IBM Ricoh ImageReader FB735 - Manual (Page 27)

4.-5
Gray (256 levels gray scale)
Gray presents a 256 shades of gray in an image.
256 Color
The 10 bits color information presents 256 colors
and gives more tonal range and subtlety in an image.
True Color (16.7 million colors)
The 30 bits True Color presents 16.7 million color
and give much more tonal range and details in a
color image.