calculating the time required for the identified measurement point to move to the lower part of the vehicle based on the estimated distance and the vehicle speed;
A timing means for starting timing from the time of image data acquisition;
Means for determining whether the calculated required time has elapsed;
Means for obtaining the temperature of the road surface measured by the road surface temperature measuring means when it is determined that the means has passed;
Means for calculating a correction coefficient for each image sensor based on the temperature of the road surface at a plurality of points in time and the output value of the measurement point;
Means for transmitting the calculated correction coefficient, and
The far-infrared imaging device is:
Means for receiving the calculated correction factor;
Means for correcting an output value with a received correction coefficient and outputting the corrected value to the outside. The far-infrared imaging device is:
2. The far-infrared imaging system according to claim 1, wherein a temperature of the road surface acquired at a plurality of points in time and an output value of the imaging device for the measurement point are linearly approximated to correct an output value for the temperature. . The far-infrared imaging device is:
Means for calculating the difference in temperature of the road surface acquired at a plurality of points in time;
Means for determining whether the calculated difference is smaller than a predetermined value;
The far-infrared imaging system according to claim 1 or 2, wherein when the means determines that the value is small, the output value with respect to the temperature is not corrected. A plurality of far-infrared imaging devices that have imaging elements arranged in a matrix and that capture images of the periphery of the vehicle;
Road surface temperature measuring means for measuring the temperature of the road surface under the vehicle;
A far-infrared imaging method for correcting and outputting an output value for each image sensor based on the measured temperature of the road surface, using the far-infrared imaging device and an arithmetic device connected to the road surface temperature measuring means so as to be able to perform data communication In
In the arithmetic unit,
For each image data acquired from a plurality of far-infrared imaging devices, specify a measurement point displayed at a predetermined position of the image,
Estimate the distance to the specified measurement point,
Based on the estimated distance and vehicle speed, calculate the time required for the specified measurement point to move to the bottom of the vehicle,
Start timing from the time of image data acquisition,
Determine whether the calculated time has elapsed,
If it is determined that the means has passed, obtain the temperature of the road surface measured by the road surface temperature measuring means,
Calculate the correction coefficient for each image sensor based on the temperature of the road surface at multiple points in time and the output value of the measurement point,
Send the calculated correction factor,
The far-infrared imaging device is:
Receive the calculated correction factor,
A far infrared imaging method, wherein an output value is corrected with a received correction coefficient and output to the outside.

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