The Computer History Museum presents the Software Gems series, spotlighting the source code history of revolutionary software. Focus is placed on Adobe Photoshop, which originated in 1987 when brothers Thomas and John Knoll developed an image editing program for personal use, not anticipating its commercial success. Over the years, Photoshop evolved and, with Adobe’s support, became a global phenomenon. The source code of the original 1990 version is now available for non-commercial use, providing insight into the software’s foundations. Software architect Grady Booch commends the code’s structure and complexity, underscoring the significance of studying and appreciating software source code as an integral part of computer science history.
https://computerhistory.org/blog/adobe-photoshop-source-code/