1. A method of assisting a human observer to screen a cytological specimen, said method comprising, in combination: acquiring into a machine a set of digital image data representing said specimen; said machine analyzing said digital image data and thereby identifying regions in said specimen containing diagnostically significant material, each of the regions that said machine determines to contain diagnostically significant material defining a screenable region, whereby, said machine may exclude from further analysis any region that said machine determines to not contain diagnostically significant cytological material; said machine generating a function defining, individually with respect to each screenable region, a speed for presentation of said screenable region to said human observer, wherein said speed for presentation of a screenable region to said human observer defines a scanning speed for movement of said cytological specimen in relation to a microscope lens for displaying said region via a microscope to said human observer, and wherein said speed is slower for a screenable region that contains a greater quantity of diagnostically significant cytological material than another screenable region and said speed is faster for a screenable region that contains a lesser quantity of diagnostically significant cytological material than another screenable region; and said machine employing said function to control presentation of said screenable regions to said human observer, whereby said function may give a human observer more time to view a screenable region containing a greater quantity of diagnostically significant cytological material, and vice versa.