JP2010091470A - System and method of measuring gas concentration by electronic image colorimetric method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate accurate measurements of gas concentration. <P>SOLUTION: A gas concentration sensing sheet 40, where a sensing paper 41 for changing its color according to the amount of ozone exposure, and color samples 42, 43, 44 colored by corresponding to a known amount of ozone exposure are disposed, is photographed by an image input device 30. The color information of the sensing paper 41 is compared with that of the color samples 42, 43, 44 by a gas concentration measuring device 10 to calculate ozone concentration, thus measuring the ozone concentration without the use of large-sized expensive devices. Also, markers 45A, 45B, 45C, 45D are disposed on the gas concentration sensing sheet 40, and relative coordinates are set onto electronic image data, obtained by photographing the gas concentration sensing sheet 40, based on the markers 45A, 45B, 45C, 45D, thus analyzing the electronic image data by taking into consideration the photographic size, photographic angle, and image rotation. As a result, since a photographer is able to readily utilize the gas concentration measuring device, without bothering about photographing. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for measuring a gas concentration by a colorimetric method.

At present, air pollution due to NO _x , SPM (Suspended Particulate Matter), and photochemical oxidant occurs, and the influence on the environment has become a problem. Ozone gas is the main component of photochemical oxidants (O ₃₎ is factory, pollutants such as NO _x and hydrocarbons discharged from offices and automobiles upon exposure to sunlight is generated to cause a photochemical reaction, photochemical Causes smog. Also, in various devices equipped with corona discharge means, such as electrostatic copying machines, laser printers, LED facsimiles, etc., ozone gas and NO _x gas are generated during the operation of the corona discharge means. Ozone gas has a strong oxidizing ability, so if the concentration in the air exceeds a certain level (0.1 ppm), it stimulates the respiratory system due to its toxicity, and even if it is inhaled for a long time, it is considered harmful. Yes.

  For this reason, it is necessary to monitor the environment by investigating the concentration distribution of harmful gases such as ozone gas, assessing the impact on the global environment, and assessing the impact of personal ozone gas exposure. Various ozone concentration measuring devices that are inexpensive, small and light, and can be used in individuals and homes have been developed for ozone gas (see, for example, Patent Documents 1 to 4).

  As an ozone concentration measuring device, a simple measuring device shown in FIG. 11 has been proposed. The ozone concentration measuring device 100 shown in the figure includes a detection paper 112 that fades when exposed to ozone gas, and color samples 113, 114, and 115 corresponding to the concentration of ozone gas on a mount 111. The detection paper 112 is prepared by impregnating a cellulose filter paper with a detection solution prepared by adding a dye, a moisturizing agent, an acid, water, or the like that fades when it reacts with ozone gas, and air drying. Indigo dyes, azo dyes, triphenylmethane dyes, anthraquine dyes and the like are used as the dyes that change color when reacted with ozone gas.

  Each of the color samples 113, 114, and 115 is composed of colors corresponding to different ozone exposure amounts, for example, 0 ppbh, 400 ppbh, and 800 ppbh (ppbh is a product of accumulated ozone concentration that is a product of ozone concentration ppb and exposure time hour). Unit). The color sample 113 has an ozone exposure amount of 0 ppbh, that is, the same color (indigo carmine: indigo) as the detection paper 112 before measurement. The color samples 114 and 115 exhibit colors when the ozone exposure amount of the detection paper 112 is 400 ppbh and 800 ppbh, respectively.

When the ozone concentration measuring device 100 is used for a certain period of time (for example, 8 hours) in an environment where ozone gas exists, the detection paper 112 is exposed to ozone gas and fades. The exposure amount of ozone gas can be known by comparing the color of the detection paper 112 that has faded with the color samples 113, 114, and 115. That is, when the detection paper 112 fades and becomes the same color as the color sample 114, it is determined that the ozone exposure amount is 400 ppbh. When the detection paper 112 is substantially equal to the intermediate color between the color samples 114 and 115, it is determined that the ozone exposure amount is 600 ppbh between 400 ppbh and 800 ppbh. In order to convert the exposure amount into a concentration, the exposure amount is divided by the elapsed time and obtained as an average concentration per exposure time.
JP 2004-144729 A International Publication No. 06/016623 Pamphlet JP 09-274032 A Japanese Patent Laid-Open No. 2000-081426 Tanaka Shigenori, 6 others, “Chapter 3 Introduction to Image Processing 1”, [online], August 11, 2003, Microsoft Corporation, [October 1, 2008 search], Internet <URL: http: / /www.microsoft.com/japan/msdn/academic/Articles/Algorithm/03/> Hany Farid, "Fundamentals of Image Processing", [online], [October 1, 2008 search], Internet <URL: http://www.cs.dartmouth.edu/farid/tutorials/fip.pdf>

