ZSoft Paintbrush .PCX File Description


The ZSoft Paintbrush filter imports and exports ZSoft Paintbrush bitmaps.


File Description

The .PCX is an image file format developed by the ZSoft Corporation of Georgia, USA. It was the native file format for PC Paintbrush (PCX = "PC Paintbrush Exchange") and became one of the first widely accepted DOS image standards, although its use has since been succeeded by more sophisticated image formats such as GIF, JPEG, and PNG. PCX is used in Microsoft Windows and Windows-based products but has found wide acceptance mainly in the MS-DOS world. It is mainly an exchange and storage format. PCX is a format in wide use, which is quick and easy to read and decompress. It lacks, however, a superior compression scheme, making it unsuitable for the storage of deep-pixel images.


The .PCX file is a device-independent raster image format; the file header stores information about the display hardware (screen resolution, color depth and palette information, and bit planes) separately from the actual image information, allowing the image to be properly transferred and dsiplayed on computer systems with different hardware. PCX files commonly store palette-indexed images ranging from 2 or 4 colors to 16 and 256 colors, although the format has been extended to record true-color (24-bit) images as well.


File Header

PCX files are organized into three major sections: the header, the image data, and the color palette. The color palette normally contains entries for 256 colors and is associated with the VGA display adapter. This VGA color palette is only found in later versions of the PCX image file format.


The PCX file header contains an identifier byte (value 10), a version number, image dimensions, a 16 color palette, number color planes and the bit depth of each plane. While the file header could describe a wide variety of image formats, many are not of practical use. Convention has limited the supported combinations of plane count and bit depth to match specific PC display hardware. Many image editing programs will not read PCX files which do not match one of these conventions. Table A shows the most commonly supported combinations.


The header also contains a value for compression method. All PCX files are written with the same compression scheme and this value is always 1. No other values have been defined and there are no uncompressed PCX files.


PCX version numbers range from 0 to 5, though the file format does not change between versions.


The header is always 128 bytes long though only 74 bytes are used. The rest of the 128 bytes is padded and the image data always begins 128 bytes after the start of the file.


File Name Extensions



Format(s) Supported for Import

device-independent bitmap; 1, 4, 8, 24 bit per pixel


Format(s) Supported for Export

device-independent bitmap; 8, 24 bit per pixel


Import Method

Choose the File | Import command.


Export Method

Choose the File | Export command or select an image module and choose the File | Save Data command.


Export Options

Specify the export options in the Export Options dialog.



See Also

File Format Chart

Export Options

File | Import

File | Save Data

File | Export