The scanner is a device that can scan optically text or images, objects etc. then it converts them into digital images. In offices nowadays can be found many flatbed scanners, very easy to use. The documents are placed on the glass and just by pushing a single button, the scan is done. Another type of scanner is the one that can be held in the hand. The hand moves the device over the object. These scanning wands are used for engineering, industrial design, different tests and measurements, gaming and other applications.
Another type of scanner is the mechanically driven one. This scanner can be used for documents in large formats where the flatbed design is highly impractical.
The modern types of scanners use a charge coupled device (CCD) or even a Contact Image Sensor (CIS). These are the modern image sensors. The old ones use the photomultiplier tube. Another type of drum scanner is the rotary scanner. Instead of the photomultiplier, this one uses a CCD array. Other scanner types are: planetary scanners, for books and documents and 3D scanners. The 3d ones produce three-dimensional models of the scanned objects.
The digital camera scanner is another type of scanner. The concept behind this is the use of reprographic cameras. This camera has increased resolution and some new features like the anti-shake option. These digital cameras are a very attractive alternative to the regular scanners. There are some disadvantages also like the: shadows, reflections, distortion, and low contrast). But still, the digital cameras bring advantages like speed, portability, and also a gentle handling of the thick documents, without doing any damage to the book spine. The newest scanning technologies combine the 3D scanners with the digital cameras. In this way, they create photo-realistic 3D models, full-color representations of the scanned objects. Also, in the biomedical area, the DNA detection devices are also named scanners. These ones have a very high resolution (up to 1 µm/ pixel), just like the microscopes. A photomultiplier tube (PMT) does the detection.
Applications Programming Interface
Applications like Adobe Photoshop are allowed and must communicate with all the scanners. Different scanners use different protocols. The programming had to be simplified to allow a good connection. This is how API (Applications Programming Interfaces) was created. API is a uniform interface that connects the scanner to different programs. This means you don’t need to know a lot about the scanner in order to connect it and get access to it in a direct way. For example, Adobe Photoshop supports TWAIN standard and this means that he can take images from a scanner that uses the same protocol. This is theoretically. In real life, there are communications problems quite often and they appear from the bad API implementation.
The majority of the scanner manufacturers use TWAIN API. Some time ago. This TWAIN API, was used for the low-end or home-uses equipment. Nowadays it has become very popular and used for the scanning of large-volumes.
Other API scanners
The ISIS, is made by Pixel Translations. It uses the SCSI-II for some performance reasons and large machines use it.
The SANE (Scanner Access Now Easy) is open source API program for accessing scanners. It is free and was first developed for the Unix and the Linux operating systems. It has been developed for Microsoft Windows and for OS/2, Mac OS X also. The downfall of this in comparison to the TWAIN, is that it doesn’t handle the user interface.
The Windows Image Acquisition (”WIA”) is a program done by Microsoft.
But the scanners today come with software that recognizes programs like Photoshop.
