A routine display fix on a 1987 Macintosh mutated into an unwieldy codebase. Industry doors shut. Then a single meeting at Adobe altered software history. Thomas Knoll wasn’t trying to build the world’s most influential image editor. In 1987, the University of Michigan PhD student had a narrower headache. His Macintosh Plus displayed images in black and white only, no grayscale, which made his computer... [4943 chars]