User's Manual

Scanning from TWAIN and WIA
Xerox
®
DocuMate
®
4799
User’s Guide
7-142
Adjusting the contrast level is based on how you want the image to appear and there is no standard to adhere to.
Contrast works in conjunction with brightness for image enhancement, when decreasing the brightness level, the
overall image becomes darker, in which case you may want to increase the contrast level so that the differences
between the lighter and darker portions of the image are clearer.
Below are some recommended options for contrast image correction based on the original document quality.
• Original documents of good quality - 50%
• Pencil written letters, forms, or drawings - 55% to 65%
• Faded pictures or old documents with faded text - 60% to 70%
• Light colored carbon copy paper, such as yellow or pale pink or pale green, with light text - 45% to 55%
• Newspaper or magazine pages - 55% to 70%
• Book pages - 60% to 75%
• Pictures taken inside or in the shade - 40% to 60%
Color image contrast examples
The examples below show the original image at the default setting of 50% contrast level, 25% contrast and
75% contrast.
Technical note:
Most monitors have a contrast setting that is user adjustable. When viewing scanned images on-screen, versus
printing the image, the contrast setting of the monitor may affect how clear a scanned image looks when
compared to the original. If the scanned image is too different from the original image, or if adjusting the
scanned contrast level does not modify the image how you want, try adjusting the monitor's contrast level. Refer
to the monitor's user guide for adjusting the contrast level and see if the manufacturer has any recommended
settings.
Black background scanners:
Some scanners have a black background plate. A black background results in more precise cropping results and
skew detection. However, when scanning thin paper, such as carbon copy paper or ruled writing paper, which are
less than 18lb paper weight, the background may “bleed” through into the final image and make the image
darker than it should be. In that case, try adjusting the brightness level between 40% and 60%, then adjust the
contrast level between 60% and 80%.
Contrast: 25% Contrast: 50% Contrast: 75%