The source parameters for each source in the product source-list file for the image (produced by omdetect) are loaded into memory. Any source with either a source-extension flag of 1, a confusion flag greater than zero, a significance no less than the value specified by the parameter minsignificance and no greater than than the value specified by the parameter maxsignificance and not less than a distance of 14 unbinned pixels from the edge of an image is discarded.
The list of useable sources is then looped through and for each one the mean counts in an circle of given radius is computed and the mean backghround subtracted using an annulus region. The list of background-subtracted counts versus radius is normalized to unity at a radius of zero.
A list of background-subtracted counts versus radius from the centre of the source is thus produced.