quality:corruption
Contact image sensor (CIS)

Scanners equiped with contact image sensor (CIS) scanning elements are designed to be in near-direct contact with the document to be scanned and thus do not require the complex optics of CCDs scanners. However, their depth of field is much worse, resulting in blurry scans if the scanned document is not perfectly flush against the platten. Because the sensors require far less power than CCD scanners, CIS scanners are able to be manufactured down to a low cost and are typically much lighter in weight and depth than CCD scanners.