Cell-ID's volume measurement as a function of how circular the
cells are. The y-axis shows the ratio 4/3*piR^3 where R is such that
the area of the cell is piR^2, to the volume calculation implemented
in Cell-ID The x-axis shows a measurement of circularity described in
Gordon, et .al. 2007. The more circular cells appear to the left. As
cells become more and more irregular, the 4/3*piR^3 measurement
begins to overestimate the volume. Each point is a single cell, and
images from three sample cells are shown in the plot. Image from