JPH0518828A - Device for measuring calorific value of flame using image processing - Google Patents

Abstract

PURPOSE:To enable a calorifit value of flame to be directly calculated and inferred by processing a color image of flame for a device which detects the calorifit value of flame using image processing which is used for judging fire, etc., by calculating the calorifit value by processing the color image of flame. CONSTITUTION:A range where a brightness signal which is contained in a color image of a flame 14 exceeds a specified level is detected as a flame region, at least a ratio (G/R) of G constituent to R constituent of the color image is calculated 22 and then is converted to a distribution temperature 24. A calorifit value E is calculated 32 based on a distribution temperature T which is obtained for each picture element which is contained in the flame region and a flame area S per picture element is calculated 32, thus obtaining its total as the calorifit value of flame.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame calorific value detecting device using image processing for calculating a calorific value by processing a color image of a flame and using it for fire judgment.

[0002]

2. Description of the Related Art Conventionally, in a device for monitoring a warning area with a television camera and detecting a fire from image information of a flame captured by the television camera, generally, a brightness signal of the image is compared with a threshold value, The image portion in which the luminance signal exceeds the threshold value is determined to be the fire source. The detection of the fire source position based on the brightness signal is used, for example, for the fire source detection for controlling the fire extinguisher disclosed in Japanese Patent Laid-Open No. 1-268572.

[0003]

However, in the conventional fire detection that depends only on the luminance signal, when the luminance signal exceeds the threshold level due to light other than the fire, for example, the reflected light of headlights or sunlight. However, it is difficult to accurately distinguish the change in the brightness signal due to the fire from the change in the brightness signal due to a cause other than the fire, and there is a problem that the fire detection device using the image is not reliable enough.

The present invention has been made in view of the above conventional problems, and uses image processing in which a heat value of a flame, that is, radiant energy can be directly calculated by processing a color image of the flame. An object of the present invention is to provide a calorific value measuring device for a flame.

[0005]

To achieve this object, the present invention is constructed as follows. Incidentally, corresponding reference numerals in the embodiment drawings are also shown in parentheses. That is, the flame calorific value detection apparatus using the image processing of the present invention includes a color image pickup unit 10 for picking up a color image of a flame and a flame region in which the luminance signal included in the image of the color image pickup unit exceeds a predetermined level. The flame area detection unit 28 for detecting the ratio of the G component and the R component (G / R) or the ratio of the B component and the R component (B / R) obtained from the color imaging unit 10. 22
And a temperature conversion unit 24 for converting the ratio calculated by the ratio calculation unit 22 into a distribution temperature to obtain a distribution temperature T for each pixel,
For each pixel included in the flame region detected by the flame region detection unit 28, the total calculated by calculating the heat generation amount E based on the distribution temperature T obtained by the temperature conversion unit 24 and the flame area S per pixel is the heat generation of the flame. A calorific value calculation unit 32 for calculating the amount is provided.

Here, the ratio calculation unit 22 uses the flame area detection unit 2
The ratio may be calculated only for the region detected in 8. Further, the flame area detection unit 28 sets a threshold level approximately in the middle of the maximum brightness and the average brightness to remove ambient light and noise, and detects an area exceeding this threshold level as a flame area.

[0007]

In the present inventor, the ratio (G / R) of the R component and the G component or the B component and the R component in the color image of the flame is obtained.
It was experimentally confirmed that there is a correspondence relationship between the ratio (B / R) with the components and the flame temperature, and that each temperature can be obtained using this ratio.

Therefore, in the calorific value measuring device using the image processing of the present invention, a region in which a luminance signal in a color image picked up by a CCD color camera or the like exceeds a predetermined level is detected as a flame region, The ratio of G and R components (G / R) or the ratio of B and R components (B / R) of the color image
The distribution temperature T is calculated for each pixel based on R). If the flame region and its distribution temperature are obtained in this way, the radiant energy E from the flame region, based on Stefan-Boltzmann's law,
That is, the calorific value can be calculated. Therefore, in the present invention, the calorific value of the flame is accurately estimated by calculating the calorific value from the distribution temperature T calculated for each pixel of the flame area and the flame area S of one pixel, and cumulatively adding the calorific value to all pixels of the flame area. can do.

