Visual content	Issues for visual content	Image production	Image acquisition	Image manipulation	Image creation

A flatbed scanner operates similarly to a photocopier, but saves the image to computer instead of printing on paper. It has a computer interface that is usually accessed from an image editing program, but may operate as stand-alone software. This allows you to set specifications for your scan, and to save it to disk.

The flatbed scanner has a glass plate under a lid, and a moving light that scans across under it. It allows you to scan photos, paper documents, books, magazines, etc and create a digital image, which we can see on the screen, save as a file, print or use in a website.

A flatbed scanner with a transparent media adapter (TMA) will also allow you to scan images from film. It is not the best method of scanning 35mm transparencies, as they require substantial enlargement, but is useful for larger format transparencies that a dedicated film scanner may not be able to accommodate.

Software is used to operate the scanner ­ all scanners come with basic scanning and image editing software bundled, or a plug-in is provided to enable the scanner to be used with your preferred software (eg Photoshop). The image editor program will usually have a menu at 'File - Acquire' or 'File - Import' or 'File - Scanner' that you use to scan an image. This menu starts the scanner's software, called a TWAIN driver, which is a software standard for image acquisition devices.

The TWAIN driver is the software provided by the scanner manufacturer to operate the scanner and will always have a proprietary name (eg ScanWizard, VistaScan, FotoLook or PrecisionScan). You can use any image editing program, but you must use the provided TWAIN driver for your scanner.

This software provides the interface that has the scan settings:

• set the mode (colour or B/W or line art),
• set resolution and scale
• set the area for scanning, and use controls to help correct the tonal quality and colour balance of the scanned image.

It is recommended that images be scanned larger and at a better colour depth than you intend to use them. This allows flexibility in editing and re-using the image, and ensures minimum degradation of the image. Beware of high-resolution scans (over 600dpi) - these are often not true optical resolution but are created by 'interpolation' (software creation of 'fake' pixels). Resolution over 300dpi will not usually be required for web or desktop print images.

After the scan completes, the image is transferred into the image program memory. The image can then be further adjusted, then saved to disk.

Summary:

• A flatbed scanner copies images to your computer.
• It can also copy documents and large format transparencies (with an adapter).
• Software is required to provide an interface with the scanner (TWAIN driver), to manipulate scanned images (image editing software) and to convert scanned documents to text (OCR software).
• Scanner settings allow you to set image mode and image size, and to crop and make tonal adjustments. Scan images larger and higher quality than you need.