JPH0830681B2 - Fume transmittance measuring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a haze transmittance measuring device for measuring haze transmittance on a road, for example, by performing pattern processing on a captured image.

[Conventional technology]

FIG. 4 shows a conventional haze transmittance measuring device. In the figure, 5 is a projector, 6 is a light receiver, and 7 is a controller. As shown in FIG. 5, the light projector 5 comprises a light controller 9, a light emitting element 8 for generating light controlled by the light controller 9, and a light projecting lens 10. The light receiver 6 includes a light receiving lens 11, a light receiving element 12, and a synchronization control unit that receive light from the light projector 5.
It consists of thirteen. Further, the control unit 7 includes a power supply unit 14 and a light receiver 6.
And a display unit 16 such as a voltmeter for displaying the transmittance.

Next, the operation will be described. From the light emitting element 8 of the light projector 5, modulated light according to a control signal from the light control unit 9 is emitted toward the light receiver 6. The emitted light I ₀ is scattered by rain, snow, fog, smoke, etc. (hereinafter, abbreviated as fog) in the atmosphere,
The light is absorbed and reaches the light receiver 6 as light I, and the light receiving element 12
And is converted into light and electricity and amplified by a preamplifier (not shown). Then, from the amplified optical information, only the modulated light from the projector 5 is extracted by the synchronization control unit 13 and sent to the control unit 7. In the control unit 7, the light reception signal from the light receiver output is converted into a transmittance value by the transmittance calibration unit 15, and this transmittance is output as a voltage.
To be displayed.

[Problems to be solved by the invention]

Since the conventional fume transmittance measuring device is configured as described above, it is necessary to adjust the optical axes of the projector 5 and the light receiver 6 with high accuracy (optical axis alignment), and the output display unit
Since 16 is a 100% arbitrary scale, there was a problem that it was necessary to calibrate the difference in output level due to the difference in the installation span depending on the installation location for each installation location.

The present invention has been made to solve the above-mentioned problems, and eliminates the laborious work of aligning the optical axis and calibrating the installation span in the above-mentioned conventional technique, and allows easy and quick operation of the smoke transmittance. The purpose is to obtain a fume transmittance measuring device that can be measured by.

[Means for solving problems]

The haze transmittance measuring apparatus according to the present invention is provided with an indicator having an alternating pattern of white and black, and this indicator is photographed by a television camera through an atmosphere containing haze and the like, and image information of the photographed indicator is displayed. First, the image processing apparatus is configured to calculate the haze transmittance.

[Action]

The image processing device in this invention, from the degree of density of the image pattern which is the image information of the mark having the alternating pattern of white and black obtained by shooting with the television camera, the transmittance by light according to the density of the fog, Operates according to a pre-programmed calculation method.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.
In FIG. 1, 1 is a TV camera, 2 is a mark installed near the road so as to face the TV camera 1, and for example, as shown in FIG. It consists of a drawing on a board. 3 is based on the image information of the index 2 taken by the TV camera 1,
It is an image processing apparatus for calculating the transmittance of smoke due to light by calculation. In this image processing device 3, 3a is an analog / digital converter for digitally converting the output of the television camera 1.
Digital (A / D) converter, 3b is an image memory, 3c is an analog output converter, 3d is a digital output converter, and 3e is a microprocessor (CPU) that executes substantial arithmetic processing described later. .

 Next, the operation will be described.

The image information of the mark 2 photographed by the television camera 1 is sent to the image processing device 3, and the pattern information obtained by scanning the mark shown in FIG. Then, the brightness ratio of the white and black patterns is obtained by an arithmetic expression according to the following equation, and the smoke transmittance is obtained from this.

Next, the processing procedure of the transmittance measurement by the image processing apparatus 3 will be described according to the flow chart of FIG.

The image processing device 3 converts the two-dimensional (surface) information captured by the TV camera 1 into 256 × 256 pixel information (the level of one pixel has 0 to 256 gradations (8 bits)),
After that, processing is performed as digital information.

