Photoshop was developed by two brothers, John Knoll and Thomas Knoll, in 1987. At the time, Thomas Knoll studied engineering at the University of Michigan and also took an interest in photography. Thomas’s father, Glen Knoll, was a photographer himself and even had a darkroom in his basement.
With his engineering skills and his inclination towards photography, Thomas managed to develop a script that allowed him to turn monochromatic images to grayscale on an Apple II Plus computer.
Thomas expanded this initial script with additional processes that made it possible to apply more effects to images on-screen.
During that time, Thomas’s brother John was a special effect designer at George Lucas’ Industrial Light and Magic. John joined his brother and together they created the first image editor. Image Pro was released in 1988.
Shortly after, Adobe bought the software and released the first version of Photoshop in February 1990. This is how Photoshop started.