ExTrack annotates and refines single-molecule positions and extracts state-duration distributions. (a and b) Example tracks from simulations of immobile and diffusive ( = 2) molecules with symmetric transition rates of 0.1 Δt−1 with short tracks of 10 positions (a) or long tracks of 25 positions (b). Top: real positions with states in colors; bottom: noisy positions with probabilities (color bar), right: state probabilities along time. (c) Distribution of the probability to be diffusive at the time points where the particles are actually diffusive. Similar simulations than in panel a for different d*. (d and e) Position refinement module: Examples of two-state track (d) and three-state track (e). From left to right: Observed track and associated states probabilities; refined positions (colored) and observed positions in gray; probability density map of the consecutive positions. Top right: State probabilities as a function of time. Bottom right: SD of the probability density of refined positions. Simulation parameters: = 0, = 5, = = 0.1 Δt−1 (d); = 0, = 1.5, = 5, all k = 0.05 Δt−1 (e). (f) Histogram module: State-duration histograms of tracks of at least 21 positions for the indicated two-state model. Dashed lines: Distributions from ground truth. (g) Same as f for three-state tracks with two immobile states. Left: ExTrack fit assuming a two-state model; Right: ExTrack fit assuming a three-state model.
