Water turbidity measuring device and method

Abstract

The invention provides a water quality turbidity measuring device and method, and belongs to the field of water quality detection.The measuring device comprises an umbilical tube, a camera, an artificial light source and a shade guide and is used for measuring turbidity and correcting color cast of an underwater image based on the white balance theory after the transmissivity is calculated. The measuring method comprises the following steps: the measuring device acquires a reference image and an underwater image, and respectively calculates the average brightness of a white block area; and calculating the water turbidity based on the average brightness of the white block area. The device disclosed by the invention does not need to use an additional turbidimeter, is adaptive to various navigation equipment and use scenes, and realizes efficient and convenient measurement of the water turbidity.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of water quality detection, and particularly relates to a water quality turbidity measuring device and method. BACKGROUND

[0002] Water quality standards are constantly developing and improving, and at the same time, the corresponding water quality detection technology and detection level are also constantly improving. Water resources are closely related to human beings, and the quality of water will directly affect the development and progress of human society. The marine ranching is an important part of marine fishery resources, and the water quality directly affects the survival and reproduction of marine organisms, and further relates to the sustainable use of fishery resources, so it is of great significance to predict the water quality parameters in the marine ranching.

[0003] Turbidity refers to the degree of obstruction of a light beam passing through a solution to be measured, and is a measure of the reduction in liquid transparency caused by the presence of substances in water that scatter light. It is an important parameter for representing water quality. Monitoring the turbidity in the net cage can not only predict the changes in water quality in real time, but also monitor the breeding environment of water production, and predict the remaining condition of bait through turbidity during artificial feeding, so as to realize real-time bait feeding and more scientific and accurate marine crop breeding. Turbid water directly affects human entertainment and water safety, and has a negative impact on the overall value of water. The size of turbidity is inversely proportional to the quality of water, and reducing turbidity is beneficial to improving water quality and reducing the content of harmful substances such as bacteria and viruses in water. Therefore, water turbidity detection is particularly important and has important significance for environmental protection and human health and safety.

[0004] The turbidimeter is a common method for measuring turbidity at present, but the turbidimeter measurement method needs to set up a turbidimeter separately, which introduces additional cost and device, and the existing turbidimeter method has difficulty in sampling at the water depth under water, and is not convenient for measurement. The measurement result will be affected by the sample, and if the sample is not uniform, the measurement result will be greatly deviated. SUMMARY

[0005] In order to solve the problem of the prior art in underwater turbidity measurement, the present application provides a water turbidity measuring device and method.

[0006] In order to achieve the above purpose, the present application provides the following technical scheme: A water turbidity measuring device, comprising: An umbilical cord pipe, the upper end of which is arranged at the bottom of a water carrier, and a branch support extends from the umbilical cord pipe; A camera arranged at the lower end of the umbilical cord pipe; An artificial light source arranged on the umbilical cord pipe above the camera; A colorimetric plate arranged on the branch support opposite to the camera.

[0007] Preferably, the color chart is movable on the branch support for adjusting the distance between the color chart and the umbilical tube and the height of the color chart.

[0008] Preferably, the method comprises the following steps: acquiring a color chart image as a reference image by a camera in a dark indoor place, and calculating the average brightness of a reference white block region based on the reference image; placing a water quality turbidity measuring device in a water area to be detected, acquiring a color chart under irradiation of an underwater artificial light source by a camera to obtain an underwater image, and calculating the average brightness of an underwater white block region based on the underwater image; calculating the water turbidity according to the average brightness of the reference white block region and the average brightness of the underwater white block region.

[0009] Preferably, the average brightness of the reference white block region is calculated based on the reference image, specifically, the image is converted from an RGB color space to an intermediate transition CIEXYZ color space, and then converted from the CIEXYZ color space to a CIELAB color space to calculate the average brightness of the reference white block region.

[0010] Preferably, the method further comprises calculating the transmittance of each color channel according to the reference image and the underwater image, and adjusting the white balance of a camera CCD photosensitive element, specifically, calculating the color mean value of a red block, a green block and a blue block based on the reference image; filtering the pixels of the red block, the green block and the blue block of the underwater image to remove abnormal values, calculating the average color value of the pixels of each region after filtering; calculating the transmittance of each color channel based on the color mean value and the average color value of each block, and adjusting the white balance of the underwater camera based on the transmittance of each color channel.

