Brother MFC 8840D A - Manual (Page 157)

USING YOUR MACHINE WITH A MACINTOSH ® 7 - 41
Customizing a user-defined button
To configure a button, click on the button while holding down the Ctrl
key, and the configuration window will appear. Please follow the
following guide lines for the button configuration.
Scan to Image:
In the General tab
You can enter up to a 30 character name in the Name for Custom
field. This name will appear as the button name.
Select the type of scan from the Scan Action field.
In the Settings tab
You can select Target Application, File Type, Resolution, Scan
Type, Document Size, Brightness and Contrast settings.