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fdd000333.xml
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fdd000333.xml
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<?xml version="1.0" encoding="UTF-8"?>
<fdd:FDD id="fdd000333" titleName="JPEG DCT Compression Encoding, Progressive" shortName="JPEG_DCT_PRG" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:fdd="http://www.loc.gov/preservation/digital/formats/schemas/fdd/v1" xsi:schemaLocation="http://www.loc.gov/preservation/digital/formats/schemas/fdd/v1 http://www.loc.gov/preservation/digital/formats/schemas/fdd/v1/fdd-v1-2.xsd">
<fdd:properties>
<fdd:gdfrGenreSelection>
<fdd:gdfrGenre>still-image</fdd:gdfrGenre>
</fdd:gdfrGenreSelection>
<fdd:formatCategories>
<fdd:category>encoding</fdd:category>
</fdd:formatCategories>
<fdd:gdfrComposition>unitary</fdd:gdfrComposition>
<fdd:gdfrForm>binary</fdd:gdfrForm>
<fdd:gdfrBasis>sampled</fdd:gdfrBasis>
<fdd:updates>
<fdd:date>2012-01-26</fdd:date>
</fdd:updates>
<fdd:draftStatus>Full</fdd:draftStatus>
</fdd:properties>
<fdd:identificationAndDescription>
<fdd:fullName>ISO/IEC 10918-1:1994. Information technology -- Digital compression and coding of continuous-tone still images, progressive DCT-based (formal name); Progressive JPEG (common name)</fdd:fullName>
<fdd:keywords>
<fdd:keyword>raster image formats</fdd:keyword>
</fdd:keywords>
<fdd:description>Lossy compression encoding for full color and grayscale continuous-tone images that employs discrete cosine transforms (DCT) and other processes, and encodes similar-positioned coefficients of all 8-by-8-pixel Minimum Coded Unit (MCU) blocks in one action, followed by the next positioned coefficients of all blocks, etc. When a progressive image is decoded, "every other line" appears, displaying a top-to-bottom image relatively quickly; following this, the missing lines are filled in. The encoding and related matters are well described in the ISO specification and on Web sites like those cited in <a href="#useful">Useful references</a> in this description.</fdd:description>
<fdd:shortDescription>Lossy compression algorithm for full color and grayscale continuous-tone images that employs discrete cosine transforms (DCT) and other processes, and encodes similar-positioned coefficients of all blocks in one action, followed by the next positioned coefficients of all blocks, etc.</fdd:shortDescription>
<fdd:productionPhase>May be applied in initial-state picture creation; often used for middle- and final-state archiving or end-user delivery. </fdd:productionPhase>
<fdd:relationships>
<fdd:relationship>
<fdd:typeOfRelationship>Subtype of</fdd:typeOfRelationship>
<fdd:relatedTo>
<fdd:id>fdd000017</fdd:id>
<fdd:shortName>JPEG</fdd:shortName>
<fdd:titleName>JPEG Image Encoding Family</fdd:titleName>
</fdd:relatedTo>
</fdd:relationship>
<fdd:relationship>
<fdd:typeOfRelationship>Used by</fdd:typeOfRelationship>
<fdd:relatedTo>
<fdd:id>fdd000618</fdd:id>
<fdd:shortName>JFIF_Family</fdd:shortName>
<fdd:titleName>JPEG File Interchange Format Family</fdd:titleName>
</fdd:relatedTo>
</fdd:relationship>
<fdd:relationship>
<fdd:typeOfRelationship>Used by</fdd:typeOfRelationship>
<fdd:relatedTo>
<fdd:id>fdd000018</fdd:id>
<fdd:shortName>JFIF_1_02</fdd:shortName>
<fdd:titleName>JFIF JPEG File Interchange Format, Version 1.02</fdd:titleName>
</fdd:relatedTo>
</fdd:relationship>
<fdd:relationship>
<fdd:typeOfRelationship>Used by</fdd:typeOfRelationship>
<fdd:comment>JFIF File Interchange Format, Versions 1.00 and 1.01, not described at this Web site at this time</fdd:comment>
</fdd:relationship>
<fdd:relationship>
<fdd:typeOfRelationship>Used by</fdd:typeOfRelationship>
<fdd:relatedTo>
<fdd:id>fdd000019</fdd:id>
<fdd:shortName>SPIFF</fdd:shortName>
<fdd:titleName>SPIFF Still Picture Interchange File Format</fdd:titleName>
</fdd:relatedTo>
</fdd:relationship>
<fdd:relationship>
<fdd:typeOfRelationship>Used by</fdd:typeOfRelationship>
<fdd:comment>JTIF File Format, a variant of TIFF, not described at this Web site at this time</fdd:comment>
</fdd:relationship>
</fdd:relationships>
</fdd:identificationAndDescription>
<fdd:localUse>
<fdd:experience>See <fddLink id="fdd000017">JPEG</fddLink>.</fdd:experience>
<fdd:preference>See <fddLink id="fdd000017">JPEG</fddLink>.</fdd:preference>
</fdd:localUse>
<fdd:sustainabilityFactors>
<fdd:disclosure>Fully disclosed. Developed by the Joint Photographic Experts Group (JPEG), formally known as ISO/IEC JTC 1/SC 29/WG 10.
