The installer for CS3 does not function correctly in macOS 10.14 (Mojave), though it is still possible to install it through Terminal commands launched under safe mode, or installing it on an older version, such as macOS 10.12 Sierra, and then upgrading. In December 2019, Adobe stopped providing CS3 downloads entirely. Registered users who wished to continue using Photoshop CS3 after that date could use their valid serial number to download a new installer from Adobe that could be activated without contacting a server. In July 2017, activation servers for CS3 applications were shut down.
Photoshop CS3 was the first version to be distributed in DVD format, and the last to support Windows Vista RTM and Mac OS X Leopard on PowerPC Macs.
ImageReady web export features built directly into Photoshop and no longer a separate application.More complete 32 bit / HDR support (layers, painting, more filters and adjustments).Alterations to Curves, Vanishing Point, Channel Mixer, Brightness and Contrast, and the Print dialog.Native support for the Intel-based Macintosh platform and improved support for Windows Vista.
