Extra features
OCR: Optical character recognition (OCR) software is sometimes supplied with the machine. This allows you to scan in documents to extract the text for editing. One of the biggest challenges for OCR software is whether it can accurately pick up the characters "r" and "rr" and not confuse them as "t" or "n". A good feature that is sometimes available with OCR software is an interface which allows you to directly compare the scanned text to the original document side-by-side to find any errors.
ADF: An Automatic Document Feeder (ADF) is convenient if you need to frequently fax, copy or scan multi-page documents and don't want to individually feed each sheet. Most ADFs should be able to handle at least 30 pages.
Printing onto CD/DVD surfaces: Some devices on the market will enable this, usually using a special disc-holding tray, which is handy if you want to make CDs and DVDs.
Printing on other surface/media: Other media may include overhead transparencies, labels, stickers, envelopes etc.
Dual paper trays and two paper paths, or an option to add more trays: This feature might be useful for extra capacity in office situations or where large documents need to be printed regularly. Most devices tend to have capacity for 100-150 pieces of paper at any one time in the input tray; with two trays, this capacity is doubled.
Support for different paper sizes and types: 4x6in photo paper, A4, A3 etc and glossy/semi-gloss, matt etc.
Descreening function: This allows you to take out patterns that can be evident when scanning magazine or book images.
Print from an index sheet: If the device has a memory card reader, you may be able to print from an index sheet straight from you memory card. You can then mark the photos that you want to print, scan them back to the device and it will print your selected photographs. This is handy for ease-of-use when printing a number of photos and saves the need to individually select each photo through the PC or control panel.
Scan 3D images (physical objects) with relatively good accuracy.
Scanning directly to a number of different formats eg, PDF/JPEF/TIFF/WORD.
Digitally sending documents or to scan direct to e-mail or particular folders on your PC/network.
Scanning film or slides: This can be handy for photographic enthusiasts though you will invariably lose image quality, and often pick up dust, which will result in a grainy appearance.