PCX

PCX

PCX was one of the first file formats created to save raster images. It was created by ZSOFT and became the native file format on its Paintbrush application. It supported different colour modes such as 8-bit Greyscale and 16-bit RBG until it advanced and was able to save 24-bit true colour images. Nowadays, fax machines and optical scanners have no need to support PCX although some still do. PCX has long since been replaced by more advanced and flexible formats such as JPEG, GIF and PNG. Like TIFF, PCX was a lossless file format so master copies could be created and none of the quality was damaged.

Information was stored differently in PCX files. Things such as the bit depth, image resolution and colour palette were stored separately from the actual image information. This way it was easier for other computers to display the image with different software.  PCX files were compressed using run-length encoding which meant it stored three or more bytes of running colour into a two-byte pair. the most important of these two-byte pairs was used as a ‘flag’ to determine if the information was to represent an individual pixel or a cluster of pixels the same colour.

~ by Fizwidget on October 14, 2007.