</fdd:disclosure>
<fdd:documentation>ISO/IEC 10918-1:1994, Information technology -- Digital compression and coding of continuous-tone still images: Requirements and guidelines. Same as ITU-T Rec. T.81:1992.</fdd:documentation>
<fdd:adoption>Widely adopted.</fdd:adoption>
<fdd:licensingAndPatents>See <fddLink id="fdd000017">JPEG</fddLink>.</fdd:licensingAndPatents>
<fdd:transparency>Depends upon algorithms and tools to read; will require sophistication to build tools.
</fdd:transparency>
<fdd:selfDocumentation>See the file format descriptions for <fddLink id="fdd000018">JFIF_1_02</fddLink>, <fddLink id="fdd000019">SPIFF</fddLink>, and <fddLink id="fdd000147">JPEG_EXIF</fddLink>.
</fdd:selfDocumentation>
<fdd:externalDependencies>None.
</fdd:externalDependencies>
<fdd:techProtection>None.
</fdd:techProtection>
</fdd:sustainabilityFactors>
<fdd:qualityAndFunctionalityFactors>
<fdd:stillImageQF>
<fdd:normalImage>Good support.</fdd:normalImage>
<fdd:clarity>Good, considering that the source data is limited to 8-bits-per-channel. Quality varies according to the sophistication of the encoding and the degree of compression applied. Most commentators agree that, at the same compression ratios, discrete cosine tranforms (DCT) produce less clarity than discrete wavelet tranforms (DWT), used by <fddLink id="fdd000137">J2K</fddLink> (JPEG 2000) and other compression algorithms.</fdd:clarity>
<fdd:colorMaint>See the file format descriptions for <fddLink id="fdd000018">JFIF_1_02</fddLink>, <fddLink id="fdd000019">SPIFF</fddLink>, and <fddLink id="fdd000147">JPEG_EXIF</fddLink>.
</fdd:colorMaint>
<fdd:graphics>No support for vector graphics.</fdd:graphics>
<fdd:multispectral>See <fddLink id="fdd000017">JPEG</fddLink>.</fdd:multispectral>
<fdd:beyondImage>Not investigated for this format description.</fdd:beyondImage>
</fdd:stillImageQF>
</fdd:qualityAndFunctionalityFactors>
<fdd:fileTypeSignifiers>
<fdd:signifiersGroup>
<fdd:filenameExtension>
<fdd:sigValueNA>Not applicable.</fdd:sigValueNA>
<fdd:note>See <fddLink id="fdd000018">JFIF_1_02</fddLink>, <fddLink id="fdd000019">SPIFF</fddLink>, and <fddLink id="fdd000147">JPEG_EXIF</fddLink>.</fdd:note>
</fdd:filenameExtension>
<fdd:internetMediaType>
<fdd:sigValueNA>Not applicable.</fdd:sigValueNA>
<fdd:note>See <fddLink id="fdd000018">JFIF_1_02</fddLink>, <fddLink id="fdd000019">SPIFF</fddLink>, and <fddLink id="fdd000147">JPEG_EXIF</fddLink>.</fdd:note>
</fdd:internetMediaType>
<fdd:magicNumbers>
<fdd:sigValues>
<fdd:sigValue>Hex: 0xFF 0xD8</fdd:sigValue>
</fdd:sigValues>
<fdd:note>Start of Image (SOI) marker; see also <fddLink id="fdd000017">JPEG</fddLink>
</fdd:note>
</fdd:magicNumbers>
<fdd:other>
<fdd:tag>Indicator for profile, level, version, etc.</fdd:tag>
<fdd:values>
<fdd:sigValues>
<fdd:sigValue>Hex: 0xFFC2</fdd:sigValue>
</fdd:sigValues>
<fdd:note>Start of Frame (SOF) marker for progressive DCT; see also <fddLink id="fdd000017">JPEG</fddLink>
</fdd:note>
</fdd:values>
</fdd:other>
</fdd:signifiersGroup>
</fdd:fileTypeSignifiers>
<fdd:notes/>
<fdd:formatSpecifications>
<fdd:citations>
<fdd:citation>
<fdd:specReference>ISO/IEC 10918-1:1994. Information technology -- Digital compression and coding of continuous-tone still images: Requirements and guidelines</fdd:specReference>
</fdd:citation>
<fdd:citation>
<fdd:specReference>ITU-T Rec. T.81:1992. Information technology – Digital compression and coding of continuous-tone still images: Requirements and guidelines (same as ISO/IEC 10918-1)</fdd:specReference>
</fdd:citation>
</fdd:citations>
</fdd:formatSpecifications>
<fdd:usefulReferences>
<fdd:urls>
<fdd:url>
<fdd:urlReference>
<link>http://www.yuiblog.com/blog/2008/12/05/imageopt-4/</link>
<tag>Image Optimization, Part 4: Progressive JPEG…Hot or Not?</tag>
<comment>2008 blog by Stoyan Stefanov, compares progressive and baseline. (Blog was no longer available when checked in July 2021.)</comment>
</fdd:urlReference>
</fdd:url>
<fdd:url>
<fdd:urlGroup>
<fdd:intro>See also <fddLink id="fdd000017">JPEG</fddLink>.</fdd:intro>
</fdd:urlGroup>
</fdd:url>
</fdd:urls>
</fdd:usefulReferences>
</fdd:FDD>