Images from computers

Modern digital computers, in conjunction with microfilm plotters, are capable of generating a wide variety of images. Beyond the mere plotting of curves, graphs, and labels, special programming techniques can produce halftone renditions of pictorial material with wide applications in optical signal processing and data portrayal. Other possibilities include the composition of images from alphanumeric characters, the generation of moiré patterns, and the encryption of images with subsequent recovery by optical means using computer-generated ``keys.'' More sophisticated techniques allow the combining in a single optical display of different kinds of information in hitherto unforeseen ways.