The physical resolution
at which a device can capture an image. The term is used most frequently in reference to optical scanners
and digital cameras
. In contrast, the interpolated resolution
indicates the resolution that the device can yield through interpolation
— the process of generating intermediate values based on known values. For example, most scanners offer an optical resolution of 300 dpi
, but an interpolated resolution of up to 4,800 dpi. This means that the scanner can actually capture 90,000 pixels per square inch. Then, based on the values of these pixels, it can add 15 additional pixels in-between each pair of known values to yield a higher resolution.