About scanning, screen, and print resolution
Resolution is the sharpness of an image, usually measured in pixels per inch (ppi) or dots per inch ( dpi). While you work with scanners, digital cameras, and electronic images, it is good to understand the different types of resolution:
Scanning resolution — The optical resolution at which an item is scanned.
Screen resolution — The resolution of a computer monitor. Most PC monitors have a screen resolution of 96 dots per inch (dpi).
Print resolution — The resolution of an inkjet, laser, or image setter printer. The resolution for a printer refers to the dpi on a printed image.
The higher the dpi of an image, the greater the resolution. High resolution settings create larger files that occupy more disk space on your computer.
The image file format and quality setting also affect file size. Some formats store the image as uncompressed data. Other formats use various compression techniques to reduce file size.
File size is important if you plan to post the image to a web site or e-mail the image over the Internet. Image files for web sites should be less than 200 KB in size, and for e-mail should be as small as possible.
Generally, when you scan an item for printing or DTP work, the scanning resolution should be high, whereas when you scan an item for web viewing, the scanning resolution can be lower. MRC-compression optimizes quality and file size.