  However, when the detection paper 112 of the ozone concentration measuring device 100 and the color samples 113, 114, and 115 are visually compared, it is possible to know an approximate value but not a detailed numerical value. For accurate ozone concentration calculation, a reflection spectrum is measured with a spectrophotometer, or a dedicated reflectance measuring device that irradiates the detection paper 112 with LED light of a specific wavelength and measures the reflected light with a photodiode is used. There is a need.

  Further, the detection paper 112 is not suitable for continuous automatic measurement because it is taken out one by one from a state stored in a sealed container such as aluminum so as not to be exposed to the outside air, and is placed on the mount 111 for use.

  The present invention has been made in view of the above, and an object thereof is to simplify accurate gas concentration measurement.

  A gas concentration measurement system according to a first aspect of the present invention includes a detection region whose color changes in accordance with a gas exposure amount, a reference region having a color corresponding to at least two known exposure amounts, a detection region, and a reference region. A gas exposure amount detection means having a marker for specifying a position; an input means for receiving input of image data obtained by photographing the gas exposure amount detection means; and a detection region and a reference region by specifying the position of the marker in the image data. Area specifying means for specifying the corresponding areas; extraction means for extracting color information at positions corresponding to the detection area and at least two reference areas from the image data; and color information of the detection area as color information of the reference area. And calculating means for calculating the amount of gas exposure by applying the relative value to a conversion formula.

  In the gas concentration measurement system, there is orientation detection means for setting relative coordinates in the image data based on the position of the marker in the image data, and the area specifying means is based on the relative coordinates. It is characterized by specifying.

  In the gas concentration measurement system, the gas exposure amount detection means has a single color blank area around the detection area and the reference area, extracts the color information of the blank area from the image data, and based on the color information of the blank area. And an illuminance correction unit that obtains an illuminance distribution pattern of the image data and applies image processing to the image data to make the distribution pattern uniform.

  The gas concentration measurement method according to the second aspect of the present invention includes a detection region whose color changes according to the amount of gas exposure, a reference region having a color corresponding to at least two known exposure amounts, a detection region, and a reference region. A step of receiving input of image data obtained by photographing a gas exposure amount detection unit having a marker for specifying a position, and specifying a region corresponding to each of a detection region and a reference region by specifying the position of the marker in the image data A step of extracting color information at positions corresponding to the detection area and at least two reference areas from the image data, and evaluating the relative value by comparing the color information of the detection area with the color information of the reference area. And calculating a gas exposure amount by applying to a conversion formula.

  In the gas concentration measurement method, the method includes a step of setting relative coordinates in the image data based on the position of the marker in the image data, and the specifying step specifies the positions of the detection region and the reference region based on the relative coordinates. It is characterized by doing.

  In the gas concentration measurement method, the gas exposure amount detection means has a single color blank area around the detection area and the reference area, extracts the color information of the blank area from the image data, and is based on the color information of the blank area. And obtaining an illuminance distribution pattern of the image data, and performing image processing for making the distribution pattern uniform on the image data.

  In the gas concentration measuring method, the marker is arranged at an edge of the detection region and the reference region.

  In the above gas concentration measurement method, the difference between the step of storing the calculated gas exposure amount in the storage means and the gas exposure amount calculated this time by reading the gas exposure amount calculated last time from the storage means, Calculating a second gas exposure amount during the period.

  In the gas concentration measuring method, the step of storing the photographing time when the gas exposure amount detecting means is photographed in the storage means, the previous photographing time and the current photographing time are read from the memory means, the length of the period is obtained, And calculating an average gas concentration based on the amount of gas exposure and the length of the period.