[0011] Preferably, the transmittance of each color channel is calculated based on the color mean value and the average color value of each block, specifically through the following formula: ; wherein c refers to the R, G and B color channels, is the average color value, is the color mean value, is the background light intensity.

[0012] Preferably, the background light intensity is the background light intensity of three channels estimated by a dark channel prior method based on the underwater image.

[0013] Preferably, the water turbidity is calculated according to the average brightness of the reference white block region and the average brightness of the underwater white block region, specifically through the following formula: ; wherein L is the distance from the colorimetric plate to the camera, L is the distance from the colorimetric plate to the camera,

[0014] Preferably, it further comprises filtering the white blocks in the underwater image to remove outliers before calculating the average brightness of the underwater white block area.

[0015] The water quality turbidity measuring device and method provided by the application have the following beneficial effects: The water quality turbidity measuring device provided by the application is suitable for various navigation equipment and complex underwater lighting environments, has high scene applicability, and does not need to use a turbidimeter additionally. The underwater camera and artificial light source of the device are used to collect images of the underwater observation environment. The distortion-free images taken on land are used as a reference, the average brightness parameter is calculated based on the images, the turbidity is calculated through the average brightness, the accuracy and reliability are high, and the water quality turbidity can be obtained on site without sampling, which is beneficial to real-time monitoring of water quality changes and cost reduction. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the application and the design scheme thereof, the drawings required by the embodiments will be briefly introduced as follows. The drawings in the following description are only part of the embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings.

[0017] Figure 1 FIG. 1 is a structural schematic diagram of the water quality turbidity measuring device of the application.

[0018] Figure 2 FIG. 2 is a colorimetric plate schematic diagram in the embodiment of the application.

[0019] Figure 3 FIG. 3 is a principle diagram of the water quality turbidity measuring device in the embodiment of the application.

[0020] Figure 4 FIG. 4 is a flowchart of the water quality turbidity measuring method in the embodiment of the application. DETAILED DESCRIPTION

[0021] In order to make those skilled in the art better understand the technical scheme of the application and can be implemented, the application will be described in detail below in combination with the drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical scheme of the application, and cannot be used to limit the protection scope of the application.

[0022] EMBODIMENT The application provides a water quality turbidity measuring device, which comprises a colorimetric plate, an underwater camera, an artificial light source, and a processor. Figure 1As shown, including: umbilical tube, camera, artificial light source and color chart.

[0023] A umbilical tube is extended downward from the upper carrier (boat, aircraft, etc.), and a cable is passed through the tube, which has a fixing device, power supply and information transmission function; the camera is fixed at the end of the pipeline, responsible for collecting visible light images; a controllable artificial light source is arranged on the upper part of the camera, which can adjust the light intensity and other parameters; another section of the bracket is extended from the tube, and a special color chart is arranged on the bracket, the distance from the color chart to the pipeline is known and adjustable, and the height of the color chart to the bracket is adjustable. The color chart is shown in Figure 2 .

[0024] The turbidity measurement principle based on a water quality turbidity measurement device is shown in Figure 3 , specifically: (1) Use the color chart image taken on the shore as a reference for non-distorted image, and estimate the background light intensity, then calculate the transmittance of light of different color channels through the Jaffe-McGlamey classic model of underwater imaging, specifically through the following formula, and then adjust the white balance parameters of the camera CCD according to the proportion of attenuation of each color channel.

[0025] Among them: is the image taken by the camera, is the non-distorted target image (i.e. the image taken on the shore), x represents a specific pixel point; is the transmittance of light in channel c, which represents the absorption and reflection characteristics of the medium to light, is the red, green, and blue channels of the image; is the ambient light intensity. is the direct component of light propagation in water, is the backscattering component, which can be ignored due to its small influence on image degradation.

