A two-page guide by Ralph Griswold, part 3 of a series on making digital facsimiles of documents. It classifies printed material into text, line art, black-and-white (continuous tone) pictures, and color pictures, explaining monotone, multi-tone, continuous tone and halftone printing. Illustrations show line art, engraving, and magnified halftone dot patterns in black-and-white and color. The distinctions matter for choosing how to scan.