1. A computer software product comprising a computer readable storage medium having fixed therein a sequence of computer instructions directing a computer system to detect whether a genetic abnormality is present in a fixed sample containing at least one target nucleic acid, the instructions directing steps of: receiving a digitized color image of the fixed sample, which has been subjected to fluorescence in situ hybridization under conditions to specifically hybridize a fluorophor-labeled probe to the target nucleic acid; processing the color image in a computer to separate objects of interest from background; measuring size and color parameters of the revised objects of interest so as to identify and enumerate objects having specific predetermined characteristics associated with the target nucleic acid; and analyzing the enumeration of objects with respect to a statistically expected enumeration to detect whether the genetic abnormality is present wherein the step of processing comprises the steps of: passing the color image through a hole filling filter; passing the filled color image through an erosion filter; operating on the eroded filled color image to define outlines around areas; selecting pixels within the outlines by performing a logical NOT operation; and performing a logical AND operation between the selected pixels and the filled color image.