[0026] (2) The camera has three CCD light sensing components, each receiving red, green, and blue light. In the default state, the signal gain ratio of the three sensing units remains balanced, i.e. the amplification ratio of the three is equal, with a ratio of 1:1:1. The essence of white balance adjustment is to change the gain ratio of each channel according to the scene being adjusted to achieve color correction. For example, when the red, green, and blue light reflected by the object is in a ratio of 1:1:2 (blue light accounts for a large proportion, and the color temperature is high), adjust the white balance ratio to 2:2:1. After adjustment, the gain intensity of the blue channel is significantly reduced, while the amplification ratio of red and green is increased, so that the red, green, and blue proportions of the object image after white balance adjustment circuit are the same, and finally the energy distribution area of each primary color in the imaging picture is balanced.

[0027] If the calibrated white area appears blue, the white balance system will intelligently adjust the gain parameter: on the one hand, weaken the amplification coefficient of the blue channel, on the other hand, synchronously improve the gain value of the green and red channels. Through this dynamic compensation mechanism, even if the color temperature of the original light exists deviation, the final imaging can still accurately restore the real white color of the object. This electronic compensation process ensures the accuracy of color reproduction in different color temperature environments. By calculating the transmittance of each color channel, the proportion of red, green and blue light in the current imaging can be known, and by adjusting the gain of each color channel of the camera according to the concept of white balance adjustment, the purpose of eliminating imaging color deviation can be achieved.

[0028] (3) According to Lambert-Beer law, the turbidity of water body is measured by transmission light method. The luminous intensity of transmitted light is calculated by the following formula:

[0029] ; Wherein, represents the luminous intensity of transmitted light, represents the luminous intensity of incident light, K is a proportional constant, T represents turbidity, and L represents the transmission path of light, that is, the depth of liquid transmission.

[0030] According to Lambert-Beer law, the method for calculating the turbidity of water body by transmission light method can be obtained: ; Wherein, , represents the transmittance of light intensity of water body.

[0031] The present application provides a water quality turbidity measurement method, as shown in Figure 4 , specifically comprising the following steps: S1: initially, in a room without light, use the light source carried by the device as the only light source, and shoot the color chart as a distortion-free reference image. And collect and record the average color value of the red, green and blue blocks in the image and calculate the average brightness of the white block area. When calculating the brightness, the image is converted from RGB color space to CIELAB color space for calculation. Since RGB cannot be directly converted to CIELAB, CIEXYZ color space is used as an intermediate transition. The L component of CIELAB color space is the brightness, which represents the light intensity.

[0032] The transformation from RGB to CIEXYZ is: ; The conversion from CIEXYZ to CIELAB is: ; Wherein: L represents brightness, a is green-red color component, and b is blue-yellow color component, , , The X, Y, and Z values ​​for the standard reference white point are 95.047, 100.0, and 108.883, respectively.

[0033] .

[0034] S2: Place a water turbidity measuring device underwater at the test site, turn on the device's built-in light source output, and take a picture of the colorimetric plate in the water.

[0035] S3: After filtering outliers from the white areas in the obtained underwater image, calculate the average brightness of the pixels in the white area, denoted as . ; Calculate the average brightness of the white area in the reference image obtained on land, and denote it as... Given that the distance from the colorimeter to the camera is L, the current turbidity of the water body can be obtained from the Lambert-Beer law as: .

[0036] S4: Underwater images are affected by turbidity, an effect reflected in color information. The clearer the water, the closer the underwater colors are to those on land, and the higher the transmittance. Therefore, after measuring turbidity, the transmittance of each color channel is calculated to adjust the white balance of the camera's CCD sensor, eliminating color cast and obtaining an underwater image closer to human vision. Specifically:

[0037] S41: Estimate the background light intensity of underwater images using dark channel priors, from the dark channel of the image. Select the brightest 0.1% of points in the image, and find the corresponding points in the original image as estimates for background light B. Find the background light intensity in each of the three channels. , , .

[0038] S42: The colors of the color chart are known prior information. Based on the distortion-free reference image obtained in S1, the color mean of the red, green, and blue blocks in the distortion-free image is calculated respectively, denoted as... , , After filtering outliers from the red, green, and blue regions of the underwater image, the average color value of each region is then taken as the mean. , , The transmittance of each color channel was calculated as follows:

[0039] ; Where c refers to the R, G, and B color channels, and C in the formula represents the parameters of the R, G, and B channels respectively.

