Brendan MacRae wrote: >Whether or not people are wrong in equating dots and >pixels the terms are often used interchangeably since >monitor resolution is measured (or used to be anyway) >in "dot pitch." Hence part of the confusion between >dpi and ppi. > >My scanner also measures pixels per inch but even the >side of the box reads "4000 DPI." So, perhaps some of >criticism for the confusing nomenclature should be >leveled at Nikon (and others). After all, it's a >scanner not a printer, right?
In the case of a scanner you're pretty safe using either term, DPI or PPI: A scanner looks at one tiny area (a dot) on the physical medium and generates one digital picture element (pixel) from it. So at this particular boundary between the digital and analog realms, one dot = one pixel, hence PPI and DPI are equivalent. But once you have a digital file, DPI makes no sense because there are no "inches" to a digital file. And at the final digital/analog boundary, the printer, DPI and PPI are still not equivalent because inkjet printers make "dots" in separate, individual colors and at DPI resolutions (1440 DPI - 2880 DPI) far beyond what's sensible for PPI output res of a digital file. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
