You will need higher pixel resolution digital files for printing than you will for web placement or email attachments. This is because most photo printing is done between 240 and 360 dpi. The human eye sees photo prints with printer output resolutions equivalent to 240 ppi and above as continuous tone image even though the image is actually made up of slightly overlapping DOTS. At output resolutions of 240 ppi and above the dots are very small and since they overlap each other they are hard to see without some sort of magnification aid. High output resolution (more dots per inch) allows for more subtle color shade gradations in the different graphical components of a photograph. Higher output resolutions also produce sharper details in the image. It follows that prints made with output resolutions between 300 and 360 ppi will look better than prints made with output resolutions between 150 to 240 ppi.

Computer monitor displays are between 72-90 dpi depending on the monitor's size and currently set resolution. As an example a 17 inch monitor is actually about 13 inches side to side. That "13" inch monitor when running 1024X768 pixel screen resolution would be displaying at about 78 ppi. Math as follows: 1024 divided by 13 = 78 ppi.

Digital images that are intended for web use or email attachments usually run between 150X250 pixels for small "thumbnail" images to 600X800 pixels for full or nearly full page images. Digital images of 600X800 pixels and smaller will fit without scrolling on almost all recently manufactured computer set ups.

Digital images that you will want to print as photographs will require quite a bit more image resolution (more pixels, width and height). We'll discus how to determine the image resolution (pixel dimensions) necessary for any given print size a little later in this tutorial.

You can resize a digital image to smaller resolution without any noticeable quality loss. Resizing an existing digital image to higher resolutions always incurs some image quality loss since the program doing the resizing has to make educated guesses (interpolation) when assigning the colors of the pixels it is adding to build up the resolution of the image. So, If you have a lot of hard drive space or camera memory card space, always scan or take your digital camera pictures at the highest possible resolution. Saving hi resolution files gives you the most flexibility for later uses of your digital image.