JPH0843209A - Image processing device - Google Patents

Abstract

(57) [Summary] [Object] To provide an image processing apparatus which can easily obtain the temperature and emissivity of an object by using an output signal of a solid-state image sensor. A solid-state image sensor 1 having two different spectral sensitivity characteristics, a signal level adjusting circuit 4 for adjusting a signal level of an output from the solid-state image sensor 1, and a solid-state image sensor 1
Image correction circuits 5 and 6 for obtaining and storing sensitivity correction data from the size of the output signal, output signals with different spectral sensitivity characteristics output from the solid-state imaging device 1, and sensitivity corrections previously stored in the image correction circuits 5 and 6. An image calculation circuit 8 for obtaining the temperature and the emissivity of the object from the data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus,
In particular, the present invention relates to an image processing apparatus that determines the temperature and emissivity of an object without contacting the object by using a solid-state image sensor such as a CCD.

[0002]

2. Description of the Related Art Conventionally, the temperature of an object to be measured in a non-contact manner with a solid-state image sensor such as a CCD is calculated from a black body radiation equation assuming that the emissivity of the object is 1.0. Often. However, since the actual emissivity of the object takes a value from 0.0 to 1.0, there is a problem that a large error occurs between the calculated temperature and the actual temperature.

The following is a conventional technique related to such a problem.

According to the technique disclosed in Japanese Patent Laid-Open No. 60-014578, a plurality of infrared solid-state image pickup elements having different infrared spectral sensitivity characteristics are used to pick up the same heat ray image of the object to be shot. The temperature distribution of the object can be obtained, and the absolute temperature value of the object to be photographed is also obtained from the image signals of the object to be photographed, which are output by the plurality of infrared solid-state image pickup devices, without depending on the reference temperature black body.

In the technique described in Japanese Patent Application Laid-Open No. 02-153692, detection means for detecting illumination light from a light emitting source which periodically emits light is provided and a color temperature conversion table corresponding to a light source similar to black body radiation is stored. The output data obtained from the storage unit having a value according to the detected color temperature is corrected based on the detection output from the detection unit. And CCD
A picked-up image signal of a subject picked up by a solid-state image pickup device such as the above is input to the picked-up image signal processing circuit unit and subjected to various kinds of signal processing such as white balance adjustment. The state of the incident light at the time of imaging the subject is detected by the illumination light detection means, the incident light is separated into color components, and the measured values for the red component and the blue component are amplified to a predetermined signal level via a preamplifier, After removing the ripple component with a low pass filter,
Input to the microprocessor via the / D converter.

The microprocessor uses the color temperature conversion table showing the correspondence between the colorimetric data corresponding to the light source approximate to the black body radiation and the white balance control value, and the signal inputted via the A / D converter. A fluorescent lamp detector that detects whether or not the illumination light is due to a light emitting source that periodically emits light,
And a correction circuit that corrects the data output from the color temperature conversion table according to the output of the fluorescent lamp detector.

The microprocessor obtains a white balance control value according to the colorimetric data by searching the color temperature conversion table. At this time, when the fluorescent light detector detects that the illumination light is from the fluorescent light that periodically emits light, the microprocessor drives the correction circuit to set the data obtained from the color temperature conversion table to the predetermined value. Is added or subtracted to correct the white balance control value. The white balance control value thus obtained by the microprocessor is given to the image pickup signal processing circuit section via the D / A converter, and is used for white balance adjustment for the image pickup input from the solid-state image pickup device. It

In the technique described in Japanese Patent Laid-Open No. 02-153693, detection means for detecting illumination light from a light emitting source that periodically emits light is provided, and a color temperature conversion table corresponding to a light source similar to black body radiation is stored. Data corresponding to the detected color temperature is selectively supplied from the first storage means having a value or the second storage means having a color temperature conversion table corresponding to the spectral characteristic of the light emitting source that periodically emits light as a storage value. I try to ask.

This technique is disclosed in the above-mentioned Japanese Patent Laid-Open No. 02-15369.
The configuration of the microprocessor is different from that of the technique described in Japanese Patent No. 3 publication, and a first color temperature conversion table showing a correspondence relationship between color measurement data and a white balance control value corresponding to a light source similar to black body radiation. And a second color temperature conversion table showing a correspondence relationship between the color measurement data corresponding to the spectral characteristic having a strong power in a specific wavelength band of a fluorescent lamp and the white balance control value, and the A / D converter. The selector is driven to selectively take out data from the first or second color temperature conversion table according to the identification information of the light emitting source detected by the fluorescent lamp detector which inputs the signal from . This microprocessor selectively obtains a white balance control value according to the color measurement data from the first or second color temperature conversion table. The white balance control value thus obtained by the microprocessor is given to the imaging signal processing circuit section via the D / A converter,
It is used for white balance adjustment for an image picked up from the solid-state image sensor.

