ADF scanners are digital scanners equipped with Automated/Automatic Document Feeders (ADFS). ADF scanners can accept a stack of documents in a tray and process them one at a time automatically, without human attendance or assistance.
ADF scanners are very convenient, especially when scanning high-resolution digital images from color documents which can take a minute or more apiece. You can just plop a batch of photos into a scanner's tray, press a button, and go do something else for an hour or so. When you return you will have a sequentially number set of digital images saved to your hard drive.
ADF scanners are built into office machines other than dedicated scanners. Photocopiers contain ADF scanners. So do fax machines. The very popular space-saving multi-function devices incorporate ADF scanners, photocopier, fax, and printing functions in one small box. Of course, the more functionality one crams into a device, the more things there are to go wrong.
However, there are often points of failure in multi-function devices and other things that include ADF scanners. ADF scanners are complex electromechanical devices with many moving parts: pulleys, gears, drive trains, scanner head, etc. When ADF scanners stop working, productivity plummets. Fortunately most ADF scanners also include a flatbed scanner so you feed documents one at a time, however tedious that may be.
Depending on the model, ADF scanners may produce only black-and-white images or full-color images. Both have their advantages and disadvantages.
Black-and-white ADF scanners are less expensive than color ADF scanners and process documents faster. Single-purpose fax machines include low-resolution black-and-white ADF scanners because that's all fax machines can transmit anyhow. Black-and-white ADF scanners are satisfactory in law offices and other environments where the text of a document is all that matters. Black-and-white ADF scanners are also used in Optical Character Recognition (OCR) applications where only the shape of letters matters, not their color or any images included with the text.
Color ADF scanners are much more versatile than black-and-white ADF scanners. They can produce black-and-white low-resolution scans for faster processing, but their forte' is high-resolution full-color scanning. Once you have a high-resolution color scan you make different versions of it for different purposes. You can shrink the image file's size by reducing its resolution, making transmission over the Internet faster. You can edit a high-resolution color image just about any way you want.
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