Cartesian Perceptual Compression
Encyclopedia
Cartesian Perceptual Compression (abbreviated CPC, with filename
extension .cpc) is a proprietary image file format
. It was designed for high compression of black-and-white raster
Document Imaging
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, design plans
, and geographical plot maps.
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-based online system for archiving academic journals, converted its online archives to CPC in 1997. 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.
Filename
The filename is metadata about a file; a string used to uniquely identify a file stored on the file system. Different file systems impose different restrictions on length and allowed characters on filenames.A filename includes one or more of these components:...
extension .cpc) is a proprietary image file format
File format
A file format is a particular way that information is encoded for storage in a computer file.Since a disk drive, or indeed any computer storage, can store only bits, the computer must have some way of converting information to 0s and 1s and vice-versa. There are different kinds of formats for...
. It was designed for high compression of black-and-white raster
Raster graphics
In computer graphics, a raster graphics image, or bitmap, is a data structure representing a generally rectangular grid of pixels, or points of color, viewable via a monitor, paper, or other display medium...
Document Imaging
Document imaging
Document imaging is an information technology category for systems capable of replicating documents commonly used in business. Document imaging systems can take many forms including microfilm, on demand printers, facsimile machines, copiers, multifunction printers, document scanners, computer...
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
Photograph
A photograph is an image created by light falling on a light-sensitive surface, usually photographic film or an electronic imager such as a CCD or a CMOS chip. Most photographs are created using a camera, which uses a lens to focus the scene's visible wavelengths of light into a reproduction of...
s, and line art. The format is intended for use in the web distribution of legal documents, design plans
Blueprint
A blueprint is a type of paper-based reproduction usually of a technical drawing, documenting an architecture or an engineering design. More generally, the term "blueprint" has come to be used to refer to any detailed plan....
, and geographical plot maps.
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
JSTOR
JSTOR is an online system for archiving academic journals, founded in 1995. It provides its member institutions full-text searches of digitized back issues of several hundred well-known journals, dating back to 1665 in the case of the Philosophical Transactions of the Royal Society...
, a United States-based online system for archiving academic journals, converted its online archives to CPC in 1997. 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.
External links
- The company's website Additional technical information about the format
- Library of Congress Description of feasibility of use by the LoC.
- RLG DigiNews Vol. 7 No. 2 Comparison of rivals to TIFF for Document Imaging purposes