Brother MFC-8640D - Manual (Page 156)

USING YOUR MACHINE WITH A MACINTOSH ® 7 - 41
Scan to OCR:
In the General tab
You can enter up to 30 characters 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, OCR Software,
Resolution, Scan Type, Document Size, Brightness and
Contrast settings.