Overview of TWAIN

TWAIN defines a standard software protocol and application programming interface (API) for communication between software applications and image acquisition devices.

Users need a way to get image data into their applications. Software developers need compatibility with the widest range of output devices without writing and maintaining multiple device drivers.

The solution to this situation is an open industry interface (TWAIN) that directly acquires image data from external sources while within an application.

With this, each software developer supports a standard data acquisition manager and each hardware vendor writes one driver for their device. Hardware vendors benefit because they need only provide one standard driver for their device, which can then be used by all software applications supporting the TWAIN data acquisition interface.

Three Key Elements in TWAIN

The Application software — An application which has been written to use TWAIN.
The Data Source Manager software — The software which manages the interaction between the application and Data Source. This manager (TWAINDSM.dll) can be found at www.twain.org.
The Data Source software — The software which controls the image acquisition device which has been written to comply with the TWAIN specifications. It is generally supplied by the acquisition device manufacturer.

TWAIN defines how application developers can acquire image data directly into their application without requiring the user to switch out of the application. To provide this feature, TWAIN requires Data Sources to provide a built-in user interface (UI) for their device. Application developers can, if they choose, disable the built-in User Interface provided by the Data Source and provide their own User Interface to control TWAIN devices.

Support for disabling the built-in User Interface must be provided by the Data Source.