  In the present invention, a detection region whose color changes according to the gas exposure amount, a reference region colored with at least two known gas exposure amounts, a detection region, and a position of the reference region are specified. By shooting the marker, extracting the color information for each of the detection area and reference area, evaluating the extracted color information with relative values, and applying the relative values to the conversion formula, It is possible to detect the amount of gas exposure while suppressing the influence of the above. Since a digital camera, a mobile phone with a camera, etc. can be used, a spectrophotometer is not required.

  In the present invention, by setting the relative coordinates based on the position of the marker in the image data, the detection area and the reference area can be specified in consideration of the shooting size, shooting angle, and image rotation. Photographers can use it without worrying about shooting.

  In the present invention, the color information of the blank area of the gas exposure amount detection means is extracted to obtain a distribution pattern of illuminance, and image processing is performed on the image data so that the distribution pattern is uniform, whereby the gradient is obtained. Can handle shadows and uneven color.

  In the present invention, the average concentration is obtained by taking the difference between the exposure amount and time at the previous photographing and the data of the exposure amount and time at this time and dividing the amount exposed between the previous time and the current time by the elapsed time. Can be requested.

  Thus, according to the present invention, accurate gas concentration measurement can be simplified.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, the measurement of the ozone gas concentration will be described, but it is of course applicable to other gases.

  FIG. 1 is a block diagram showing a configuration of a gas concentration measurement system in the present embodiment. The gas concentration measuring system shown in the figure includes a gas concentration measuring device 10, an image input device 30, and a gas concentration detecting sheet 40. The gas concentration measuring device 10 and the image input device 30 are connected via the network 20. On the gas concentration detection sheet 40, detection paper 41, color samples 42, 43, 44, and markers 45A, 45B, 45C, 45D are arranged. The image input device 30 photographs the gas concentration detection sheet 40 and transmits the obtained electronic image data to the gas concentration measurement device 10 via the network 20. The gas concentration measurement apparatus 10 that has received the electronic image data analyzes the color change of the detection paper 41 and calculates the ozone exposure amount by comparing with the color samples 42, 43, and 44.

  As the image input device 30, a digital camera, a digital video camera, a camera-equipped mobile phone, a web camera, or the like that captures images electronically can be used. A scanner may be used. In general, since the spectral configuration of the irradiated light differs depending on the light source, the color information of the captured electronic image is significantly affected by the shooting environment. Since the color information in the electronic image of the photographed detection paper 41 is also affected by the photographing environment, it is difficult to obtain accurate color information of the detection paper 41. Therefore, the entire color concentration detection sheet 40 including the detection paper 41, the color samples 42, 43, and 44 and the markers 45A, 45B, 45C, and 45D is photographed by the image input device 30, thereby the original color samples 42, 43, and 44. The color exposure information and the color information of the photographed color samples 42, 43, and 44 can be used to know the influence of the photographing environment, and the ozone exposure amount can be calculated from the color information of the detection paper 41 in consideration of the influence of the photographing environment. The markers 45A, 45B, 45C, and 45D are used to specify the positions of the detection paper 41 and the color samples 42, 43, and 44 on the electronic image.

  In the present embodiment, the detection paper 41 using indigo carmine as an ozone detection dye is used. The detection paper 41 is blue when not in use, and has a low reflectance band near 620 nm. As the ozone gas is exposed, the reflectance of this band increases, and the color of the detection paper 41 also changes from blue to white. Looking at the logarithm of the reflectance, the change width is the largest in the vicinity of 620 nm. This variation is known to be proportional to the amount of ozone gas accumulated exposure. The reflectivity near 620 nm is initially low but increases as it is exposed to ozone and appears to change from blue to white to the naked eye.

  FIG. 2 is a block diagram showing the configuration of the gas concentration measuring apparatus 10. A gas concentration measuring apparatus 10 shown in the figure includes a network interface 11, an electronic image processing unit 12, and an output interface 13. The gas concentration measurement device 10 may be configured by a computer including an arithmetic processing device, a storage device, a memory, and the like, and the processing of each unit may be executed by a program. This program is stored in a storage device included in the gas concentration measuring device 10, and can be recorded on a recording medium such as a magnetic disk, an optical disk, or a semiconductor memory, or provided through a network. Details of each part will be described below.

