TWAIN is an interface that is used to easily import data from imaging devices, such as scanners. The plug-in connects with TWAIN-compatible devices that are installed on your computer.
The TWAIN plug-in update includes fixes for multiple document scanning and a crasher when attempting a second scan.
To install download the TWAIN plug-in update, double click .dmg to mount it, open mounted image, drag and drop (or copy and paste) TWAIN.plugin to Applications\Adobe Photoshop CS5\Plug-ins\Import-Export and relaunch PS.