The Scanning specification dialog: Image settings for SCSI scanners

Color dropout	Ignores the specified dropout color when you are scanning black and white pages.
Background dropout	Ignores unnecessary background dropout colors altogether while extracting information, in black and other colors, in the foreground of the image. Enabled when Color dropoutis selected.
Threshold dropout	Uses the scanner-specific threshold value for color dropout. Enabled when Color dropoutis selected.
Auto deskew	Straightens skewed images.
Auto crop	Crops the scanned image to the physical dimensions of the actual page that was scanned, if the paper size is smaller than the one selected in the program.
Page length detect	Enables scanning of long pages.
Filter shading	Removes darker areas of the background.
White level follow	The scanner always looks at the first 3 mm of a scanned page to determine what the white level is for the rest of the document. Data that is darker than this level is considered to be image data, and lighter data is considered to be background. When set to Auto, the function is automatically turned on for black and white documents and turned off for halftone or documents.
Overscan	Corrects poor images received from Kodak scanner model 3520DS and Fujitsu scanner model fi-4860C2. It tells the scanner how much of the image area to extract from the top (or leading edge) and bottom of the page. Note: With Kodak scanners, this should not be used together with automatic deskewing.