Desktop scanner with the lid raised. An object has been laid on the glass ready for scanning.

Scan of the jade rhinoceros seen in the photograph above.

Image scanner.

In computing a scanner is a device that optically scans images printed text handwriting or an object and converts it to a digital image. Common examples found in offices are variations of the desktop scanner where the document is placed on a glass window for scanning. Hand-held scanners where the device is moved by hand have evolved from text scanning "wands" to 3D scanners used for industrial design reverse engineering test and measurement orthotics gaming and other applications. Mechanically driven scanners that move the document are typically used for large-format documents where a flatbed design would be impractical.

Modern scanners typically use a charge-coupled device or a Contact Image Sensor as the image sensor whereas older drum scanners use a photomultiplier tube as the image sensor. A rotary scanner used for high-speed document scanning is another type of drum scanner using a CCD array instead of a photomultiplier. Other types of scanners are planetary scanners which take photographs of books and documents and 3D scanners for producing three-dimensional models of objects.

Another category of scanner is digital camera scanners which are based on the concept of reprographic cameras. Due to increasing resolution and new features such as anti-shake digital cameras have become an attractive alternative to regular scanners. While still having disadvantages compared to traditional scanners digital cameras offer advantages such as speed portability gentle digitizing of thick documents without damaging the book spine. New scanning technologies are combining 3D scanners with digital cameras to create full-color photo-realistic 3D models of objects.