Brother MFC-J425W Software User's Manual page 160

Scanning
c
Drag the mouse pointer over the portion you want to scan (1).
d
Load your document again.
Note
Skip this step if you loaded the document on the scanner glass in step a.
e
Adjust the settings for Resolution, Scan Type, Brightness and Contrast in the Scanner Setup dialog
box as needed.
f
Click Start.
This time only the chosen area of the document appears in the application window.
g
You can refine the image in your editing software.
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