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      <FormatDescription>The Graphics Interchange Format (GIF) is a raster image format developed by Compuserve, primarily for use on the internet. A GIF file begins with a Header section and a Logical Screen Descriptor section. This is followed by one or more Image sections, and the file is terminated by a Trailer. GIF supports bit depths between 1 and 8 bits (i.e. up to 256 colours) and supports features such as interlacing and transparency. Images are always stored using lossless LZW compression. GIF 89a introduced a number of new features, including a series of optional Control Extensions, which can be used to control the rendering of images within a file.</FormatDescription>
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      <ProvenanceName>Digital Preservation Department / The National Archives</ProvenanceName>
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        <DisplayText>Compuserve Incorporated, 1990, Graphics Interchange Format: Version 1989a</DisplayText>
        <DocumentType>Authoritative</DocumentType>
        <AvailabilityDescription>Public</AvailabilityDescription>
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        <PublicationDate>01 Jan 1990</PublicationDate>
        <TitleText>Graphics Interchange Format: Version 1989a</TitleText>
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          <PublisherCompoundName>Compuserve Incorporated</PublisherCompoundName>
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        <CompressionName>Lempel-Ziv-Welch</CompressionName>
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        <CompressionAliases>LZW</CompressionAliases>
        <CompressionFamilies>
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        <Description>The Lempel-Ziv-Welch compression algorithm was developed by Terry Welch in 1984, as a modification of the LZ78 compressor. It is a lossless technique which can be applied to almost any type of data, but is most commonly used for image compression. LZW compression is effective on images with colour depths from 1-bit (monochrome) to 24-bit (True Colour). LZW compression is encountered in a range of common graphics file formats, including TIFF and GIF.</Description>
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        <ReleaseDate>01 Jan 1984</ReleaseDate>
        <WithdrawnDate>
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        <CompressionDocumentation>Welch, T A, 1984, A technique for high performance data compression, IEEE Computer, 17: 6</CompressionDocumentation>
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