Microsoft KB Archive/192688

= PI: FAQ: The Purpose of TWAIN in Imaging =

Article ID: 192688

Article Last Modified on 6/12/2001

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APPLIES TO


 * Microsoft Picture It! 1.0 Standard Edition
 * Microsoft Picture It! 2.0 Standard Edition
 * Microsoft Picture It! 99 Standard Edition
 * Microsoft Publisher 2000 Standard Edition

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This article was previously published under Q192688



SUMMARY
TWAIN is the standard interface between software programs and image- capturing devices such as scanners and digital cameras. Nearly all scanners contain a TWAIN driver known as the Data Source, but only TWAIN- compatible software can use the technology. Digital cameras may or may not use TWAIN for downloading images.

Twain is an Application Programming Interface (API), meaning it communicates between software programs and image acquisition devices.

Some of TWAIN features included in Microsoft Products may not be supported by all scanners. Additionally, older data sources may or may not be fully compatible with the established 1.6 standard.



MORE INFORMATION
TWAIN provides a simple method for universally connecting TWAIN-compliant programs with TWAIN-aware devices. The model for how programs interact with the source of input data can be described through a four-layer protocol:


 * Picture It! (Application layer)
 * TWAIN.DLL or TWAIN_32.dll (Protocol layer or the Source Manager)
 * The Data Source (*.ds) (Acquisition layer or the Source)
 * Scanner or Digital Camera (Device layer)

Microsoft installs the first two components (the Application and the TWAIN Dll's) during Setup. The Data Source is installed by the software provided by the manufacturer and is shipped with the scanner or camera.

In order for the product to work with a TWAIN-aware device, there must be a Data Source for the device installed on the system. Without a Data Source, the Product will not recognize the device and you will not be able to access it from within Picture It!

