A few paragraphs from Steven Heller's obituary in The New York Times:
Mr. Weber invented a number of typographic and graphic techniques, but none was more popular than the one that made two-dimensional photographs seem to spring off the page. It was used frequently during the late 1960s by underground poster artists to give their artwork a psychedelic look.
Called posterization, the technique involved converting black-and-white or color photographs into a series of three separate negatives, each designated for a different color. They were then printed together, each slightly off register. The resulting images appeared to be multidimensional. (The effect cannot be shown in black and white.)
In 1942 Mr. Weber invented and patented a photographic device that could change the appearance of gothic lettering by, among other things, expanding, compressing or ballooning it. The device helped to start a trend in special-effects lettering.
Another of his signature methods took continuous-tone photographs — including portraits and product images — and converted them into fine-line renderings, making them appear as pen-and-ink drawings or engravings. These and other techniques were known together as the Weber Process.