Brother DCP-4020C - Manual (Page 104)

HOW TO SCAN USING WINDOWS
®
9 - 5
PreScanning to crop a portion you want to scan
The Pre-Scan button is used to preview an image for cropping any
unwanted areas from the image. When you are satisfied with the
preview, click the Start button in the scanner window to scan the
image.
1
Place the original face down on the scanner glass.
2
Select the settings for Scan (Image Type), Resolution, Scan
Type, Brightness, Contrast and Document Size, as needed.
3
In the TWAIN_32 Brother MFL Pro Scanner Setup dialog box,
click the PreScan button.
The entire original will be scanned into the PC and will appear in
the Scanning Area.
Scanning area