  The network interface 11 receives input of electronic image data obtained by photographing the gas concentration detection sheet 40 via the network 20.

  The electronic image processing unit 12 includes a marker position specifying unit 121, an orientation detection unit 122, an illuminance correction processing unit 123, and a gas concentration calculation unit 124, and the detection paper 41 is captured in the input electronic image data. The detection area and the reference area where the color samples 42, 43 and 44 are photographed are specified, the influence of the photographing environment is corrected, and the ozone exposure amount is calculated.

  The output interface 13 is connected to a display means (not shown) such as a display, and outputs the calculated ozone exposure amount.

  Details of the electronic image processing unit 12 will be described below.

  The marker position specifying unit 121 specifies the positions of the markers 45A, 45B, 45C, and 45D in the input electronic image data. In this embodiment, as shown in FIG. 3, the markers 45 </ b> A, 45 </ b> B, 45 </ b> C are arranged as “◎” and the marker 45 </ b> D is arranged as “Δ”, and they are arranged at the four corners of the gas concentration detection sheet 40. The positions of the markers 45A, 45B, 45C, and 45D are specified by a model identification method as shown in Non-Patent Documents 1 and 2.

  The markers 45A, 45B, 45C, and 45D may use colors having a large color difference from the colors of the detection paper 41 and the color samples 42, 43, and 44 and intermediate colors thereof. In the present embodiment, since the detection paper 41 changes color from blue to white, the colors of the markers 45A, 45B, 45C, and 45D are red. The marker position specifying unit 121 can specify the positions of the markers 45A, 45B, 45C, and 45D by searching the electronic image data for locations where the RGB R value is high and the G and B values are low. Certainty can be increased by using it together with the marker extraction method by the above-described model identification method.

  The orientation detection unit 122 sets relative coordinates based on the specified positions of the markers 45A, 45B, 45C, and 45D on the electronic image data. Specifically, as shown in FIG. 3, the coordinates of the marker 45D are (0, 0), the coordinates of the marker 45C are (X, 0), the coordinates of the marker 45A are (0, Y), and the coordinates of the marker 45B are Relative coordinates are set as (X, Y). Then, the detection area 41A for obtaining the color information of the detection paper 41 is designated by relative coordinates (1 / 10X, 2 / 10Y) − (2 / 10X, 8 / 10Y). Similarly, the reference area for acquiring the color information of each of the color samples 42, 43, and 44 is also designated by relative coordinates. In this way, by specifying the area from which the color information is acquired by relative coordinates, as shown in FIGS. 4A and 4B, even when the input electronic image data is distorted or rotated. Thus, the positions of the detection paper 41 and the color samples 42, 43, and 44 can be accurately specified.

  The illuminance correction processing unit 123 analyzes the color information of the blank area around the gas concentration detection sheet 40 and corrects the illuminance non-uniformity in the electronic image data. For example, the electronic image data shown on the left side of FIG. 5A is gradually brighter from top to bottom, and the illuminance is uneven. Even in such a case, the illuminance correction processing unit 123 uses the blank area 40A of the gas concentration detection sheet 40 (the white portions outside the markers 45A, 45B, 45C, and 45D in the present embodiment) in the vertical direction. Color information is extracted by scanning in the horizontal direction, and a color information distribution pattern of the entire gas concentration detection sheet 40 as shown in FIG. 5B is obtained. Then, image processing for returning the distribution pattern to white is performed on the original electronic image data. Thereby, the nonuniformity of the illuminance in the electronic image data can be corrected. FIG. 6A shows another electronic image data that gradually becomes brighter from the lower left to the upper right. FIG. 6B shows a distribution pattern of color information calculated from FIG. Also in this case, image processing that makes the distribution pattern shown in FIG. 6B uniform is performed on the original electronic image data shown in FIG.

