What is a scanner?
A scanner is a device that captures images from photographic prints, posters, magazine pages and similar sources for computer editing and display.
Scanners work by converting the image on the document into digital information that can be stored on a computer through optical character recognition (OCR).
This process is done by a scanning head, which uses one or more sensors to capture the image as light or electrical charges.
The document scanner moves either the physical document or the scanning head, depending on the type of scanner. Then, the scanner processes the scanned image and produces a digital image that can be stored on a computer.
Scanners usually attach to a computer system and come with scanning software applications that let you resize and otherwise modify a captured image.
If a printer is hooked up to the computer, you could print a second hard copy of the scanned image and store it in digital format.
What types of scanners are available?
Modern scanners come in handheld, feed-in and flatbed types and are for scanning black-and-white only or color.
- Flatbed scanners are the most common type of scanner. They are called "flatbed" because the document is placed on a flat surface for scanning. Flatbed scanners can scan documents of various sizes and are generally more versatile than sheetfed scanners.
- Sheetfed scanners are designed to scan documents fed into the scanner one at a time. Scanners with automatic document feeders are smaller and more portable than flatbed scanners and are often used in home offices or small businesses.
- Handheld scanners are portable scanners that are smaller than flatbed scanners. They are designed for scanning documents on the go, such as newspaper articles or printed photos.
- 3D scanners are a bit different than traditional scanners in that they collect distance point measurements from a real-world object and translate them into a virtual 3D object.
However, it's also worth noting that scanners are embedded in other devices such as photocopiers, barcode scanners and fax machines used to make copies of documents and images.
In addition to the intended purpose of a scanner, a buyer will also need to know the type of image resolution they need from the scanner.
What is scanner resolution?
Image resolution refers to the number of pixels captured by the scanner sensor and is measured in dots per inch (dpi). The higher the dpi, the greater the scanner's ability to capture detail.
For example, a scanner with a resolution of 1200 dpi can capture 1200 pixels per inch of an image.
Very high-resolution image scanners are used for scanning for high-resolution printing, but lower-resolution scanners are adequate for capturing high-quality images for computer display.
The scanner's resolution is determined by the number of sensors in the scanning head.
Manufacturers of scanners
Some major manufacturers of scanners include Epson, Hewlett Packard, Microtek and Relisys. These companies offer a variety of scanner types and resolutions from which to choose.
For example, Epson offers flatbed and handheld scanners, with resolutions ranging from 300 dpi to 12800 dpi.
Hewlett Packard offers sheetfed and flatbed scanners, with resolutions ranging from 1200 dpi to 4800 dpi.
Microtek manufactures only flatbed scanners, with resolutions ranging from 1200 dpi to 3200 dpi.
Relisys manufactures both sheetfed and flatbed scanners, with resolutions up to 2400 dpi.
When choosing a scanner, consider the type of scanner you need as well as the image resolution you require. Pricing varies depending on the brand, type, resolution and whether it is intended for personal or business use.
Decide on a budget first, then compare the features offered by different manufacturers to find the scanner that best meets your needs.
See also: 2D barcode, document reader, document capture, enterprise document management, TWAIN