In the technique described in Japanese Patent Application Laid-Open No. 04-150567, a color separation of an input color image is performed to generate a first color separation signal, and a second color is calculated from the first color separation signal by a correction operation. A correction calculation unit that obtains a separation signal and a color image output unit that outputs a color image to an output medium based on the second color separation signal are provided. By changing the correction calculation condition of the correction calculation unit, the input color can be obtained. The tone of a specific hue of an image is corrected.

FIG. 4 shows the configuration of a conventional infrared image pickup device described in the above-mentioned Japanese Patent Laid-Open No. 60-014578. FIG.
In, the heat rays that have passed through the infrared lens 2 from the object 50 are divided into three directions by the infrared beam splitters 8 and 9, and the infrared solid-state imaging device 10 uses the infrared bandpass filter 13 to detect the object 50 of the object 50. λ ₁ ± Δ
An infrared image having a wavelength of λ _1/2 is formed, and the infrared solid-state image pickup device 11 has an infrared bandpass filter 14
λ ₂ ± Δλ _2/2 infrared image wavelength is tied, in the infrared solid-state imaging device 12, by an infrared band-pass filter 15, an infrared image of the wavelength of λ ₃ ± Δλ _3/2 is tied. In short, these infrared solid-state imaging devices 10, 11,
The infrared bandpass filters 13, 14 and 15 have different infrared spectral sensitivity characteristics from each other. Then, from the infrared solid-state image sensor 10, λ ₁ ± Δ
An image signal I ₁ of an infrared image having a wavelength of λ _1/2 is output to the signal processing circuit 16, and the infrared solid-state image pickup device 11 outputs λ ₂ ±.
[Delta] [lambda] ₂ / image signals I ₂ infrared image of the wavelength of 2 is output to the signal processing circuit 16, lambda ₃ from the infrared solid-state imaging device 12
± Δλ _3/2 of the image signals I ₃ of the infrared image of the wavelength is outputted to the signal processing circuit 16. In the signal processing circuit 16, the image signals I ₁ , I ₂ , and I ₃ output from the infrared solid-state image pickup devices 10, 11, and 12 are image signals I indicating the temperature distribution of the object 50, and absolute values of the object 50. A signal indicating the temperature T,
It is converted into a signal indicating the emissivity ε of the object 50 and output.

[0012]

Problems to be Solved by the Invention JP-A-60-0145
In the technique described in Japanese Patent Publication No. 78, the absolute temperature of the object to be photographed is emissivity unless the background temperature of the object to be photographed is set externally by using three infrared solid-state image pickup devices having different infrared spectral sensitivity characteristics. In the case of using an infrared solid-state image sensor having two different infrared spectral sensitivity characteristics, the background temperature and the emissivity of the object to be photographed must be set externally. There is a problem that the absolute temperature cannot be obtained. Moreover, no specific configuration is shown for the signal processing circuit.

In the techniques described in Japanese Patent Application Laid-Open Nos. 02-153692 and 02-1533693, when illumination light from a light emitting source that periodically emits light is not used,
The signal processing circuit is no different from the conventional device and does not calculate the temperature and the emissivity of the subject.

According to the technique disclosed in Japanese Patent Laid-Open No. 04-150567, it is only necessary to provide a correction calculation unit for the spectral sensitivity characteristic of the image input device and the spectral sensitivity characteristic of the developing unit used for output, and the object of the image data There is a problem that nothing is mentioned about the conversion method to the physical quantity that the object itself has such as temperature and emissivity.

An object of the present invention is to use an infrared solid-state image sensor having two different infrared spectral sensitivity characteristics,
Provided is an image processing circuit capable of determining the temperature and emissivity of an object by performing processing with sensitivity correction data stored in the image correction circuit in advance and then performing calculation processing set by the image calculation circuit. To do.