The gas concentration calculation unit 124 acquires color information in each of the detection area and the reference area specified by relative coordinates from the electronic image data whose illuminance is corrected, and compares the degree of color change of the detection area with the color information of the reference area. Evaluate by relative value, and calculate ozone exposure by applying this relative value to the conversion formula of ozone exposure. Specifically, the ratio of the difference between the color information in the detection area and the color information in one of the reference areas to the difference in color information between the two reference areas is obtained, and the difference between the known ozone exposure amounts in the two reference areas is obtained. The ozone exposure is calculated by multiplying the ratio. For example, the RGB value, which is the color information of the color sample 42 corresponding to the ozone exposure amount 0 ppbh, is (40, 120, 200), and the RGB value of the color sample 44 corresponding to the ozone exposure amount 800 ppbh is (200, 200, 200), and when the RGB value of the detection paper 41 discolored according to the ozone exposure amount is (160, 180, 200), the R value having the largest difference between pixels among RGB. Is used to calculate the ratio of the difference between the color sample 42 and the detection paper 41 to the difference between the color samples 42 and 44.
(160-40) / (200-40) = 0.75
It becomes. Since the difference in ozone exposure corresponding to the color samples 42 and 44 is 800 ppbh, the ozone exposure measured by the detection paper 41 is
800x0.75 = 600ppbh
Is calculated. As described above, the ozone exposure amount can be calculated by photographing the detection paper 41 whose ozone exposure amount is unknown simultaneously with at least two color samples whose ozone exposure amount is known. In the case of the detection paper 41 using indigo carmine, it has been confirmed that the actual ozone exposure is very well matched by using the above calculation method.

  Further, when the ozone concentration is measured visually, it has been necessary to replace the detection paper 41 once used. However, the calculated ozone exposure amount is stored in the storage device of the gas concentration measuring device 10 and the ozone of this time is measured. By taking the difference between the exposure amount and the previous ozone exposure amount, the ozone exposure amount between the previous time and this time can be obtained. As a result, the ozone exposure can be measured many times until the detection paper 41 is completely whitened.

  Furthermore, by storing the photographing time in the storage device of the gas concentration measuring device 10, the average ozone concentration from the previous photographing can be calculated. Specifically, when the ozone exposure amount calculated at a certain time A is 500 ppbh and the ozone exposure amount calculated at time B two hours after the time A is calculated as 700 ppbh, the ozone exposure amount for two hours is 200 ppbh. Therefore, the average ozone concentration between times A and B is 200/2 = 100 ppb.

  Next, the flow of processing for obtaining the exposure amount in the gas concentration measurement system will be described with reference to the drawings. FIG. 7 is a flowchart showing a flow of processing for obtaining the exposure amount of the gas concentration measurement system. In addition, after calculating | requiring exposure amount, the process which calculates | requires an average gas density | concentration with the difference and elapsed time with last time is as above-mentioned.

  First, the image input device 30 shoots the gas concentration detection sheet 40 so that the detection paper 41, the color samples 42, 43, and 44, the markers 45A, 45B, 45C, and 45D, and the blank area 40A that are measurement objects are included, The captured electronic image data is transmitted to the gas concentration measuring device 10 via the network 20. The network interface 11 receives the electronic image data and stores it in a storage device such as a memory (step S701).

  Subsequently, the marker position specifying unit 121 reads out the electronic image data, and specifies the positions of the markers 45A, 45B, 45C, and 45D by searching the electronic image data for the shape and color of the marker (step S702).

  Subsequently, the orientation detection unit 122 sets relative coordinates for the electronic image data based on the identified markers 45A, 45B, 45C, and 45D, and calculates the orientation (tilt) of the measurement target in the electronic image data ( Step S703).

  Subsequently, the illuminance correction processing unit 123 extracts pixels in the electronic image data corresponding to the blank area 40A in the vertical direction and the horizontal direction, and represents a distribution pattern representing the illuminance distribution of the entire gas concentration detection sheet 40 in the electronic image data. Is calculated (step S704).

  The illuminance correction processing unit 123 that has calculated the distribution pattern uses the distribution pattern to correct the electronic image data so that the illuminance distribution is uniform throughout the gas concentration detection sheet 40 (step S705).

  Subsequently, the gas concentration calculation unit 124 acquires the RGB values of the areas corresponding to the detection paper 41 and the color samples 42, 43, 44 of the corrected electronic image data (step S706). The RGB values to be acquired are obtained by statistically processing the RGB values of each region such as the average and the mode value of the RGB values of the pixels in each region.

