Cartesian Perceptual Compression: Difference between revisions

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Latest revision as of 15:55, 11 June 2025

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{{Short description|Compressed image file format}}

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{{More citations|date=June 2025}}

'''Cartesian Perceptual Compression''' (abbreviated '''CPC''', with [[filename]] extension .cpc) is a proprietary [[image file|image]] [[file format]]. It was designed for high compression of black-and-white [[raster graphics|raster]] [[Documentdocument Imagingimaging]] for archival scans.

CPC is [[lossy]], has no [[lossless]] mode, and is restricted to bi-tonal images. The company which controls the patented format claims it is highly effective in the compression of text, black-and-white (halftone) [[photograph]]s, and line art. The format is intended for use in the web distribution of legal documents, [[blueprint|design plans]], and geographical plot maps.

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Viewing and converting documents in the CPC format currently requires the download of proprietary software. Although viewing CPC documents is free, as is converting CPC images to other formats, conversion to CPC format requires a purchase.

[[JSTOR]], a United States-basedStates–based online system for archiving academic journals, converted its online archives to CPC in 1997.<ref>{{cite press release |url=https://www.jstor.org/news/releases/cpc.html |title=JSTOR Incorporates Cartesian Perceptual Compression |work=[[JSTOR]] |date=1 November 1997 |archive-url=https://web.archive.org/web/20050206144808/https://www.jstor.org/news/releases/cpc.html |archive-date=6 February 2005 |access-date=11 June 2025 |url-status=dead}}</ref> The CPC files are used to reduce storage requirements for its online collection, but are temporarily converted on their servers to GIF for display, and to PDF for printing. JSTOR still scans to [[TIFF]] G4 and considers those files its preservation masters.

==See also==