what exactly is 3200 CPI in DPI ? (check the GIF in yamaha200's post)
3200 CPI = 3200 DPI.
CPI=counts per inch=number of changes in detected signal state per inch of movement.
DPI=dots per inch=number of dots that can be discretely sensed per inch.
Guess what? They are the same thing. No need to get worked up over which is the right terminology, they are both accurate and meaningful.
LPI=lines per inch=number of individual lines that can be sensed per inch=
half the number of DPI since you are counting black lines on white background (or vice versa.) Photography term.
PPI=[strike]points[/strike] pixels* per inch=number of image pixels that a printer can print per inch. Much lower than the printer's DPI because you need many ink dots in a dithering pattern to create desired image colours from the limited number of ink colours.
Edit> (*) Better not confuse it with points used in font design (point=1/72"), so I'll stick with pixels.