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Scanning from TWAIN and WIA
Xerox
®
DocuMate
®
4790
User’s Guide
7-131
• Blank threshold—you can use the Threshold slider to fine tune the sensitivity of the blank image detection.
The results will depend on the scan settings and the types of documents being scanned. In general leave the
threshold level at the default setting if you are scanning good-quality documents printed on standard 20lb
printer paper. Try lowering the sensitivity level if your documents contain light colored text or drawings so
those pages are not detected as blank. Raise the sensitivity level if you are scanning double-sided light-
weight paper where images from the opposite side of the page may appear in the image of the blank side.
Clean Up Edges
Select this option to remove any thin lines from around the edges of the final scan. This option will fill the
margins of the image with the detected edge color. When you select this option, the Width input field will
automatically enable for you to input the size of the area you want to have filled with the background color. You
can specify a fill size between approximately 0.04 to 0.39 inches (1 mm to 10 mm).
Automatic Image Cropping
Depending on the scanner model and installed software, there may be more than one auto cropping option in
the interface.
• Crop to original—select this option to let the scanner automatically determine the size of the item being
scanned. This option is only available if the scanner supports this feature. This option may occasionally be
grayed out as not all scanning applications support this feature.
Always properly adjust the paper guides to the width of the paper in the input tray so that the pages feed
into the scanner as straight as possible. Skewed pages may not crop properly.
• Crop to length—this option tells the scanner to crop the final image to the bottom of the page being
scanned. This option is only available if the scanner supports this feature. This option may occasionally be
grayed out as not all scanning applications support this feature.
Compression Options
There are two types of image compression functions used during scanning. The input compression option is
compressing the image when transferring it from the scanner to the TWAIN driver on the computer. The output
compression option is the TWAIN driver compressing the image before it sends the image to the scanning
application. In the scanning interface the input compression option is Compress transfers and the output option
is Compression.
Compress transfers
Select this option to have the scanner compress the image in Gray and Color scans. This reduces the file size and
allows for faster image transfer from the scanner to the computer. Once the compressed image is on the
computer, scanner’s driver will then uncompress the image, and perform any image processing functions that
have been selected in the scanning interface. The uncompressed image is then transferred to the scanning
application. With Compress transfers, a scanning application such as Nuance PDF Converter, will receive the
uncompressed image and save the image in whatever file format it uses. You can use the Quality slider to adjust
the level of compression you want to use.
When the Quality option is set to High quality, there is very little visual difference between a compressed scan
and an uncompressed scan. When the quality option is set to High compression, there may be a greater visual
difference between compressed and uncompressed scans.