Dots Per Inch (DPI) refers to the number of dots of ink used to create an image on a physical page. DPI differs from PPI (Pixels Per Inch), which refers to the number of pixels needed to create a digital image.
The more dots per inch, the higher the quality of the picture. This means more resolution, more sharpness and more details. Digital images with higher resolution settings can produce more detailed photographic prints. To get more options for reprints and copies, scan at a higher DPI or PPI. If you would like to make enlargement reprints from the digital files, scan at 600 dpi.