Xerox
®
DocuMate
®
3640
User’s Guide
175
Choosing contrast values
While Brightness adds the same amount of gray or white to all pixels in the image, Contrast adjusts
the pixels based on the pixel color level. For instance, increasing the contrast level will add white to light
colored pixels and gray to dark pixels to make the difference between color levels in the image crisper.
Decreasing the contrast level will have the opposite affect, where light colored pixels are modified with
gray and dark pixels are modified with white to make the transition of colors in the image appear
smoother.
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.
Contrast: 25% Contrast: 50% Contrast: 75%
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