1. A method of using a scanning microscope to rapidly form an image of a specimen, comprising: performing an initial scan or set of scans of a first area composed of a first set of pixels to determine a first gray level for each of the pixels in the first set; analyzing the first gray levels of the pixels in the first set to identify first regions representing structures of interest in said area, said first regions including fewer pixels than the number of pixels in the first set; and performing additional scans of said regions to determine second gray level values of only pixels of said regions, the second gray level values being determined by integrating more scans than the number of scans used to determine the first gray levels, thereby improving the accuracy of the measured gray level value of pixels in the regions while including fewer pixels in the additional scans.