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Image MIME Reference
JPEG-XS-Sequence

JPEG XS Image Sequence (HEIF Container)

image/jxss
VS

X Pixmap

image/x-xpixmap
XPM

A complete technical comparison of JPEG XS Image Sequence (HEIF Container) and X Pixmap — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature JPEG-XS-Sequence XPM
Transparency (Alpha) Yes Yes
Animation Support Yes ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
JPEG XS Image Sequence (HEIF Container)
image/jxss
Extension
.jxss.jxs
Container HEIF / ISOBMFF (ISO/IEC 23008-12)
Compression Lossy (Visually Lossless) / Mathematically Lossless
Algorithm
JPEG XS (ISO/IEC 21122-1)
Color Depth 8-bit, 10-bit, 12-bit, 14-bit, 16-bit
Developed by Joint Photographic Experts Group (JPEG)
Released 2019
Magic Bytes
XX XX XX XX 66 74 79 70 6A 78 73 73
Full JPEG-XS-Sequence 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-XS-Sequence XPM
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕
✓
JPEG-XS-Sequence

JPEG-XS-Sequence Strengths

  • Provides sub-millisecond encoding and decoding latency across a video sequence while retaining visually lossless quality
  • Leverages the robust ISOBMFF track structures for accurate frame timing, audio synchronization, and metadata handling
  • Optimized for professional video production and IP broadcasting workflows
Limitations
  • Zero web browser compatibility, limiting its use entirely to professional and industrial hardware workflows
  • Compression ratios are significantly lower than consumer video codecs like HEVC or AV1
  • Extremely niche format that requires highly specialized broadcast hardware or custom software libraries to process
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-XS-Sequence
Use JPEG-XS-Sequence when…
  • Live Broadcast Video Snippets
  • Medical Imaging Sequences
  • HDR Burst Photography Archiving
  • Automotive & Drone Video Storage
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-XS-Sequence vs ACES → XPM vs ACES → JPEG-XS-Sequence vs APNG → XPM vs APNG → JPEG-XS-Sequence vs AVCI → XPM vs AVCI → JPEG-XS-Sequence vs AVCS → XPM vs AVCS → JPEG-XS-Sequence vs AVIF → XPM vs AVIF → All comparisons →
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