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LAN See Local Area Network.

Linear Tape Open (LTO) This is an open tape standard developed by IBM, Hewlett-Packard and Seagate, which has two formats based on the physical size of the storage; 25 GB for the Accelis, 100 GB for the high capacity Ultrium. See Advanced Intelligent Tape (AIT), Digital Linear Tape (DLT), Magneto Optical Disk (MOD), Jukebox, Digital Audio Tape (DAT) and Digital Versatile Disk (DVD).

Little endian Words in computers words are created from 2 or 4 bytes. In little-endian architectures, the rightmost bytes are most significant. In big-endian architectures, the leftmost bytes are most significant. Most PCs use little endian architecture; big endian architecture is mainly used in large computers. See Big endian, Word and byte.

Local Area Network (LAN) A computer network that spans a small area, e.g. an office, with each computer being a node on the network. See Wide Area Network (WAN).

Long Term Archive (LTA) This refers to two types of archives nearline and offline. See Short Term Storage (STS), Nearline archive, Online storage, Offline archive, and Everything Online (EOL).

Look-Up Table (LUT) The purpose of a LUT is to take in one value and to output another using a scale. It is a technique to perform a conversion on pixel data. When the pixel values are decoded they are in a normalised range. To transfer to a grayscale the normalised data is windowed into a series of sub-ranges which contain all the important information and a non-linear conversion is then applied. For each modality the conversion is based on different tables, i.e. the CT pixel values are converted into the Hounsfield scale, whereas the pixel values of an x-ray are proportional to the x-ray intensity.

Lossless compression A data compression technique which results in data being returned to its original form without any loss of information when it is decompressed. The decompressed file and the original file are identical. See Lossy compression.

Lossy compression This is a data compression technique; which results in data not being returned to its original form when it is decompressed. The benefit of using this technique is that it provides a high degree of compression, saving on storage space and transmission time over a network. See Lossless compression.

Low tide As the online storage reaches its working capacity or high tide point the system will remove the 'old' images.Tthe criteria for removal being defined by the system administrator. The images will be deleted until the online data store has reached a predefined low tide point, thus creating space for the acquisition of new images. See High tide.

LTA See Long Term Archive.

LTO See Linear Tape Open.

LUT See Look-up Table.