PCX

PiCture eXchange

image/x-pcx Released 1985 · by ZSoft Corporation

The image/x-pcx MIME type represents the PiCture eXchange (PCX) image format. Developed by ZSoft Corporation in the mid-1980s for their PC Paintbrush software, PCX became one of the first widely accepted DOS-era graphics standards. It utilizes a very simple byte-oriented Run-Length Encoding (RLE) compression scheme, which required minimal CPU power to decode. This made it extraordinarily popular for 1990s MS-DOS video games (like DOOM, Duke Nukem 3D, and Quake) for storing textures and UI assets. While eventually superseded by more efficient formats like GIF, JPEG, and PNG, PCX remains historically significant in early PC graphics and retro game development.

Legacy & Raster Graphics Production Ready

Technical Specifications

MIME Type

image/x-pcx

Extensions

.pcx

Container

ZSoft Proprietary Header (128 bytes)

Compression

Run-Length Encoding (RLE)

Algorithms

ZSoft RLE

Color Depth

1-bit (Monochrome), 4-bit (16 colors), 8-bit (256 colors), 24-bit (True Color)

Metadata

None

Capabilities

Transparency

Animation

Progressive Loading

Alpha Channel

HDR Support

Official Specification

Aliases: image/pcxapplication/pcxapplication/x-pcx

Magic Bytes & HTTP Headers

File Signature (Magic Bytes)

0A (followed by version, e.g., 0A 05 01 08)

ASCII: \x0A

HTTP Headers

Content-Type: image/x-pcx

Content-Type: image/pcx

HTML Accept Attribute

accept="image/x-pcx, .pcx"

Browser Support Matrix

Browser	Status	Min Version
Chrome	Not Supported	—
Firefox	Not Supported	—
Safari	Not Supported	—
Edge	Not Supported	—
Internet Explorer	Not Supported	Legacy

Advantages & Limitations

Advantages

Incredibly simple RLE algorithm makes it very fast to decode, which was historically vital for early 3D video game engines
Retains crisp, lossless pixel data suitable for pixel art and interface assets
Well-documented and highly supported by older desktop publishing and image editing software

Limitations

Extremely inefficient compression by modern standards, producing large file sizes compared to PNG
Lacks modern imaging features such as alpha channel transparency, EXIF metadata, and color profiles
Zero support in web browsers; must be converted to PNG for web use

Developer Code Snippets

import magic
# Libmagic can easily detect the ZSoft PCX header
print(magic.from_file('graphic.pcx', mime=True)) # Outputs 'image/x-pcx' or 'image/pcx'

const fs = require('fs');
// Manually detecting the ZSoft PCX magic header
const buffer = Buffer.alloc(4);
const fd = fs.openSync('graphic.pcx', 'r');
fs.readSync(fd, buffer, 0, 4, 0);
fs.closeSync(fd);
// Check Manufacturer (0x0A), valid version (0-5), and encoding (0x01)
const isPCX = buffer[0] === 0x0A && buffer[1] <= 5 && buffer[2] === 0x01;
console.log('Is ZSoft PCX:', isPCX);

import (
    "bytes"
    "net/http"
)
// Native Go HTTP detection does not recognize PCX.
// You must explicitly check the first few bytes:
// isPCX := len(buf) >= 4 && buf[0] == 0x0A && buf[1] <= 0x05 && buf[2] == 0x01

$mime = mime_content_type('graphic.pcx');
echo $mime; // Standard PHP setups will return 'image/x-pcx' or 'image/pcx' depending on the system magic database

File Detection Steps

How to programmatically detect a image/x-pcx file by reading its raw bytes:

1 PCX files have a fixed 128-byte header.
2 Check the first byte (Offset 0). It must always be 0x0A (10), representing ZSoft as the manufacturer.
3 The second byte (Offset 1) indicates the version (0, 2, 3, 4, or 5).
4 The third byte (Offset 2) is the encoding method, which is almost universally 0x01 for RLE.
5 The fourth byte (Offset 3) represents the bits per pixel per plane (1, 2, 4, or 8).

Software Support

A

Adobe Photoshop

GIMP

ImageMagick

I

IrfanView / XnView

Conversion Tools

Share & Embed

Markdown Badge

[![PCX Format](https://freewebptojpg.com/mime/image/pcx/badge.svg)](https://freewebptojpg.com/mime/image/pcx)

Interactive iframe Widget

<iframe src="https://freewebptojpg.com/mime/image/pcx/embed" width="100%" height="280" style="border:1px solid #cbd5e1;border-radius:8px;" title="PCX Specs"></iframe>

JSON API

All data on this page is available as a free, open JSON API. Use it in your project, documentation, or tooling.

GET https://freewebptojpg.com/mime/image/pcx.json Open JSON

Free to use

No auth required

CORS enabled

Use from any domain

Cached 24h

Cache-Control headers set

Frequently Asked Questions

What is a PCX file?

A PCX file is a legacy raster image format created by ZSoft for its PC Paintbrush program. It was one of the most common image formats on DOS and early Windows systems before JPEG and PNG became standard.

Why did so many classic PC games use PCX files?

PCX files use a very simple Run-Length Encoding (RLE) compression method. In the early 1990s, when CPU cycles and memory were heavily constrained, game engines (like the Doom engine) could decompress and load PCX images incredibly fast compared to more complex formats.

How do I open a PCX file today?

Modern web browsers do not support PCX. To view or edit them, you must use image editing software like Adobe Photoshop, GIMP, or classic image viewers like IrfanView and XnView.