  Then, the RGB values of the detection paper 41 are compared with the RGB values of the color samples 42, 43, 44, and the ozone exposure around the gas concentration detection sheet 40 is based on the known ozone exposure amount corresponding to the color samples 42, 43, 44. The amount is calculated (step S707).

  FIG. 8 is a diagram illustrating an example in which markers are attached to the corners of the detection paper and the color sample. The markers 45 shown in the figure are arranged at the four corners of the detection paper 41 and at the four corners of the color samples 42, 43, 44. A square part surrounded by each marker 45 becomes a detection area and a reference area. Even in this case, as shown in the figure, the X axis and the Y axis that determine relative coordinates for designating each region are set on the captured electronic image data.

  FIG. 9 is a diagram showing an example using the gas concentration measurement system in the present embodiment. A server is installed on the network 20 and used as the gas concentration measuring device 10. The server has functions of a database server, a web server, and an image processing server.

  On the other hand, the user who measures the ozone concentration uses the scanner 30A, the digital camera 30B, or the web camera 30C to shoot the gas concentration detection sheet 40 on which detection paper or the like is arranged, and shoots using the personal computer 31 connected to the network 20. The uploaded electronic image data is uploaded to the gas concentration measuring apparatus 10. When uploading the electronic image data, the personal computer 31 accesses the web server and inputs the user name and password to log in.

  The uploaded electronic image data is stored in a database for each user. The photographing time data recorded in the header portion of the electronic image data is also recorded in the database.

  The gas concentration measuring device 10 processes the stored electronic image data to calculate the ozone exposure amount. When another electronic image data is sent, the average ozone concentration is calculated based on the ozone exposure amount calculated from the previous electronic image data and the interval of the photographing time. By registering the measurement location, the data for each measurement location may be distinguished and recorded in the database.

  The calculated ozone concentration may be displayed in a graph on the website 50 connected to the network 20. The user may have a function of downloading the calculated ozone concentration from the database.

  In addition, by using the personal computer 31 connected to the web camera 30C, electronic image data is acquired at regular intervals and uploaded to the gas concentration measuring device 10, thereby enabling real-time continuous measurement without an attendant.

  Furthermore, electronic image data may be attached to an e-mail and transmitted to the gas concentration measuring apparatus 10 using the camera-equipped mobile phone 30D. The ozone concentration calculated by the gas concentration measuring device 10 can be immediately received by mail.

  FIG. 10 is a diagram showing another example using the gas concentration measurement system in the present embodiment. As shown in the figure, a personal computer may be executed as a gas concentration measuring device 10 to input electronic image data without going through a network.

  As described above, according to the present embodiment, the gas in which the detection paper 41 that changes color according to the ozone exposure amount and the color samples 42, 43, and 44 that have colors corresponding to the known ozone exposure amount are arranged. The density detection sheet 40 is photographed by the image input device 30, and the gas concentration measurement device 10 compares the color information of the detection paper 41 with the color information of the color samples 42, 43, and 44, and calculates the ozone concentration. The ozone concentration can be measured without using a large and expensive apparatus.

  According to the present embodiment, the markers 45A, 45B, 45C, and 45D are arranged on the gas concentration detection sheet 40, and the electronic image data obtained by photographing the gas concentration detection sheet 40 is based on the markers 45A, 45B, 45C, and 45D. By setting the relative coordinates, the electronic image data can be analyzed in consideration of the photographing size, the photographing angle, and the rotation of the image, so that the photographer can use it without worrying about photographing. Further, the color information of the blank area of the gas concentration detection sheet 40 is extracted to obtain a distribution pattern of illuminance, and image processing is performed on the electronic image data so that the distribution pattern is uniform, thereby providing a shaded shadow. It can also handle uneven color.

