Scanner

High quality and very expensive scanner used by repro houses to scan transparencies, negatives and prints. Originals are mounted on the curved surface of a transparent drum. As the drum rotates, a fine beam of transmitted or reflected light scans the original.

Often quoted on scanner specifications to indicate the maximum tone range that the scanner can capture. A higher figure indicates that the scanner will capture more detail from the highlights to shadows. With flatbed scanners that are being used to scan prints this isn't too important because the tonal range has already been reduced in the printing process. A higher dynamic range is essential on film scanners when scanning transparencies that have a wide tonal range. Specialist films, such as Fuji Velvia, are said to have a range of around 3.7D, so the scanner needs to have at least the same dynamic range to ensure every bit of highlight and shadow detail is captured in one scan. Also see "High Dynamic Range"

The resolution of a computer monitor, scanner or printer. The more dots per inch, the higher the image quality - provided, of course, that the image is sharp in the first place.

A file that controls a printer, scanner, disk drive or other device which is part of, or connected to, a computer.

A peripheral that scans slides or negatives and converts them into high resolution digital images.

Computer peripheral with a glass plate that you lay photos prints, artwork or transparencies on to scan and convert into digital images. Most models have an a4 scanning area and cover A3.

Name given to things such as a computer, film scanner, digital back or camera.

A digital picture can be enlarged in size by adding new pixels to the existing grid. Some camera and scanner software do this as the picture is processed to give higher resolution results. The fact is, interpolation increases the picture by guessing what pixels are required and uses information from the surrounding pixels to achieve this. Although the overall picture count will rise image quality can actually suffer and definition is often reduced.

The name used to describe any accessories that connect to a computer such as card reader, printer or scanner.

Software that either allows users to access peripherals, such as a scanner, through their image manipulation software or adds features to an existing application, such as filters or third-party add ons.

A small file thats dropped into the acquire folder of programs such as Photoshop. Then you would go to Twain>Acquire and the computer would connect to the scanner or frame grabber and operate it from within the program.

A device independent colour space used to create consistent color whatever the device used to create or output an image, such as a monitor, printer, computer, or scanner. It consists of a luminance value (L) and two chromatic values A from green to red and B from blue to yellow.

Random coloured pixels that appear in dark or shadow areas when the light levels are below the camera's CCD sensitivity range. Noise is also often seen from scans made using a scanner that doesn't have a wide enough dynamic range to cope with the shadow and highlight areas in one scan. Some image editing programs have a Noise filter that adds a grain pattern to the image to make it look more like a natural photograph taken using film.

Indicates which method the product uses to connect to the computer. SCSI methods are generally the fastest, but also potentially the most difficult to set up, especially when you have several other items connected or installed. SCSI needs a special card installed to support the product. Most PC and new Macs don't have one so you may need to add this. Parallel is the slowest method of data transfer that's normally used to connect a printer to the computer If you also have a scanner or older card reader there's usually an adaptor to run it from the same connection point as the printer. This can protrude further out of the back of the computer so make sure you have the space to allow this.USB and Firewire are the new, easier methods of connection. Firewire is more popular on MAC platforms and is the fastest system, but also currently the least popular. Both recognize that an item has been attached and install necessary software from the supplied CD, using simple help menus. Both can be connected and disconnected with the computer and peripheral turned on. Unlike SCSI or Parallel, where both have to be switched off.

The amount of colours that can be captured by the scanner : 24-bit is 8-bit red, 8-bit green and 8-bit blue, giving a total of over 16 million colours. Most of the latest scanners have 30-bit or 36-bit, to capture billions of colours. In practice it's very difficult to see any difference once you go beyond 24-bit.