Windows Image Acquisition

Windows Image Acquisition (WIA) is a driver model and application programming interface (API) for modern Microsoft Windows operating systems that enables graphics software to communicate with imaging hardware such as scanners, digital cameras and Digital Video-equipment. It was first introduced in 2000 as part of Windows Me, and continues to be the standard imaging device and API model through successive Windows versions. It is implemented as an on-demand service in Windows XP and later Windows operating systems.

Overview

WIA is a significant super-set of the support for digital still imaging that was provided by the Still Image Architecture (STI) in Windows 98. Whereas STI only provided a low-level interface for doing basic transfers of data to and from the device (as well as the invocation of an image scan process on the Windows machine through the external device), WIA provides a framework through which a device can present its unique capabilities to the operating system, and applications can programmatically take advantage of those features.According to Microsoft, WIA drivers are made up of a user interface (UI) component and a driver core component, loaded into two different process spaces: UI in the application space and the driver core in the WIA service space.

In comparison to TWAIN, WIA is said to be more flexible, because it is a standardized interface that doesn't require a tight bundling of scanner software and driver (TWAIN-only scanners are often limited to functions that are enabled in its driver-software-bundle). Most recent scanners support WIA.

Additional information

In 2002, Microsoft released the [http://www.microsoft.com/downloads/details.aspx?familyid=a332a77a-01b8-4de6-91c2-b7ea32537e29&displaylang=en Windows Image Acquisition Automation Library Tool] , which provides access to WIA functionality through programming languages and scripting environments that support OLE Automation.

In Windows XP, WIA runs in the LocalSystem context. Because of the security ramifications of running a service as LocalSystem whereby a buggy driver or malicious person would have unrestricted access to the system, the WIA service in Windows Server 2003 and Windows Vista operates in the LocalService context. This can result in compatibility issues when using a driver designed for Windows XP.Microsoft published a paper in 2003 titled [http://www.microsoft.com/whdc/device/stillimage/secure-drv.mspx Security-related Best Practices for WIA Driver Development] to assist WIA driver developers in writing drivers that will work in the lower-security context that the WIA service operates in.]

Windows Vista has the WIA Automation library built-in. Also, WIA supports "push scanning" and "multi-image scanning". "Push scanning" allows initiating scans and adjusting scanning parameters directly from the scanner control panel. "Multi-image scanning" allows you to scan several images at once and save them directly as separate files. However, video content support is removed from WIA for Windows Vista. [ [http://blogs.msdn.com/wpdblog/archive/2007/02/13/migrating-from-wia-to-wpd.aspx Migrating from WIA to WPD] ] Microsoft recommends using the newer "Windows Portable Devices" API.

ee also

* Image and Scanner Interface Specification (ISIS)
* Standard for image acquisition devices (TWAIN)
* Scanner Access Now Easy (SANE)

References

External links

* [http://support.microsoft.com/default.aspx?scid=kb;en-us;Q293356 List of Scanners That Are Supported by Windows Image Acquisition]
* [http://support.microsoft.com/kb/264598 List of Digital Cameras That Are Supported by Windows Image Acquisition]
* [http://msdn.microsoft.com/en-us/library/ms630368(VS.85).aspx Windows Image Acquisition (WIA): MSDN]
* [http://www.microsoft.com/whdc/device/stillimage/stillimg-connect.mspx Still Image Connectivity for Windows] — describes WIA and compares it to Picture Transfer Protocol and USB Mass Storage methods for transferring images between a digital imaging devices and the computer.
* [http://support.microsoft.com/?kbid=819017] - Windows Explorer Hangs when service is running.