If the calorific value itself of the flame can be estimated in this manner, it can be appropriately judged whether it is a fire or an energy source other than the fire, and an effective method for fire monitoring can be provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an embodiment showing one embodiment of the present invention. In FIG. 1, reference numeral 10 denotes a CCD color camera as a color image pickup unit, which can obtain a color image signal composed of R, G, B color component signals according to the NTSC system, for example. When used for actual fire monitoring, the CCD color camera 10 is installed at a position overlooking the entire monitoring area.

The CCD color camera 10 performs a photographing operation at a predetermined sampling period, A / D-converts each of the obtained color images, that is, RGB signals, and then R component frame memory 16, G frame memory 18, and B component. Write to the frame memory 20. 1 when writing to this memory
The sampling number of A / D conversion of the screen sentence determines the number of pixels in one screen.

The ratio calculator 22 and the temperature converter 24 are CC
It is provided as a temperature detection unit that detects the flame distribution temperature from the image of the D color camera 10. That is, the ratio calculator 2
In the case of 2, the ratio G / R of the G component and the R component at the same pixel position obtained by reading the G component frame memory 18 and the R component frame memory 16 is calculated. From the G / R ratio calculated by the ratio calculator 22, the distribution temperature T for each pixel can be obtained according to the conversion characteristic diagram shown in FIG.

Specifically, a conversion table having the conversion characteristics shown in FIG. 2 is provided in the temperature conversion section 24, and the conversion table is accessed by the G / R value obtained by the ratio calculation section 22. The distribution temperature according to the characteristics of FIG. 2 can be obtained for each pixel. The characteristic diagram of FIG. 2 is obtained experimentally, and the characteristic curve can be approximated by the following equation, where the horizontal axis x is the distribution temperature and the vertical axis y is the ratio (G / R). y = 5.37 × 10 ⁻¹⁶ x ⁵ −1.78 × 10 ⁻¹² x ⁴
+5.88 x 10 ^-13 x ³ -4.76 x 10 ^-6 x ² +
2.68 × 10 ⁻² x−27.4 Incidentally, the distribution temperature may be obtained using the characteristic conversion diagram of the B / R ratio obtained experimentally shown in FIG. 7.

On the other hand, the flame area detection unit 28 extracts, as a flame area, an area of the G component stored in the G component frame memory 18 that exceeds a prescribed threshold level. The threshold level for detecting the flame area is an intermediate level between the maximum brightness and the average brightness to remove ambient light and noise, for example, threshold level = (maximum brightness + average brightness) / 2.

It is assumed that the distribution temperature T for each pixel included in the flame detection region obtained by the temperature conversion unit 24 is given to the heat generation amount calculation unit 32, and the flame area S per pixel in the flame region is known in advance. , The heat value E of the flame is calculated based on Stefan-Boltzmann's law. That is, Stefan-Boltzmann's law is given by the following equation, where T is the temperature of the flame. E = ε × σ × S × T ⁴ [watt] (1) where σ = (π ⁵ k ⁴ ) / (15c ² h ³ ) [jm ⁻² s ⁻¹ k ⁻⁴ ] S: surface area ε of flame : Emissivity Here, the emissivity ε and σ are treated as constants.

FIG. 3 shows an example of the flame area 48 extracted from the image of the G component frame memory 18 by the flame area detecting section 28. Regarding the pixels in the shaded area in this flame area 48,
The integral calculation of (S × T ⁴ ) in the equation (1) may be executed using the distribution temperature obtained by the temperature conversion unit 24.
Specifically, the constant (ε × σ) may be multiplied for each (S × T ⁴ ) pixel obtained for each pixel in the flame region 48. That is, The calorific value of the flame is calculated as. However, n is the number of pixels in the flame region.

