MATLAB code for analysis of RGB images: to Measure Chlorophyll a Fluorescence with Smartphones

MATLAB code for analysis of RGB images: to Measure Chlorophyll a Fluorescence with Smartphones

This new MATLAB algorithm serves to analyse red-green-blue (RGB) images, specifically taken by camera systems of smartphones.

The presented code uses the red band of a smartphone camera image to measure chlorophyll a fluorescence in a water sample. It was used and described in a SmartFluo system, developed for affordable measurements of water constituents.

Based on RGB images and the illumination time (exposure time) of a water sample in a cuvette by an external light source, the intensity of the red channel is calculated in a selected image fraction – a square around the midpoint of the image, automatically selected within the code. The script uses reference RGB images (blanks) for base line correction. RGB images used as reference are taken of reference solutions such as ultra-pure water or 90%-acetone. Sample RGB images are taken of a chlorophyll-a dilution series ranging from 1-250 µg L^-1.

Besides the code itself, also one reference RGB image and five sample RGB images for test purposes are provided. All provided images are taken by Samsung Galaxy S3 mini smartphone camera (Samsung, Seoul, Korea)

Short instructions to use the code are given in the "README.pdf". The algorithm was used in a publication that contains the original equations as well as the theoretical background of assumptions used for calculations.