(dots per inch) a way of measuring how much ink is put on the page by a printer 〔计算打印机在页面上用墨量的〕每英寸点数
From Longman Business Dictionary
dpidpi, DPI
COMPUTING (dots per inch) a measure of how clear the details of an image produced by a printer, scanner etc are. The more dots there are per inch, the clearer the image
Laser printers are typically 300 to 600 DPI and commercial typesetters are usually around 1200 DPI.