1985: ZSoft builds PC Paintbrush
The story of PCX begins in Marietta, Georgia, with a small software company called ZSoft Corporation. In 1984 ZSoft had developed a painting program called PC Paintbrush for IBM PCs — a clear clone of Apple's MacPaint, but for DOS machines with CGA and EGA graphics cards. PC Paintbrush needed a file format for saved images; the result was PCX, short for PC Paintbrush.
ZSoft's format was designed pragmatically for the hardware reality of 1985. PCs of the day had 256 KB to 640 KB of RAM, hard-disk storage was expensive (a 10 MB hard drive cost 1,500 US dollars), and floppy disks were limited to 360 KB. PCX had to store images as compactly as possible and be able to decode them in under 100 KB of memory.
The technical architecture
PCX is an extremely simple format. A PCX file consists of:
- A 128-byte header. Manufacturer ID (always 0x0A for ZSoft), format version, compression flag, bit depth, image dimensions, resolution in DPI, a color map for low bit depths, bytes per line, and the image-description plane count.
- Pixel data in RLE compression (run-length encoding).
- An optional 256-color palette at the end of the file (for PCX files with 8-bit indexing).
The RLE compression is primitive but effective. Each byte is examined bit by bit: if it begins with "11", the next 6 bits give the repeat count and the following byte gives the pixel value. If it begins with anything else, the byte itself is a pixel value. For images with lots of single-color areas — typical of the UI screenshots and pixel art of the era — this saves considerable space.
1986–1992: The de facto standard of the PC world
By the mid-1980s, PC Paintbrush was the dominant painting program in the DOS world. Microsoft did not yet have Windows; CorelDRAW had not been invented; Photoshop was a student project. PC Paintbrush dominated PC pixel work. ZSoft licensed the program to Microsoft, which integrated it as Paintbrush in Windows 1.0 (1985) and later as Paint in every subsequent version of Windows.
As a result, PCX became the standard image-exchange format of the early PC world. Printer drivers supported PCX, printing programs exported PCX, third-party software like Ventura Publisher and WordPerfect imported PCX. By 1992, practically every PC user had at least one PCX file on their hard drive.
1990: PCX 3.0 with 24-bit color depth
Originally PCX was designed for 1-bit (monochrome) and 4-bit (16 colors) — matching CGA and EGA hardware. With the arrival of VGA (1987, 256 colors), ZSoft extended the format to 8-bit indexed color. PCX 3.0 (1990) then also brought 24-bit true-color support, by storing the pixels in three separate plane layers (red, green, blue).
The plane-based architecture was unusual. Instead of storing pixels as interleaved RGB triples (R, G, B, R, G, B, …), PCX stores rows plane by plane (all the reds of a row, then all the greens, then all the blues). This was optimized for the hardware architecture of the EGA/VGA cards, but it made decoders more complex than necessary.
1993: GIF and JPEG arrive
PCX's decline began with the rise of two more modern formats. GIF (1987, see our GIF history) had better LZW compression and supported animation. JPEG (1992, see our JPEG history) offered dramatically smaller file sizes for photos. By the mid-1990s both formats had replaced PCX in most web and photo workflows.
ZSoft Corporation did not survive the format shift. The company was acquired by WordStar International in 1991 and merged in 1993 into the software suite Crayola Art Studio. PC Paintbrush itself continued running into the mid-1990s but was then discontinued — Microsoft Paint (which still carried ZSoft's code legacy) took over the market entirely.
PCX in the DOS games world
One stronghold where PCX survived especially long: DOS games. Classic adventure and RPG games like Wing Commander (1990), Master of Orion (1993), Doom (1993), Heroes of Might and Magic(1995), and Lands of Lore (1993) all stored their background images, UI sprites and cutscene frames as PCX. Game engines had simple PCX decoders built in that could decode directly from the .DAT archive files.
This DOS-games legacy keeps PCX present in retro-computing and pixel-art communities to this day. Anyone using a classic DOS adventure engine like DOSBox-X or ScummVM encounters PCX regularly. A modern indie-games scene (especially in the area of CGA/EGA aesthetics games) uses PCX to preserve retro authenticity.
PCX in 2026: archival status with devotees
In everyday web or photo work, PCX is irrelevant in 2026. Browsers can't open it, and no modern tool exports it by default. Adobe Photoshop dropped PCX import years ago (the last supported version was CS6 from 2012). GIMP still supports PCX via a plug-in; ImageMagick and FFmpeg read it as well.
But: devotee communities keep PCX alive. Pixel-art collections from the 1980s and 1990s are often archived as PCX. DOS-game modding tools like ALICE, IDA and various open-source decoders support PCX natively. Anyone pursuing a pixel-art renaissance with a claim to authenticity uses PCX as an asset format — much the way some vinyl lovers explicitly choose vinyl over CD.
When PCX is the right choice
- Retro DOS-game modding. When the original engine expects PCX, it's the mandatory choice.
- Pixel-art archives from the 1980s and 1990s. Authenticity-preserving storage.
- Embedded systems with legacy software. Industrial operator terminals and point-of-sale systems sometimes use PCX for embedded UI bitmaps.
When PCX is not ideal: anything that isn't specifically retro computing. For modern applications (web, mobile, photo), PNG, JPG, WebP and AVIF are the right choices. PCX no longer has any technical advantage — its compression is weak, its color depth limited, and its decoder complexity a historical artifact.
Sources
FileFormat.Info — ZSoft PCX · Wikipedia — PCX File Format · Internet Archive — PC Paintbrush 1.0 · DOSBox — Classic DOS games with PCX assets · ScummVM — Adventure engine with PCX support · ImageMagick — PCX Format Support · ZSoft Corporation, "PCX Programmer's Reference Manual", 1991.