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Image MIME Reference
JPEG-XS-(HEIF)

JPEG XS Image (HEIF Container)

image/jxsi
VS

JPEG 2000 Part 2 (Extended)

image/jpx
JPX

A complete technical comparison of JPEG XS Image (HEIF Container) and JPEG 2000 Part 2 (Extended) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature JPEG-XS-(HEIF) JPX
Transparency (Alpha) Yes Yes
Animation Support ✕ No Yes
Progressive Loading ✕ No Yes
HDR Support Yes Yes
EXIF Metadata Yes Yes
ICC Color Profile Yes Yes
JPEG XS Image (HEIF Container)
image/jxsi
Extension
.jxsi.jxs.hif
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 69
Full JPEG-XS-(HEIF) reference →
JPEG 2000 Part 2 (Extended)
image/jpx
Extension
.jpx.jpf
Container ISOBMFF / JPX (ISO/IEC 15444-2)
Compression Lossy / Lossless
Algorithm
Discrete Wavelet Transform (DWT)
Color Depth 8-bit, 16-bit, 32-bit, 38-bit
Developed by Joint Photographic Experts Group (JPEG)
Released 2002
Magic Bytes
00 00 00 0C 6A 50 20 20 0D 0A 87 0A ... 66 74 79 70 6A 70 78 20
Full JPX reference →

Browser Support Comparison

Browser JPEG-XS-(HEIF) JPX
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
JPEG-XS-(HEIF)

JPEG-XS-(HEIF) Strengths

  • Provides sub-millisecond encoding and decoding latency while retaining visually lossless quality
  • Brings the extensive metadata, EXIF, XMP, and color-profiling capabilities of the HEIF container to JPEG XS
  • Allows grouping of multiple high-quality JPEG XS frames into a single collection file
Limitations
  • Zero web browser compatibility, limiting it entirely to professional and industrial hardware workflows
  • Extremely niche adoption compared to standard HEVC-based HEIC or raw JPEG XS codestreams
  • Requires custom parsing logic to extract the JPEG XS codestream from the HEIF boxes
JPX

JPX Strengths

  • Removes the color space limitations of baseline JP2, adding native support for CMYK, CIE Lab, and custom vendor color spaces
  • Supports multiple codestreams in a single file, allowing for rich compositing and animation
  • Enables fragmented files where image data and metadata can reside in separate physical files via data references
Limitations
  • Extremely complex specification makes full software implementation rare, leading to compatibility issues
  • Zero web browser support, rendering it unsuitable for public internet distribution
  • Often overkill for standard imaging tasks where baseline JP2 or modern alternatives like AVIF suffice

When to choose which format

JPEG-XS-(HEIF)
Use JPEG-XS-(HEIF) when…
  • Live Broadcast Infrastructure
  • Medical Imaging & Archival
  • Video over IP Networks
  • Automotive & Drone Systems
JPX
Use JPX when…
  • Prepress & Commercial Printing (CMYK)
  • Geospatial Data
  • Archival Preservation
  • Medical Imaging

More comparisons

JPEG-XS-(HEIF) vs ACES → JPX vs ACES → JPEG-XS-(HEIF) vs APNG → JPX vs APNG → JPEG-XS-(HEIF) vs AVCI → JPX vs AVCI → JPEG-XS-(HEIF) vs AVCS → JPX vs AVCS → JPEG-XS-(HEIF) vs AVIF → JPX vs AVIF → All comparisons →
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