Bloomin' Algae vs ColourWorker

This app helps to identify and record blue-green algae which naturally occur in lakes, ponds, canals, rivers and reservoirs around the world. These can produce toxins that are harmful to the health of people and animals. These algae are most commonly seen during the summer months, particularly in calm warm conditions. The app also asks you for details of what activities you are carrying out in or around the water, as blue-green algal blooms pose a greater risk to water-based activities, such as swimming or windsurfing, compared to non-contact activities such as walking. By gathering details of activities undertaken we hope to gain a better understanding of how algal blooms are impacting recreational use of freshwaters in the UK.

In general it is not possible to make accurate colorimetric and spectral measurements in conventional photographic images for two main reasons. First because variation in illumination spectra cannot be discounted, and second because the number of degrees of freedom in reflectance spectra is potentially much greater than the three provided by camera RGB signals. Consequently, colorimetry requires either spectrometers or multi- and hyper-spectral imaging, which are costly and inconvenient. ColourWorker uses automatic calibration and statistical modelling to improve the accuracy of color measurement in photographic images. This app implements ColourWorker technology on iOS. It allows users to select application areas, to take a photograph with a calibration standard, and returns estimated an average L*a*b* colorimetric value and for pixels in a defined region of the image along with a plot of the reflectance spectrum.