Detection of clusters in population of cells. Grayscale images representing the distribution of cells at a particular timepoint in two chemotaxis model simulations. Clusters comprising at least 5 sufficiently close cells are automatically detected and outlined using different colours. Cells are represented as gray points if they do not belong to a cluster. Otherwise they are represented as coloured points such that the colour of the cell matches the colour of the cluster it is a member of. Each cluster is enclosed by a polygon whose shape (triangular, rectangular or circular) best matches the shape of the cluster. Similarly to Figure 1B cells aggregate in the centre where the concentration of chemical attractant is highest.