2.2 Image classification
We used the software ilastik [9] to classify all image pixels as
either root hair, root or background. The software provides a user
interface to create training sets by manually labelling pixels according
to their class and to look interactively at the results. For the
classification, we used a random forest classifier with features
obtained from morphological filters (validation dataset: σ=0.3-10;
demonstration dataset: 0.3-50). In the validation dataset, each image
was trained and classified separately, while for the demonstration
dataset we classified each genotype separately using ten to eleven
images from the corresponding genotype.