FIG. 4 is an example of experimental data for supporting the correspondence between the ratio (G / R) of G and R components of a color image and the actual distribution temperature in the present invention. The data in Fig. 4 was taken with a CCD color camera of a diffuser plate illuminated with an incandescent lamp.
A conversion value is plotted according to the characteristic diagram of FIG. 2 for each pixel of the number of pixels shown on the horizontal axis of each of 100 lines, 200 lines, 300 lines and 400 lines of the screen vertical axis, and a line of 2200K is radiated. It is the actual surface temperature measured by a thermometer.

As is clear from this characteristic, the ratio (G /
The variation of the converted distribution temperature obtained from R) with respect to 2200K is within ± 50K, which is sufficiently practical. In Fig. 5, ethanol is used as a combustion material, and the calorific value per unit fuel is known by changing the diameter of the vessel that determines the size of the flame and burning. Therefore, the calorific value per unit time A [calculated from the fuel decrease amount] KW] and the experimental data of the calorific value B [KW] obtained by using the temperature detection based on the (G / R) ratio of the present invention with the emissivity ε = 1, and the flame as a plane. The emissivity ε of the flame when considered is shown as ε = A / B. Therefore, if ε = 0.2 is used as the emissivity ε obtained from the experimental data, the actual heat generation amount can be obtained by image processing.

Similar to FIG. 5, FIG. 6 shows experimental data when the combustion material is normal heptane.

[0020]

As described above, according to the present invention, the calorific value of the flame can be accurately estimated by using the temperature obtained from the G / R ratio or the B / R ratio of the flame region, If, for example, a fire is monitored using this heat generation amount, it is possible to make a very reliable fire judgment.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment showing a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing conversion characteristics of G / R ratio and distribution temperature used for temperature detection in the embodiment of FIG.

FIG. 3 is an explanatory diagram showing a flame region extracted from an image.

FIG. 4 is an explanatory diagram showing a correspondence between a distribution temperature obtained from a G / R ratio obtained from a color image and a temperature measured by a radiation thermometer.

FIG. 5 is an explanatory view showing the data of the calorific value obtained from the fuel decrease amount when ethanol is burned and the calorific value obtained when ε = 1 in the present invention, for comparison.

FIG. 6 is an explanatory view showing the data of the calorific value obtained from the fuel decrease amount when burning normal heptane and the calorific value obtained when ε = 1 in the present invention, for comparison.

7 is a characteristic diagram showing conversion characteristics of B / R ratio and distributed temperature used for temperature detection in the embodiment of FIG.

[Explanation of symbols]

10: CCD color camera (color imaging unit) 14: Flame 16: R component frame memory 18: G component frame memory 20: B component frame memory 22: Ratio calculation unit 24: Temperature converter 28: Flame area detection unit 32: Radiant energy calculator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Taku Watanabe             2-1043 Kamiosaki, Shinagawa-ku, Tokyo Ho             Chiki Co., Ltd.

Claims (3)

[Claims] 1. A color image pickup section for picking up a color image of flame, a flame area detection section for detecting a range in which a luminance signal included in an image of the image pickup section exceeds a predetermined level as a flame area, and a color image pickup section obtained from the image pickup section. Ratio of G component and R component (G /
R) or a ratio calculation unit that calculates the ratio of the B component and the R component (B / R), and the ratio calculated by the ratio calculation unit is converted into a distribution temperature to be 1
A temperature conversion unit for obtaining a distribution temperature T for each pixel, and a distribution temperature T obtained by the temperature conversion unit and a flame area S per pixel for each pixel included in the flame region detected by the flame region detection unit. 2. A flame calorific value measuring device using image processing, comprising: a calorific value calculation unit that calculates a sum of calculated calorific values E as a calorific value of the flame. 2. A flame calorific value measuring apparatus using image processing according to claim 1, wherein the ratio calculation unit calculates a ratio only for the area detected by the flame area detection unit. An apparatus for measuring the calorific value of a flame using image processing. 3. A flame calorific value measuring apparatus using the image processing according to claim 1, wherein the flame area detection unit sets a threshold level at approximately the middle of maximum brightness and average brightness, and the threshold level is set. An apparatus for measuring a calorific value of a flame using image processing, characterized by detecting a region exceeding the range as a flame region.