F-score values for Experiment 1 & 2 (alternative parameter settings). F-score (combined measure of recall and precision, calculated from the ground truth features) for dilution series of the seed and leaf extract (left-most and middle part) and for mixtures of the seed and leaf extract (right-most part of the figure). Detected features that match the respective ground truth features were counted als true positives, while all other features returned were considered as false positives. Higher F-score values represent better feature detection performance. Alternative parameter settings were used (see Additional file 4).