Mapping of the diseased areas segmented using the three thresholding approaches. Two weeks-old bean plants cv. Flavert were inoculated with either Xff CFBP4834-R (1.106 CFU ml_1) or mock. This leaflet inoculated with Xff CFBP4834-R was sampled on bean cv. Flavert at 11 dai. A: visible image obtained by scanning. B: Fv/Fm image obtained by chlorophyll fluorescence imaging. C-E: Segmentation of the Fv/Fm image for selection of the diseased area. C: Expert-based thresholds are defined after comparison with visual observations by trained raters. D: Model-based thresholds are defined by the clustering approach on the total surface af the leaflet. E: Probability-based thresholds are defined on the probability that a healthy pixel is misclassified with a specificity of 0.002. The healthy tissues are represented in white. The diseased tissues are colored in red, blue or green. Defioliation spots are represented in black.