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Image MIME Reference
Sealed-PNG

SealedMedia Portable Network Graphics

image/vnd.sealed.png
VS

Sony SR2 Raw Image

image/x-sony-sr2
Sony-SR2

A complete technical comparison of SealedMedia Portable Network Graphics and Sony SR2 Raw Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature Sealed-PNG Sony-SR2
Transparency (Alpha) ✕ No ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support ✕ No Yes
EXIF Metadata ✕ No Yes
ICC Color Profile ✕ No Yes
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 →
Sony SR2 Raw Image
image/x-sony-sr2
Extension
.sr2
Container TIFF-based (Proprietary)
Compression Uncompressed / Sony Proprietary Lossless
Algorithm
NoneSony Proprietary Lossless
Color Depth 12-bit (Per Channel)
Developed by Sony Corporation
Released 2005
Magic Bytes
49 49 2A 00
Full Sony-SR2 reference →

Browser Support Comparison

Browser Sealed-PNG Sony-SR2
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
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
Sony-SR2

Sony-SR2 Strengths

  • Retains raw, unprocessed sensor data from legacy cameras, allowing modern raw processors to extract vastly superior image quality than what was possible in 2005
  • Utilizes a standard TIFF container structure, ensuring that community-maintained open-source decoding libraries (like LibRaw) can easily parse and maintain support for it indefinitely
Limitations
  • Completely obsolete format that has not been utilized in a new camera release in over a decade
  • MIME detection via magic bytes is unreliable due to TIFF header spoofing, requiring deeper EXIF inspection
  • Cannot be natively viewed in web browsers or standard operating system image viewers without specialized decoders

When to choose which format

Sealed-PNG
Use Sealed-PNG when…
  • Enterprise Information Rights Management (IRM)
  • Secure Corporate Intellectual Property Distribution
  • Revocable Medical or Legal Imaging
Sony-SR2
Use Sony-SR2 when…
  • Legacy Sony Cyber-shot/Alpha Photography
  • Non-destructive Image Post-Processing
  • Raw Imaging Archival

More comparisons

Sealed-PNG vs ACES → Sony-SR2 vs ACES → Sealed-PNG vs APNG → Sony-SR2 vs APNG → Sealed-PNG vs AVCI → Sony-SR2 vs AVCI → Sealed-PNG vs AVCS → Sony-SR2 vs AVCS → Sealed-PNG vs AVIF → Sony-SR2 vs AVIF → All comparisons →
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