Scanner Resolution Limits When You Use WIA Drivers

When you use Windows Imaging Acquisition (WIA) drivers, you may be unable to scan at resolutions that are greater than the maximum resolution of your scanner. For example, if your scanner is capable of scanning at a maximum of 1200 Dots Per Inch (DPI) resolution and you are using WIA drivers, you may be unable to scan at a resolution that is greater than 1200 DPI. Note that this may occur even if you were previously able to scan at a higher resolution by using a third-party program.

WIA drivers and the Scanner and Camera Wizard support the actual optical resolution that a scanner is capable of. Optical resolution represents the amount of detail that is visible in an image before any software manipulation occurs. Third-party programs and drivers can support interpolated resolution. Interpolated resolution is software-enhanced resolution, and because of this, interpolated resolution may exceed the actual optical resolution that a scanner is capable of.

To enable your scanner to use the interpolated resolution that is provided by the software that came with the scanner:

1. Click Start, click Control Panel, double-click System, click the Hardware tab, click Device Manager, and then locate your scanner under the Imaging Devices branch.
2. Right-click your scanner, and then click Update Driver to start the Hardware Update Wizard.
3. Click Install from a list or specific location (Advanced).
4. Locate and click the manufacturer-supplied drivers, and then click Finish.

This behavior is by design.

Although interpolated resolution may capture less detail than optical resolution, it may be useful for certain tasks such as scanning line art or enlarging small originals.

The Scanner and Camera Wizard is able to determine the maximum optical resolution of a scanner, and uses this information to set the maximum DPI you can use for a scan job.

For additional information about scanner and camera use with Windows XP, click the article number below to view the article in the Microsoft Knowledge Base: