Xerox xerox documate manual Contrast, Color image brightness examples, Black background scanners

Scanning from TWAIN and WIA

Brightness works in conjunction with Contrast for image enhancement. When you are adjusting the brightness level to improve the scanned image quality, try adjusting the contrast level as well. The contrast level is the range between the lightest and darkest parts of the image. For example, if you scanned a document with notes written in pencil, you may have to decrease the brightness level to get the handwritten notes to appear in the scanned image. However, when decreasing the brightness, white starts to appear gray in the image. In that case, raise the contrast level to make the differences between the lightest and darkest part of the image more defined.

Color image brightness examples

The examples below show the original image at the default setting of 50% brightness level, 25% brightness and 75% brightness. Adjusting the brightness level does not make the image completely black nor completely white.

Brightness: 25% Brightness: 50% Brightness: 75%

Technical note:

Most monitors have a brightness setting that is user adjustable. When viewing scanned images on-screen, versus printing the image, the brightness setting of the monitor may affect how light or dark the scanned image looks when compared to the original. If the scanned image is too different from the original image, or if adjusting the scanned brightness level does not modify the image how you want, try adjusting the monitor's brightness level. Refer to the monitor's user guide for adjusting the brightness 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 multipart color forms 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 60% and 80%.

Contrast

Contrast refers to the differences between the light and dark portions in the image. Move the slider left or right to decrease or increase the contrast levels. Increasing the contrast level emphasizes the difference between the lighter and darker portions of the image, decreasing the contrast de-emphasizes that difference.

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.

Xerox® DocuMate® 4790	7-141
User’s Guide