Brother MFC-3240C - Manual (Page 140)

8 - 18 USING YOUR MACHINE WITH A MACINTOSH ®
Color Type
Black & White—Set the image Type to Black and White for text or
line art. For photographic images, set the image type to Gray (Error
diffusion) or True Gray.
Gray (Error Diffusion)—is used for documents that have
photographic images or graphics. (Error Diffusion is a method for
creating simulated gray images without using true gray dots. Black
dots are placed in a specific pattern to give the appearence of gray.)
True Gray—is used for documents with photographic images or
graphics. This mode is more exact because it uses up to 256 shades
of gray. It requires the most memory and takes the longest transfer
time.
Colors—Choose either 8-bit Color, which scans up to 8-bit Color or
24-bit color which scans up to 16.8 million colors. Although using
24-bit color creates an image with the most accurate colors, the
image file will be about three times larger than a file created with 8-bit
Color.