PCX Format Guide

Available Conversions

Convert to PCX

About PCX Format

PCX (PiCture eXchange) is a raster image file format developed by ZSoft Corporation in 1985 as the native format for their PC Paintbrush graphics program, one of the first popular paint applications for IBM PC compatibles running MS-DOS. PCX was among the earliest standardized image formats for the PC platform and became widely adopted throughout the late 1980s and early 1990s as the default image format for DOS-based software, early Windows applications, and desktop publishing tools. The format uses Run-Length Encoding (RLE) compression, a simple lossless algorithm that reduces file size by encoding consecutive identical pixel values as a single count-value pair, making it effective for images with large areas of uniform color but less efficient for photographic content with complex detail. PCX supports a range of color depths from 1-bit monochrome through 4-bit (16 colors) and 8-bit (256 colors) palettized modes to 24-bit true color, though it notably lacks support for alpha channel transparency. The file structure consists of a 128-byte header containing image dimensions, color depth, palette information, and DPI settings, followed by RLE-compressed scanline data organized by color plane.

History of PCX

The PCX format was created by ZSoft Corporation in 1985 in Marietta, Georgia, as the native file format for PC Paintbrush, a paint and image editing program designed for the IBM PC and compatible computers. PC Paintbrush was one of the first graphics applications available for the DOS platform and was frequently bundled with mice, scanners, and graphics cards during the late 1980s, which helped establish PCX as the de facto image format on IBM PCs. The format went through several version revisions: version 0 supported monochrome images, version 2 added EGA 16-color support with palette information, version 3 introduced 256-color mode without embedded palette data, version 4 was reserved for internal use, and version 5 (the most common) added 256-color support with the palette appended at the end of the file and 24-bit true color via multiple color planes. When Microsoft released Windows 3.0 in 1990 with its own Paintbrush application (a licensed version of ZSoft's software), PCX support was built directly into the operating system, further cementing its position as a standard PC image format. Throughout the early 1990s, PCX was the most commonly used image format in DOS gaming, desktop publishing, fax software, and early multimedia applications. However, the emergence of BMP as Windows' native format, the introduction of GIF for online graphics, and especially the standardization of PNG in 1996 gradually displaced PCX from mainstream use. By the late 1990s, PCX had largely been superseded by more capable formats, though it continued to appear in legacy systems, retro computing, and vintage software collections.

Key Features and Uses

PCX's design reflects the hardware constraints and software practices of 1980s personal computing. The format's RLE compression operates on individual scanlines, encoding each row of pixels independently, which allows partial image decoding and makes the format straightforward to implement on the limited computing resources of early PCs. The 128-byte fixed-size header provides quick access to image metadata including width, height, bits per pixel, number of color planes, horizontal and vertical DPI, and a 16-color EGA palette, enabling applications to determine image properties without parsing the entire file. For 256-color images, PCX version 5 appends a 768-byte palette at the end of the file (256 RGB triplets), preceded by a 0x0C marker byte. The color plane architecture supports multiple bit planes that can be combined to represent different color depths: a single plane with 8 bits per pixel for 256 colors, or three planes with 8 bits each for 24-bit true color. PCX files were commonly used for sprite sheets, game textures, scanned documents, clipart collections, and screen captures in DOS applications. The format was supported by virtually every DOS-era image viewer, paint program, and desktop publishing application, including programs like Deluxe Paint, Graphics Workshop, and early versions of CorelDRAW.

Common Applications

In its era, PCX was the dominant image format for a wide range of PC applications. DOS game developers used PCX extensively for storing game graphics, sprites, textures, and background art, as the format was simple to parse and the RLE decompression was fast enough for real-time loading even on early Intel 286 and 386 processors. Classic DOS games such as Commander Keen, Duke Nukem, and numerous shareware titles stored their visual assets in PCX format. Desktop publishing software including PageMaker, Ventura Publisher, and early QuarkXPress supported PCX for importing scanned images and clipart. Fax software like WinFax and various OCR (Optical Character Recognition) applications used PCX for storing scanned document pages, particularly in monochrome 1-bit mode where RLE compression was highly effective. Scanner software bundled with early flatbed scanners from HP, Microtek, and Logitech typically saved scanned images in PCX format. Today, PCX files are primarily encountered when working with legacy systems, converting vintage software assets, preserving retro game content, or processing archived documents from the 1980s and 1990s. Retro computing enthusiasts and game preservation communities regularly work with PCX files when restoring or modding classic DOS-era games. Converting PCX to modern formats like PNG, JPG, or WebP is necessary for using these legacy images in contemporary applications, websites, or digital archives.

Advantages and Disadvantages