That is, first, the mark 2 in FIG. 1 is projected by the television camera 1 as the mark pattern 4, and this is cyclically converted into 256 × 256 × 8 digital information by the hardware (step ST1). ). The standard conversion cycle is 1/30 second.

Next, as the minimum information necessary for the image processing, one horizontal row of data AA 'of the marking pattern 4 can be used, but here, the upper and lower two or three rows are fetched as data (step ST2). This range can be specified according to the installation conditions, measurement range, etc. The data obtained in this way, that is, A-
A ′ The data of the upper and lower two or three columns adjacent to one horizontal line are added in the vertical direction and divided by the number of columns. That is, they are averaged and converted into one-dimensional information (step ST3). These one-dimensional data Fast Fourier transform is performed by the following equation (step ST
Four). Here, IP (I) is image data obtained as the one-dimensional data, an integer from 0 to 255, N is the number of data (256 = N), and K is a frequency component included.

Next, using the obtained real part R (K) and imaginary part J (K), The power spectrum is calculated from (step ST5). The power spectrum Z (K) here corresponds to the absolute value of the amplitude of the frequency component included in the one-dimensional data when the one-dimensional data is regarded as a first-order periodic function.

Therefore, the order (frequency) corresponding to the pattern of Mark 2
The power spectrum of is equivalent to the level of the white part in the primary data obtained from AA ′ above, and by taking the ratio with the power spectrum of 0th order (DC component), the white and black of Mark 2 can be directly measured. It is equivalent to taking the lightness ratio CCMZ of the part (step ST6).

The brightness ratio CCMZ is calculated from CCMZ = 2MZ / (Z (O) + MMZ). Where MZ is the sum of the power spectra, And MMZ is the average value of the power spectrum, and MMZ = MZ / ND.

And finally, in the power spectrum ratio,
Actually, the best time of the transmittance is set to 100, and the transmittance is obtained by comparing with the measured time (step ST7).
Then, 0 to 100% of these are analog output (voltage or current) by an analog output converter.
Then, each is converted into a digital output by the digital output converter and output.

In the above embodiment, the black-and-white alternation pattern on the indicator 2 is shown as one type, but a plurality of black-and-white alternation patterns on the indicator 2 may be provided. It is possible to obtain the power spectrum for the pattern of the period and obtain the fume transmittance from the respective differences, and the same effect as that of the above-described embodiment is obtained.

〔The invention's effect〕

As described above, according to the present invention, the mark having the alternating pattern of white and black is photographed by the television camera through the atmosphere including the fog and the white and black of the mark photographed by the image processing device. A power spectrum corresponding to the amplitude of the frequency component when multiple one-dimensional data are extracted and averaged, and the one-dimensional data is regarded as a primary frequency function from the averaged one-dimensional black and white data. And the ratio with the 0th order power spectrum is calculated,
Since it is configured to calculate and output the haze transmittance from the ratio, the haze transmittance can be measured without complicated work such as alignment of the optical axis, and moreover, one-dimensional data of multiple lines is averaged. Since the haze transmittance is calculated from this, there is an effect that it can be measured with high accuracy.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a fume transmittance measuring apparatus according to an embodiment of the present invention, FIG. 2 is a front view of a mark in the present invention, and FIG. 3 is a flow chart for explaining an image processing procedure in the present invention. FIG. 4 is a block diagram showing a conventional fume transmittance measuring device, and FIG. 5 is a block diagram showing details of FIG. 1 is a television camera, 2 is an index, and 3 is an image processing device. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A mark having an alternating pattern of black and white, a television camera for photographing the mark through an atmosphere containing smoke and the like, and a one-dimensional black and white image of the mark photographed by the television camera. A plurality of data are extracted and averaged, and a power spectrum corresponding to the amplitude of the frequency component is calculated from the averaged white and black one-dimensional data when the one-dimensional data is regarded as a linear frequency function. In addition, a fume transmittance measuring device comprising: an image processing device that calculates a ratio of the zero-order power spectrum and calculates and outputs the haze transmittance from the ratio.