The software was developed in 1987 by two brothers Thomas and John Knoll. Thomas Knoll, a student at the University of Michigan, began writing a program on his Macintosh Plus to display grayscale images on a monochrome display.
This program caught the attention of his brother John, an Industrial Light & Magic employee, who recommended that Thomas turn it into a full-fledged image editing program.
Thomas named his program Photoshop and worked out a short-term deal with scanner manufacturer Barneyscan to distribute copies of the program with a slide scanner; a “total of about 200 copies of Photoshop were shipped” this way.
John traveled to Silicon Valley and gave a demonstration of the program to engineers at Apple and Russell Brown, art director at Adobe.
Both showings were successful, and Adobe decided to purchase the license to distribute in September 1988.
Photoshop was initially only available on Macintosh. In 1993, Adobe chief architect Seetharaman Narayanan ported Photoshop to Microsoft Windows.