3.1 Validation
To validate our method we extracted root hairs in all fifteen images of the validation data set and compared the results to the manual measurements. As illustrated in Figure 2, the distributions of root hair length obtained with the automatic approach matches the distributions of manually extracted root hair in all fifteen images. The analysis of the results showed a strong correlation between automatic and manual results in mean root hair length (R 2=0.93,p <.001), maximum root hair length (R 2=0.90, p <.001) and number of root hairs (R 2=0.63,p <.001).