Flowchart illustrating the visual identification of edges. An example of a galaxy, SDSS J003143.28+005402.4, and its profiles with the identified edge (vertical dotted line) is shown in the top right side of the flowchart. If the galaxy is symmetric, the relevant parameters in the edge, namely, R_edge, the colour and mass density at the edge are saved. However, if the galaxy contains any non-symmetric features such as tidal streams in its outskirts such as the example SDSS J012859.56−003342.96 shown in the lower section of the flowchart, they are masked and the process of finding the edge is attempted once again. No edges are reported for cases when even an improvement in the masking did not present an edge. See Sect. 5.1 for details.