CPC (Cartesian Perceptual Compression) algorithm is designed for compressing 1-bit raster images, such as black-and-white photographs and line art; often used for compressing monochrome design layouts, legal documents, and other types of scanned text files.

To View files in IE install the ActiveX plugin from
http://www.cartesianinc.com/Products/CPCViewAX/

To convert CPC files into JPG use the command line tool CPCTool-523-Win32-X86.zip
source.cpc -O destination.jpg
For more switched run CPCTool without any parameters.