Microsoft Office XP Document Imaging: Using Scanners

Twain drivers and WIA drivers

Most scanners use TWAIN drivers to communicate status and settings between the scanner and the computer. In Microsoft Windows® Millennium Edition and later, scanners may also include Windows Image Acquisition (WIA) drivers. Microsoft Office Document Imaging attempts to communicate with your scanner using these drivers to determine your scanner's capabilities and to obtain the image from the scanner.

Office Document Imaging includes a database of recognized scanners and drivers. If your scanner is included in the database, you do not need to complete the scanner test. Also, if Office Document Imaging recognizes your scanner, you will be able to scan images without using the custom scanning user interface provided by the scanner manufacturer. Of course you can select to use either program to scan images into Office Document Imaging.

WIA drivers may not work for scanners with automatic document feeders. If you have a scanner with an automatic document feeder, you should install and use the TWAIN driver for best results.

Occasionally scanners will be operating using a TWAIN emulation driver. Office Document Imaging does not work with emulation drivers. Contact your scanner manufacturer for the most recent version of TWAIN or WIA driver for your scanner.

File formats and compression

Microsoft Office Document Imaging stores scanned images in Tagged Image File Format (TIFF). The resulting file is larger than the same image stored in Joint Photographic Experts Group (JPEG) format.

Tagged Image File Format (TIFF)

TIFF is a commonly used format for various imaging programs, including those that scan and fax. Office Document Imaging uses the TIFF format exclusively, utilizing the format's capability to contain text recognized by optical character recognition (OCR). When you scan new documents, they are saved in TIFF format (with a .tif extension), and any OCR text is stored in the TIFF file along with the image.

You can open and edit TIFF files created with Office Document Imaging by using many other graphics programs. When you do so, any OCR text that the file contains is lost. You will have to rerun OCR if you want to access the text in the TIFF file again in Office Document Imaging.

Joint Photographics Expert Group (JPEG)

JPEG is the most common file format for Web graphics. JPEG files are compressed to a fraction of the original file size, which allows for faster downloading of images. Because of the way JPEG files are compressed, there is a loss of detail and clarity when compared to the original image. The loss of detail affects OCR quality. When the image is in JPEG format it is much more difficult to get good OCR results. This is why Microsoft Office Document Imaging files are stored in TIFF and not JPEG format.

Tips about compression and file/OCR quality

Office Document Imaging can be used to view standard TIFF files from other programs. Faxes received in e-mail or through a fax program on your computer are often stored as TIFF files. You can open these files in Office Document Imaging and then run OCR to extract the text from the fax. Running OCR and saving the file will also let you find text within the fax from search dialogs. When you save a TIFF file in Office Document Imaging it will add the OCR information to the file and then compress the original image.

Scanned images are most often 300 dpi. Images with less than 300 dpi will not OCR as well as images scanned at a higher resolution (300 or 400 dpi). However, OCR does not significantly improve for resolutions greater than 900 dpi. Office Document Imaging limits files to a maximum of 900 dpi when compressing and saving files.

Adding pages to multi-page scanned files

In Microsoft Office Document Imaging you can drag several files and drop them into one individual file to create one larger file. For example, you can scan all the receipts from your last business trip or a home building project and keep them in one file for easy reference. If you forget a receipt, you can easily add it to the rest:

Open the file with all the previously scanned receipts.
Open a second instance of Office Document Imaging and scan in the forgotten receipt.
Click the thumbnail of the newly-scanned receipt, drag the thumbnail and drop it into the other document containing all the receipts. This automatically inserts the new receipt into the older file.
Be sure to save the file that contains the newly-added thumbnail.

You can also use the thumbnail view to re-arrange the pages within a multi-page file.

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