Free webp to jpg
EN
Image MIME Reference
JPEG-XR

JPEG XR (HD Photo)

image/vnd.ms-photo
VS

X Pixmap

image/x-xpixmap
XPM

A complete technical comparison of JPEG XR (HD Photo) and X Pixmap — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature JPEG-XR XPM
Transparency (Alpha) Yes Yes
Animation Support ✕ No ✕ No
Progressive Loading Yes ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
JPEG XR (HD Photo)
image/vnd.ms-photo
Extension
.jxr.wdp.hdp
Container TIFF-like Image File Directory (IFD)
Compression Lossy (Lapped Bi-orthogonal Transform) / Lossless
Algorithm
Lapped Bi-orthogonal Transform (LBT)
Color Depth 8-bit (Grayscale, RGB, CMYK), 16-bit, 32-bit Floating Point (HDR)
Developed by Microsoft Corporation (later Joint Photographic Experts Group)
Released 2006
Magic Bytes
49 49 BC 01
Full JPEG-XR reference →
X Pixmap
image/x-xpixmap
Extension
.xpm
Container C Source Code Header (.c / .h)
Compression Uncompressed (Source Code)
Algorithm
None
Color Depth Indexed Color (Custom Palette with RGB and Alpha 'None')
Developed by Daniel Dardailler and Colas Nahaboo (Bull / X Consortium)
Released 1989
Magic Bytes
2F 2A 20 58 50 4D 20 2A 2F (ASCII '/* XPM */')
Full XPM reference →

Browser Support Comparison

Browser JPEG-XR XPM
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✓
✓
JPEG-XR

JPEG-XR Strengths

  • Excellent support for 16-bit and 32-bit floating-point HDR images without massive file size bloat
  • Native support for alpha transparency, which standard JPEG fundamentally lacks
  • Computational complexity for decoding/encoding is relatively low, making it hardware-friendly
Limitations
  • Suffered a complete failure of adoption in the web browser market outside of Microsoft's ecosystem
  • Fully superseded by modern, open formats like WebP, AVIF, and JPEG XL which offer better compression and universal browser support
  • Multiple file extensions (.wdp, .hdp, .jxr) and MIME types cause confusion and parsing fragmentation
XPM

XPM Strengths

  • Can be compiled directly into C or C++ source code without requiring an external asset loading mechanism
  • Human-readable palette mapping allows developers to inspect, modify, or hand-craft icons directly within a text editor
  • Native support for color palettes and transparency via the 'None' keyword
Limitations
  • Extremely inefficient storage structure for large images, resulting in massive file bloat compared to binary formats like PNG
  • Completely obsolete and unsupported in modern web browsers
  • Parsing overhead requires compiling or interpreting text-based color tables at runtime

When to choose which format

JPEG-XR
Use JPEG-XR when…
  • Legacy Windows Desktop Backgrounds
  • XPS (XML Paper Specification) Documents
  • Early High Dynamic Range (HDR) Photography
  • DirectX Textures
XPM
Use XPM when…
  • X Window System (X11) Application Icons and Cursors
  • Embedded C/C++ Firmware Color UI Assets
  • Early Linux Desktop Environment Themes

More comparisons

JPEG-XR vs ACES → XPM vs ACES → JPEG-XR vs APNG → XPM vs APNG → JPEG-XR vs AVCI → XPM vs AVCI → JPEG-XR vs AVCS → XPM vs AVCS → JPEG-XR vs AVIF → XPM vs AVIF → All comparisons →
Share this comparison