Xerox Documate 4790 User Guide

Scanning from TWAIN and WIA
Xerox
® DocuMate® 4790
User’s Guide7-143
Gamma
Gamma is the tone curve and starting point for image enhancement. Move the slider left or right to darken or 
lighten the image. As you raise or lower the Gamma value, the values at which Brightness and Contrast affect 
the image are changed. It is recommended that you keep the default gamma value, or adjust this setting before 
adjusting the other options. 
Choosing gamma values
As the gamma value is adjusted lower, the tone...

Scanning from TWAIN and WIA
Xerox
® DocuMate® 4790
User’s Guide 7-144 When scanning in black and white, each pixel is reversed from black to white and white to black. When scanning 
in grayscale each pixel is reversed to the opposite level of gray. When scanning in color each pixel is reversed to 
the opposite color in the color wheel.
For example, you might choose this option if you are scanning pages that have been printed from newspaper 
microfilm. Newspaper microfilm reverses black and white so that...

Scanning from TWAIN and WIA
Xerox
® DocuMate® 4790
User’s Guide7-145
Bit Depth Reduction
The Bit depth reduction options are only available when scanning in black and white. Click the drop down menu 
and select an option from the list.
Threshold and Dynamic threshold
Threshold enables you to set what level of light or dark to look for on a page. When scanning in black and white, 
everything on the page is set to either white pixels or black pixels in the final image. If the text on the page is a 
light...

Scanning from TWAIN and WIA
Xerox
® DocuMate® 4790
User’s Guide 7-146 Bayer dither scan - Close up
Mixed Content Options (Text and Graphics)
The Bit depth reduction list includes automatic separation options for mixed content documents containing both 
text and graphics.  These options enable the scanner to evaluate the image for text and graphics, and then apply 
threshold to the text regions and a dither pattern to the graphics regions. This retains text clarity while providing 
graphic legibility....

Scanning from TWAIN and WIA
Xerox
® DocuMate® 4790
User’s Guide7-147 • The position of the hole cannot be flush to the edge of the margin area and it cannot overlap the edge of 
the margin area
Color Processing Panel Options
The options in this panel are for setting how the scanner should process colors in specific color modes.
Color Dropout
Color dropout tells the scanner and software to remove a specific color from the image. You can choose either 
Red, Green, or Blue, or define a custom color, to be...

Scanning from TWAIN and WIA
Xerox
® DocuMate® 4790
User’s Guide 7-148 This option is only available when scanning in grayscale or black and white. The example below shows the 
original text with a red watermark and the resulting image with the color removed.
Perform Color Correction
Apply color correction to the image so the displayed colors approximate the original item colors. Select this 
option to use the scanner’s default Gamma table which has been calibrated to produce the best quality color...

Scanning from TWAIN and WIA
Xerox
® DocuMate® 4790
User’s Guide7-149
Despeckle
This option removes speckles from the background. Speckles are small spots on an image that the scanner 
interpreted as a valid part of the document. For example, an irregularity in the paper, a small wrinkle, or holes 
where a staple was removed may show up as speckles in the scanned image. The Despeckle option identifies 
these spots and removes them. This option is only available when scanning in black and white....

Scanning from TWAIN and WIA
Xerox
® DocuMate® 4790
User’s Guide 7-150 Moiré radius—you can set the size of the area to be evaluated in the Moiré radius field. Adjusting the radius will 
produce different results for the various types of items that can be scanned. With this feature, you may have to 
test scan a few times, adjusting the Moiré radius as needed, until you obtain the best results for the type of paper 
in your scan job. Note that the higher the number is in the Moiré radius field, the longer...

Scanning from TWAIN and WIA
Xerox
® DocuMate® 4790
User’s Guide7-151
Initialize White Level From Document
Automatically detect and adjust the white level using the leading edge of the scanned item. This is a feature that 
uses the scanner for processing and it is available whether or not Visioneer Acuity is installed.  However, please 
note that there will be a black line at the top of each image.  This is where the scanner starts the image capture 
as the reference point for it to detect and set the...

Scanning from TWAIN and WIA
Xerox
® DocuMate® 4790
User’s Guide 7-152
Driver Configuration
Use the Driver configuration section to configure the add-on modules, select interface options, and view the 
scanner hardware properties. When the Advanced configuration mode is selected, a scanner panel option will be 
available for you to change any hardware settings that may be available for your scanner.
Disabled Options in this Section
Some options in the interface may be grayed out and cannot be selected....