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Image MIME Reference
Pentax-PEF

Pentax Electronic File

image/x-pentax-pef
VS

SealedMedia Portable Network Graphics

image/vnd.sealed.png
Sealed-PNG

A complete technical comparison of Pentax Electronic File 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 Pentax-PEF Sealed-PNG
Transparency (Alpha) ✕ No ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
Pentax Electronic File
image/x-pentax-pef
Extension
.pef
Container TIFF-based (Proprietary)
Compression Uncompressed / Proprietary Lossless
Algorithm
NonePentax Proprietary Lossless
Color Depth 12-bit (Per Channel), 14-bit (Per Channel)
Developed by Pentax (now Ricoh Imaging Company, Ltd.)
Released 2003
Magic Bytes
49 49 2A 00 (Little-endian) or 4D 4D 00 2A (Big-endian)
Full Pentax-PEF 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 Pentax-PEF Sealed-PNG
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
Pentax-PEF

Pentax-PEF Strengths

  • Retains absolute maximum sensor data, enabling massive shadow recovery and highlight protection compared to compressed in-camera JPEGs
  • White balance and sharpening are saved as metadata instructions rather than 'baked in', meaning they can be perfectly adjusted in post-production
  • Utilizes the standard TIFF container structure, making it relatively straightforward for open-source software like LibRaw to parse
Limitations
  • Proprietary format requires continuous updates to third-party processing software whenever Pentax releases a new camera model (unlike the open DNG format)
  • Produces very large file sizes compared to standard web formats
  • Cannot be directly embedded into web pages or used in standard HTML/CSS contexts
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

Pentax-PEF
Use Pentax-PEF when…
  • Professional Digital Photography
  • Non-destructive Image Post-Processing
  • Pentax Camera Archival
Sealed-PNG
Use Sealed-PNG when…
  • Enterprise Information Rights Management (IRM)
  • Secure Corporate Intellectual Property Distribution
  • Revocable Medical or Legal Imaging

More comparisons

Pentax-PEF vs ACES → Sealed-PNG vs ACES → Pentax-PEF vs APNG → Sealed-PNG vs APNG → Pentax-PEF vs AVCI → Sealed-PNG vs AVCI → Pentax-PEF vs AVCS → Sealed-PNG vs AVCS → Pentax-PEF vs AVIF → Sealed-PNG vs AVIF → All comparisons →
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