Samples per inch

Samples per inch (SPI) is a measurement used in digital imaging and scanning that refers to the number of individual samples or data points taken per linear inch of an image or scanned material. It is primarily used when discussing the resolution of scanned images or the quality of digitized photographic materials. In the context of scanning, a higher SPI often indicates a greater level of detail captured, which can be particularly important for tasks that require high-quality reproductions, such as archival scanning or printing.