HydroColor: Water Quality App is a tools app developed by Thomas Leeuw.
Download Statistics
HydroColor: Water Quality App has been downloaded 10 thousand times. In the last 30 days, the app was downloaded 73 times.
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App Information
HydroColor: Water Quality App is FREE to download. The APK download size is 64.68 MB. The latest version available is 2.4. The last update was on February 2, 2025.
Technical Requirements
HydroColor: Water Quality App requires Android 5.0+ or higher. The app has a content rating of Everyone. The app has been available on Google Play January 2015.
Description
HydroColor is a water quality application that uses the a smartphone's digital camera to determine the reflectance of natural water bodies. Using this information, HydroColor can estimate water turbidity (0-80 NTU), concentration of suspended particulate matter (SPM) (g/m^3) and the backscattering coefficient in the red (1/m). IMPORTANT: HydroColor requires the use of an 18% photographers gray card as a reference. Gray cards are widely available at photography shops and online. Visit the supporting website for more information on gray cards.
HydroColor has an easy to use interface that guides users through the collection of three images: a gray card image, a sky image, and a water image. To ensure the best results, HydroColor taps into the device's GPS, gyroscope, and compass to aid users in the collection of these images. After images are collected they can be analyzed immediately. In the analysis of the images, HydroColor calculates the reflectance of the water body in the RGB color channels of the camera. It then uses the reflectance values to determine the turbidity of the water in NTU (nephelometric turbidity units).
The data is instantly saved and can be accessed again via HydroColor or downloaded onto a computer from HydroColor's data folder. The text file contains additional information about the measurement including: latitude, longitude, date, time, sun zenith, sun azimuth, phone heading, phone pitch, exposure values, RGB reflectance, and turbidity.
How it works:
HydroColor uses the camera as simple light sensor (photometer). Relative light intensity can be measured by normalizing the camera pixel values by the exposure. Therefore, the three color channels of the camera (RGB: Red, Green, Blue) provide a measure of light intensity in three regions of the visible spectrum.
The light intensity measured in the water image is corrected for sky reflection off the surface (using the sky image). The corrected water image provides the intensity and color of light emanating from the water. This is normalized by the ambient illumination using the gray card image. The final product is a nearly illumination independent measure of the water’s reflectance, known as remote sensing reflectance. In oceanography, satellites are used to calculate the same product (remote sensing reflectance) from space.
The reflectance is directly related to the amount and type of suspended particles in the water. An increase in turbidly (i.e. suspended sediments) will cause greater scattering of light and increase the overall reflectance of the water. Particles containing pigments, such as phytoplankton (algae), will absorb light in specific regions of the visible spectrum. Thus, pigment containing particles can be detected by comparing the relative reflectance in the RGB channels.
The method HydroColor uses to measure reflectance has been published in the peer-reviewed journal Sensors and is freely available online (note: HydroColor has been updated to use RAW data from the camera sensor since this publication):
Leeuw, T.; Boss, E. The HydroColor App: Above Water Measurements of Remote Sensing Reflectance and Turbidity Using a Smartphone Camera. Sensors 2018, 18, 256. https://doi.org/10.3390/s18010256.
Recent changes: Back-end updates to use the latest APIs and frameworks.
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Comments on HydroColor: Water Quality App for Android
★★★★☆vijaykumar math· Oct 7, 2020
I request to have an inbuilt image of very card with 18 % reflectance The response after taking the photos is quite fast Vijaykumar N Math B E Electrical Ex IRS EE Ex MISTE
★★★★★A Google User· Jan 23, 2015
Awesome Every time I walk by the ocean, I wonder, what is the concentration of suspended particles. Now, I wonder no more. With this app, on daily basis I know how muddy the ocean is.
★★★★★Harpreet singh· Jun 19, 2020
Nice application, the data holds with real time images depicting environmental conditions as well as the turbidity which is important parameter for aquatic life. May research for color, pH (again after treating with coloring reagent), other universal parameters based on calorimetry.
★★★★☆Rashid Abdul Rahim· Oct 14, 2015
Cannot take a picture for sky n water I can't capture for sky n water picture...seem like not working with my android phone...my phone is galaxy nexus I9250 4.3 and the tilt line also does not appear. Hoping that I can use this awesome app. Please...help me
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