ppi is Pixels-per-Inch and is the more precise term. dpi or "dots-per-inch" is a less precise term, depending on whether you are talking about a file, a printer, or a piece of film output.
For the purposes of photography, the terms are pretty much interchangable.
Remember that its "per-inch" -- if the total number of pixels is the same, it matters not what resolution the file is set to, until you go to print it. A file 100x200 pixels will print 1x2 inches at 100ppi, but 10x20 inches at 10ppi -- the same data, spread over a larger or smaller area.
If you think of a pixel as a little mosaic tile, it may help you visualize ... you have a fixed number of tiles, but each one can be smaller or larger depending on how big an area you want to cover.
For printing, you want to have at least 150ppi at the final output size; 300ppi is great.
Message edited by author 2005-10-26 13:50:44. |
