1. An imaging system with an enlarged depth of field for use with a means for focusing an image, said imaging system comprising: means for sensing an image sample from each of a plurality of portions of said image at each of a plurality of optical distances from said means for focusing, said means for sensing including means for scanning said image in a first direction, and a plurality of sensor means extending generally transverse to said first direction for sensing a line of image samples of said image at said plurality of optical distances; means for determining the relative focus of the image samples derived from a portion of said image at each of said plurality of optical distances; and means, responsive to said means for determining, for choosing, for each of said plurality of portions of said image, the image sample having a desired focus.