[0016]

An image processing apparatus according to the present invention comprises a solid-state image pickup device composed of pixels having two different spectral sensitivity characteristics, and a photoelectric conversion signal of the solid-state image pickup device so that the photoelectric conversion signals can be sequentially read. A driver circuit for driving the solid-state image pickup device, an image correction circuit for obtaining and storing sensitivity correction data from the magnitude of the output signal of the solid-state image pickup device, and a spectral sensitivity for outputting the temperature and emissivity of an object by the solid-state image pickup device. It is characterized by comprising an image calculation circuit which is obtained from output signals having different characteristics and the sensitivity correction data stored in advance in the image correction circuit.

[0017]

By using two infrared solid-state image pickup devices having infrared spectral sensitivity characteristics different from each other, processing with sensitivity correction data stored in advance in the image correction circuit is performed, and then calculation processing set in the image calculation circuit is performed. This allows the temperature and emissivity of the object to be determined.

[0018]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. This image processing apparatus includes an infrared solid-state image sensor 1 and
The driver circuit 2, the reference signal generation circuit 3, the signal level adjustment circuit 4, the image correction circuits 5 and 6, the data selector circuit 7, the image calculation circuit 8, the signal output circuit 9, the computer 10, and the control. It is composed of a bus 11 and a camera bus 12.

The infrared solid-state image pickup device 1 is composed of pixels having two different infrared spectral sensitivity characteristics. As such a solid-state image sensor, a Schottky junction type solid-state image sensor having different barrier heights is used.

The driver circuit 2 constitutes a signal reading mechanism for driving the solid-state image pickup device so that the photoelectric conversion signals of the solid-state image pickup device 1 can be sequentially read out.

The signal level adjusting circuit 4 includes the solid-state image pickup device 1.
The image correction circuits 5 and 6 are adjusted by adjusting the signal level of the output from
Send to

The image correction circuits 5 and 6 are provided with a processing mechanism for obtaining sensitivity correction data from the magnitude of the output signal of the solid-state image pickup device 1, store the obtained sensitivity correction data, and output the sensitivity correction data and the solid-state image pickup device. The signal is sent to the data selector circuit 7.

The data selector circuit 7 transfers the sensitivity correction data stored in the image correction circuits 5 and 6 to the image calculation circuit 8 and uses the output signal from the solid-state image pickup device 1 to detect the image calculation circuit 8. The calculation procedure is switched.

The image calculation circuit 8 has a plurality of calculation procedures, and from the output signals output from the solid-state image pickup device 1 having different spectral sensitivity characteristics and the sensitivity correction data stored in advance in the image correction circuits 5 and 6, Find the temperature and emissivity of the object.

The signal output circuit 9 adjusts the output level of the image calculation circuit 8 and adds a video signal.

Next, the operation of this embodiment will be described.

The solid-state image pickup device 1 is driven by the driver circuit 2 and the reference signal generation circuit 3, and the output of the solid-state image pickup device 1 is adjusted in signal level by the signal level adjustment circuit 4. The image correction circuit 5 and the image processing circuit 6 respectively process image pickup signals having different spectral sensitivity characteristics. The data selector circuit 7 uses the image pickup signals from the image correction circuits 5 and 6 to obtain an image calculation circuit 8 for obtaining the temperature and emissivity of the object.
The calculation procedure of is switched. By having a plurality of calculation procedures, the image calculation circuit 8 can instantaneously compare the temperature and emissivity of the object with the object temperature image obtained by assuming the conventional emissivity. The signal output circuit 9 adjusts the output level of the image calculation circuit 8 and adds a video signal. The computer 10 has a control bus 1
The calculation result is passed and the condition of the device is set via 1. The camera bus 12 transfers the control signal from the reference signal generator 3.

Next, the principle of the embodiment of the present invention shown in FIG. 1 will be described. 2 and 3 are explanatory views of an example of the principle operation for obtaining the temperature and the emissivity of the object in the present invention. The number N of output electrons per pixel of the solid-state imaging device 1 is expressed by the formula (1) when the object to be measured is in a thermal equilibrium state and the thickness in the optical path direction is sufficient and it can be assumed that it is an opaque material (τ _obj = 0). And (2).

[0030]

[Equation 1]

In the equation (1), A _sen is the sensor area, ff
_sen represents the fill factor, and t _sen represents the integration time. In equation (2), T _obj and ε _obj are the temperature and emissivity of the object, T _sun and sr _sun are the blackbody temperature and the average solid angle of the _sun , and T _air and s _air are the atmospheric temperature and the contribution of scattering. Represent each rate. Further, the black body radiation per unit solid angle of the temperature T is expressed by the formula (3), and the sensor response is expressed by the formula (4) (C ₁ : quantum efficiency,
φ _SB : Barrier height), the average solid angle of the sun is calculated by the formula (5) (R
_O : radius of the sun, r _au : average distance between the sun and the earth), transmittances of filters and lenses τ _fil (λ), τ _len (λ) are measured values, and wavelength ranges λ ₁ to λ ₂ (3 ~ 5 [μ
m]) is integrated.

