While still having disadvantages compared to traditional scanners (such as distortion, reflections, shadows, low contrast), digital cameras offer advantages such as speed, portability and gentle digitizing of thick documents without damaging the book spine. Due to increasing resolution and new features such as anti-shake, digital cameras have become an attractive alternative to regular scanners. Other types of scanners are planetary scanners, which take photographs of books and documents, and 3D scanners, for producing three-dimensional models of objects.Īnother category of scanner is digital camera scanners, which are based on the concept of reprographic cameras.
A rotary scanner, used for high-speed document scanning, is another type of drum scanner, using a CCD array instead of a photomultiplier. Modern scanners typically use a charge-coupled device (CCD) or a Contact Image Sensor (CIS) as the image sensor, whereas older drum scanners use a photomultiplier tube as the image sensor. Mechanically driven scanners that move the document are typically used for large-format documents, where a flatbed design would be impractical. 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. Common examples found in offices are variations of the desktop (or flatbed) scanner where the document is placed on a glass window for scanning.
In computing, an image scanner-often abbreviated to just scanner- is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image.