A strategy for using processed, digitized images of one-dimensional electrophoretic gels to facilitate the analysis of large sets of overlapping clones is described. The images are acquired from fluorescently stained gels or from transilluminated gel photographs using a cooled, solid-state charge-coupled device camera. By employing sets of bands in the size-standard lanes as reference points, all the gel images are spatially normalized to a common reference template. After normalization, lane images from different gels can be compared as though the gels had been electrophoresed resed under identical, uniform-field conditions. Applications of this procedure to the analysis of a large set of overlapping λ clones from chromosome VII of Saccharomyces cerevisiae and to the estimation of fragment sizes are illustrated.