The British Library

Glossary

Helpful information about terminology used throughout our website complete with links to further reading for many subjects.

CD-R - CD-Recordable: a CD-R compact disc can only be written to once, and is an ideal storage medium for digital photos.

 

Colour Profile: The colour profile is a calibrated dataset that controls the gamut of colour within an image with the aim of reproducing consistent colour from one device to another.

 

DPI - Dots Per Inch: DPI is used for printer resolution. DPI is not the image resolution although frequently used that way.

 

DVD -R - DVD-Recordable: a DVD-R can only be written to once, and is an ideal storage medium for large numbers of digital photos.

 

FTP - File Transfer Protocol: a standard network protocol used to copy a file from one host to another over a TCP/IP based network, such as the internet (World Wide Web).

 

ICC - International Colour Consortium: Established in 1993 for the purpose of creating, promoting and encouraging the standardization and evolution of an open, cross-platform colour management system. More information about ICC is available from www.color.org
 

Image Resolution - The number of pixels in a digital photo is usually referred to as its image resolution.

 

JGP or JPEG - Joint Photographic Experts Group: standard for compressing image data developed by the , Strictly speaking, JPEG is not a file format, but a compression method. Images Online Jpegs are saved to a Photoshop compression setting of 12 (12 =highest quality, 1= low quality) offering no perceivable loss of image quality from a tif file but much smaller for storage and transmission. More information about JPEG is available from www.jpeg.org
 

MB - Megabyte: a measurement of data storage. 1MB = 1024 kilobytes (KB).

Pixel - Picture Element: digital photographs are comprised of thousands or millions of pixels, the building blocks of a digital photo or image.

Pixel Depth: Sometimes referred to as colour depth or bit depth. Each channel of colour is assigned a value, or bits per channel. For RGB images we have three channels each channel will be in either 8 or 16 bit. 3channels x 8bit = 24bit image. Each pixel has a value between 0 and 255.

 

PPI - Pixels Per Inch: the measure of the number of pixels displayed in an image.

 

RGB - Red, Green, Blue: the three colours to which the human eye, digital cameras and many other devices are sensitive. RGB images refer to the three channels of colour used to build colour fidelity. By combining these three colours any other colour can be produced.

 

Thumbnail - A small version of a photo / image.

 

Tif or TIFF - Tagged Image File Format: Uncompressed image file available offline from images online on request. More information about the TIFF file format is available from Adobe Systems Incorporated.

 

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