It is a block diagram which shows the structure of the gas concentration measurement system in one embodiment. It is a block diagram which shows the structure of the gas concentration measuring apparatus in the said gas concentration measuring system. It is a figure which shows a mode that the relative coordinate was set to electronic image data. It is a figure which shows a mode that the relative coordinate was set to the distorted electronic image data. It is a figure which shows a mode that the distribution pattern of illumination intensity is extracted from electronic image data. It is a figure which shows a mode that the distribution pattern of illumination intensity is extracted from another electronic image data. It is a flowchart which shows the flow of the process which calculates | requires the exposure amount of the said gas concentration measurement system. It is a figure which shows the gas concentration detection sheet | seat which has arrange | positioned the marker to the edge of a detection area and a reference area. It is the schematic which shows the example which applied the said gas concentration measurement system. It is the schematic which shows another example to which the said gas concentration measurement system is applied. It is a figure which shows the conventional ozone concentration measuring device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Gas concentration measuring apparatus 11 ... Network interface 12 ... Electronic image processing part 121 ... Marker position specific part 122 ... Orientation detection part 123 ... Illuminance correction processing part 124 ... Gas concentration calculation part 13 ... Output interface 20 ... Network 30 ... Image input Apparatus 31 ... Personal computer 40 ... Gas concentration detection sheet 40A ... Blank area 41 ... Detection paper 41A ... Detection area 42, 43, 44 ... Color sample 45, 45A, 45B, 45C, 45D ... Marker 100 ... Ozone concentration measuring instrument 111 ... Mount 112 ... Detection paper 113, 114, 115 ... Color sample

Claims (9)

A gas exposure amount having a detection region whose color changes according to the gas exposure amount, a reference region having a color corresponding to at least two known exposure amounts, and a marker for specifying the position of the detection region and the reference region Detection means;
Input means for receiving input of image data obtained by photographing the gas exposure amount detection means;
Area specifying means for specifying an area corresponding to each of the detection area and the reference area by specifying the position of the marker in the image data;
Extraction means for extracting color information at positions corresponding to the detection area and at least two of the reference areas from the image data;
A calculation means for evaluating the color information of the detection area by a relative value compared with the color information of the reference area, and calculating the gas exposure amount by applying the relative value to a conversion formula;
A gas concentration measurement system comprising: Orientation detecting means for setting relative coordinates in the image data based on the position of the marker in the image data;
The gas concentration measurement system according to claim 1, wherein the region specifying unit specifies positions of the detection region and the reference region based on the relative coordinates. The gas exposure amount detection means has a single color margin area around the detection area and the reference area,
Illuminance for extracting color information of the margin area from the image data, obtaining an illuminance distribution pattern of the image data based on the color information of the margin area, and subjecting the image data to image processing for equalizing the distribution pattern The gas concentration measurement system according to claim 1, further comprising a correction unit. A gas exposure amount having a detection region whose color changes according to the gas exposure amount, a reference region having a color corresponding to at least two known exposure amounts, and a marker for specifying the position of the detection region and the reference region Receiving an input of image data obtained by photographing the detecting means;
Identifying a region corresponding to each of the detection region and the reference region by identifying the position of the marker in the image data;
Extracting color information of positions corresponding to the detection area and the at least two reference areas from the image data;
Evaluating the color information of the detection area by a relative value compared with the color information of the reference area, and calculating the gas exposure amount by applying the relative value to a conversion formula;
A gas concentration measuring method comprising: Setting relative coordinates in the image data based on the position of the marker in the image data,
5. The gas concentration measuring method according to claim 4, wherein the specifying step specifies the positions of the detection region and the reference region based on the relative coordinates. The gas exposure amount detection means has a single color margin area around the detection area and the reference area,
Extracting color information of the margin area from the image data, obtaining an illuminance distribution pattern of the image data based on the color information of the margin area, and subjecting the image data to image processing for uniformizing the distribution pattern The gas concentration measuring method according to claim 4 or 5, characterized by comprising:   The gas concentration measuring method according to claim 4, wherein the marker is arranged at an edge of the detection region and the reference region. Storing the calculated gas exposure amount in a storage means;
A step of reading the gas exposure amount calculated last time from the storage means, taking a difference from the gas exposure amount calculated this time, and calculating a second gas exposure amount in a period from the previous time to the current time;
The gas concentration measuring method according to claim 4, wherein: Storing in the storage means the photographing time when the gas exposure amount detecting means is photographed;
Reading the previous imaging time and the current imaging time from the storage means to determine the length of the period, and calculating an average gas concentration based on the second gas exposure amount and the length of the period;
The gas concentration measuring method according to claim 8, comprising: