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Image MIME Reference
JPEG-XR-(HEIF)

JPEG XR Image (HEIF Container)

image/jxra
VS

SealedMedia Portable Network Graphics

image/vnd.sealed.png
Sealed-PNG

A complete technical comparison of JPEG XR Image (HEIF Container) and SealedMedia Portable Network Graphics — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature JPEG-XR-(HEIF) Sealed-PNG
Transparency (Alpha) Yes ✕ No
Animation Support ✕ No ✕ No
Progressive Loading Yes ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
JPEG XR Image (HEIF Container)
image/jxra
Extension
.jxra
Container HEIF / ISOBMFF (ISO/IEC 23008-12 / Annex F of ITU-T T.832)
Compression Lossy / Lossless
Algorithm
JPEG XR (Lapped Biorthogonal Transform)
Color Depth 8-bit, 16-bit, 32-bit (Float)
Developed by ISO/IEC JTC 1 / ITU-T
Released 2019
Magic Bytes
XX XX XX XX 66 74 79 70 6A 78 72 41
Full JPEG-XR-(HEIF) reference →
SealedMedia Portable Network Graphics
image/vnd.sealed.png
Extension
.spng.sealed-png
Container SealedMedia / Oracle IRM Wrapper
Compression Encrypted Payload (Deflate)
Algorithm
AES EncryptionDeflate (Internal PNG payload)
Color Depth Encrypted Payload
Developed by SealedMedia (Acquired by Oracle Corporation)
Released Late 1990s / Early 2000s
Magic Bytes
Unknown (Proprietary SealedMedia Container)
Full Sealed-PNG reference →

Browser Support Comparison

Browser JPEG-XR-(HEIF) Sealed-PNG
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
JPEG-XR-(HEIF)

JPEG-XR-(HEIF) Strengths

  • Combines the deep color (32-bit float) and mathematically lossless compression of JPEG XR with the robust metadata architecture of HEIF
  • Allows grouping multiple images, exposure brackets, or focal stacks into a single file collection
Limitations
  • Practically non-existent software and operating system support compared to standard HEIC or legacy JPEG XR (.jxr)
  • Zero web browser support, rendering it entirely unsuitable for public web deployment
  • Eclipsed by modern standards like AVIF and JPEG XL which offer superior compression with much broader industry backing
Sealed-PNG

Sealed-PNG Strengths

  • Provided absolute control over intellectual property, allowing enterprise administrators to instantly revoke viewing rights of a local file globally
  • Detailed audit trails tracked exactly who opened the image, when, and from what IP address
Limitations
  • Completely proprietary and relies on a central authentication server; if the server goes offline, the image is permanently inaccessible
  • No support in modern operating systems, web browsers, or standard image editing software without installing heavy enterprise DRM clients
  • Oracle effectively deprecated the IRM product line, leaving legacy sealed documents difficult to recover

When to choose which format

JPEG-XR-(HEIF)
Use JPEG-XR-(HEIF) when…
  • Specialized Archival
  • Experimental Imaging Workflows
  • High Dynamic Range (HDR) Imaging
Sealed-PNG
Use Sealed-PNG when…
  • Enterprise Information Rights Management (IRM)
  • Secure Corporate Intellectual Property Distribution
  • Revocable Medical or Legal Imaging

More comparisons

JPEG-XR-(HEIF) vs ACES → Sealed-PNG vs ACES → JPEG-XR-(HEIF) vs APNG → Sealed-PNG vs APNG → JPEG-XR-(HEIF) vs AVCI → Sealed-PNG vs AVCI → JPEG-XR-(HEIF) vs AVCS → Sealed-PNG vs AVCS → JPEG-XR-(HEIF) vs AVIF → Sealed-PNG vs AVIF → All comparisons →
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