FIG. 2 shows the emissivity dependence of the incident spectral illuminance per unit area and unit solid angle obtained from these equations.
From this figure, the spectral illuminance in the 3 to 5 [μm] band decreases as the emissivity increases, and the value of the emissivity of the object greatly affects the value of the incident illuminance. Therefore, in order to obtain an accurate temperature of the object from the actual thermal imaging, it is necessary to simultaneously obtain the emissivity of the object.

Therefore, in order to study the influence of the sensor characteristics on the number N of output electrons, the equation (1) is transformed into the equation (6).

[0034]

[Equation 2]

It can be seen that the number of output electrons N is composed of the coefficient a ₀ multiplied by the emissivity of the object expressed by the equation (7) and b ₁ and b ₂ which can be treated as constants with respect to the emissivity. Constants b ₁ and b
_From equations (8) and (9), ₂ contributes the sunlight component and the scattering component, respectively, and can be treated as a constant for the temperature of the object. FIG. 3 shows the temperature and emissivity dependence of the coefficient a ₀ calculated using a standard optical system and sensor characteristics.

As a result of analyzing the relational expressions shown in the present invention for the optical system having various characteristics and the sensor characteristics, the coefficient a ₀ can be expressed by a quadratic function with respect to the object temperature, and with respect to the emissivity. It was found that can be expressed by a linear function.

From this, the temperature and the emissivity of the object can be obtained by setting only the atmospheric temperature from the measured values by the infrared solid-state image pickup device 1 having two different infrared spectral sensitivity characteristics.

In order to have different infrared spectral sensitivity characteristics, a Schottky junction type infrared solid-state image pickup device having different barrier heights or other infrared solid-state image pickup devices, or a combination thereof. You may use it.

In order to have infrared spectral sensitivity characteristics different from each other, a bandpass filter having infrared transmission characteristics, a long wavelength cut filter, a filter having other transmission characteristics such as a short wavelength cut filter may be used. Well, they may be used in combination.

Further, in this embodiment, the sensitivity correction data is obtained by the image correction circuit, but it may be obtained by an external processing device via the data transfer mechanism.

In the present embodiment, the optical system (not shown) may be a lens, a reflecting mirror, another optical system, or a combination thereof.

[0042]

As described above, the image processing apparatus according to the present invention uses two infrared solid-state image pickup devices having infrared spectral sensitivity characteristics different from each other and the sensitivity correction data stored in advance in the image correction circuit. After performing the processing, by performing the arithmetic processing set by the image arithmetic circuit, it is possible to determine the temperature and the emissivity of the object.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a principle operation for obtaining an object temperature and an emissivity in the present invention.

FIG. 3 is an explanatory diagram of a principle operation for obtaining an object temperature and an emissivity in the present invention.

FIG. 4 is a block diagram of an example of a conventional image processing apparatus.

[Explanation of symbols]

 1 solid-state image sensor 2 driver circuit 3 reference signal generation circuit 4 signal level adjustment circuit 5, 6 image correction circuit 7 data selector circuit 8 image operation circuit 9 signal output circuit 10 computer 11 control bus 12 camera bus

Claims (3)

[Claims] 1. A solid-state image sensor including pixels having two different spectral sensitivity characteristics, a driver circuit for driving the solid-state image sensor so that photoelectric conversion signals of the solid-state image sensor can be sequentially read, and the solid-state image sensor. An image correction circuit that obtains and stores sensitivity correction data from the magnitude of the output signal of the image pickup device, and an image correction circuit that outputs the temperature and emissivity of the target object in advance with the output signal of different spectral sensitivity characteristics output from the solid-state image pickup device. An image processing device which is obtained from the sensitivity correction data stored in the image processing circuit. 2. The image processing apparatus according to claim 1, wherein two solid-state image pickup devices having different spectral sensitivity characteristics have different spectral sensitivity characteristics. 3. The image processing apparatus according to claim 1, wherein the spectral sensitivity characteristics are made different by spectral filters having different spectral sensitivity characteristics.