The average color reference plate.

<p>This reference is computed by averaging over the detected reference plates from all images used in this study (see text for details). Colors are referring the RGB triplets (left to right) (181,185,100), (147,179,200), (146,173,106), (173,101,147), (183,67,80), and (69,88,154).</p

The correlation loading plot obtained after PLS-regression.

<p>It was computed with light (), flow rate (), amount of sediment (, ), and time () as predictors (blue dots), and HSV-variables (), relative size (), photosynthetic efficiency (<i>P</i>) and sediment coverage (<i>SC</i>) as responses (red dots). The outer circle represents 100% explained variance and the inner circle 50% explained variance for the different variables.</p

A simplified illustration of the impact quantification process.

<p>The process is starting on the upper left with the laboratory experiment, continuing with the image recording, the labeling by the experts, the application of the unsupervised machine learning algorithm (see Machine Learning section for details) and ending with the image segmentation and the measuring of size and color of the segmented area.</p

A screenshot of the BIIGLE system in a web-browser.

<p>The images of the calcareous algae were examined and labeled using the BIIGLE system. Images can also be zoomed to examine more details. The experts were allowed to select single point label or customizable frame labels. The single point labels are represented as filled colored circles, the customizable frame labels are represented as white outlined rectangles with a filled colored circle in the upper left corner of the individual rectangle. The colors of the filled circles indicate the class of the individual label. Red is representing “live” calcareous algae, yellow “stressed” calcareous algae, green “dead” calcareous algae and Pink “bare substratum”.</p

The relative position of the sample can have an effect on the segmentation result.

<p>Both images are displaying the same calcareous algae sample, but were recorded at different time points during the experiment. The calcareous algae sample was rotated around an axis not perpendicular to the image plane.</p

Illustration of color reference plate and camera setup.

<p>On the left the original color reference plate, used to obtain color constancy within the experiment, is displayed. Colors are referring to the RGB triplets (top-down): (0,0,255), (255,0,0), (255,0,255), (0,255,0), (0,255,255), (255,255,0). On the right a schematic layout of the underwater camera setup is presented, consisting of a water filled cylinder containing the sample, the color reference plate and the camera in the waterproof housing fixed on a tripod.</p

The correlation loading plot for the photosynthetic efficiency (<i>P</i>).

<p>It was obtained after PLS-regression with the HSV-variables () as predictors (blue dots), and photosynthetic efficiency (<i>P</i>) as response (red dot). The outer circle represents 100% explained variance and the inner circle 50% explained variance for the different variables. The plot showed that the predictor variables are highly correlated to the response variable. A prediction of the photosynthetic efficiency using the HSV-values is therefore possible for our experiment.</p

Goodness of fit and prediction of the PLS-regression.

<p>Goodness of fit and prediction of the PLS-regression.</p

Results for the evaluation of the segmentation.

<p>Results for the evaluation of the segmentation.</p

Example of one pair of calcareous algae samples.

<p>In the top row the original images recorded at T2, T5 and T9 are shown. In the middle row the segmentation results are highlighted and in the lower row the live calcareous algae relative size () and hue (), starting from 10 (slightly orange red) to 0 (red), are presented. The samples were exposed to (a partially covered sample), and .</p