[0040] S43: Adjusting white balance to fix the color cast of underwater images. The average value of the three-channel transmittance is , , The ratio of red, green and blue light in the underwater image taken by the current camera is According to the concept of white balance, the gain ratio of red, green and blue light is adjusted to , so that the ratio of red, green and blue in the image formed by the camera after white balance adjustment is balanced, and the underwater image taken by the camera is more consistent with the visual perception of the human eye.

[0041] It should be noted that the above specific embodiments can enable those skilled in the art to more fully understand the present invention, but in no way limit the present invention. Therefore, although the present invention has been described in detail in the present specification and examples, those skilled in the art should understand that the present invention can still be modified or equivalently replaced; and all technical solutions and improvements that do not deviate from the spirit and scope of the present invention are covered by the protection scope of the present invention. Any reference signs in the claims should not be considered as limiting the claims involved. Any simple changes or equivalent replacements of technical solutions that can be obviously obtained by those skilled in the art within the technical scope disclosed by the present invention belong to the protection scope of the present invention.

Claims

1. A water quality turbidity measuring device, characterized by, The application relates to a water quality turbidity measuring device, comprising the following parts: An umbilical tube, the upper end of which is arranged on the bottom of a water vehicle, and a branch support extending from the umbilical tube; A camera arranged at the lower end of the umbilical tube; An artificial light source arranged on the umbilical tube and above the camera; A color plate arranged on the branch support and opposite to the camera.

2. The water quality turbidity measuring device according to claim 1, wherein The color plate can move on the branch support, so as to adjust the distance between the color plate and the umbilical tube and the height of the color plate.

3. A water turbidity measuring method for the water turbidity measuring apparatus according to claim 1, characterized by, The application further relates to a water quality turbidity measuring method, comprising the following steps: An image of the color plate is collected by the camera in a dark indoor environment as a reference image, and the average brightness of a reference white block region is calculated based on the reference image; The water quality turbidity measuring device is placed in a water area to be detected, and an underwater image of the color plate irradiated by the artificial light source is collected by the camera; the average brightness of an underwater white block region is calculated based on the underwater image; The water turbidity is calculated based on the average brightness of the reference white block region and the average brightness of the underwater white block region.

4. The method of claim 3, wherein, The average brightness of the reference white block region is calculated based on the reference image, specifically, the image is converted from an RGB color space to an intermediate CIEXYZ color space, and then converted from the CIEXYZ color space to a CIELAB color space, so as to calculate the average brightness of the reference white block region.

5. The method of claim 3, wherein, The transmission rate of each color channel is calculated based on the reference image and the underwater image, so as to adjust the white balance of the CCD photosensitive element of the camera, specifically, the color average values of red blocks, green blocks and blue blocks are calculated based on the reference image; The pixels of the red blocks, the green blocks and the blue blocks of the underwater image are filtered to remove abnormal values, and the average color values of the pixels of each region after filtering are calculated; The transmission rate of each color channel is calculated based on the color average values and the average color values, and the white balance of the underwater camera is adjusted based on the transmission rate of each color channel.

6. The method of claim 5, wherein, The transmission rate of each color channel is calculated based on the color average values and the average color values, specifically through the following formula: ； where c refers to the R, G and B color channels, is the average color value, is the color mean value, is the background light intensity.

7. The method of claim 6, wherein the step of measuring the turbidity of the water is performed by a nephelometric method. The background light intensity is estimated by using a dark channel prior method to obtain the background light intensity of three channels based on the underwater image.

8. The method of claim 3, wherein the step of measuring the turbidity of the water is performed by a nephelometric method. The water turbidity is calculated based on the average brightness of the reference white block region and the average brightness of the underwater white block region, specifically through the following formula: ； wherein, L is the distance of the color chart to the camera, L is the distance of the color chart to the camera, 9. The method of claim 3, wherein, The white blocks in the underwater image are filtered to remove abnormal values before the average brightness of the underwater white block region is calculated.

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