Scanner quality is determined in a similar way to that of printers because the criteria used is optical resolution and colour depth. A scanner's resolution will describe the image detail and is measured in pixels per inch (ppi), which is also sometimes referred to as samples per inch (spi). The colour depth is the number of colours the scanner can handle and is measured in bits, e.g. 24 bits.
A typical flatbed scanner will have an optical resolution of between 1600 to 3,200ppi and 24 or 48 bit colour depth and a high quality scanner will scan at least 5,400ppi with a 48 bit colour depth.
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Next: Connecting a Scanner