Free webp to jpg
EN
Image MIME Reference
FLIF

Free Lossless Image Format

image/flif
VS

SealedMedia Portable Network Graphics

image/vnd.sealed.png
Sealed-PNG

A complete technical comparison of Free Lossless Image Format 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 FLIF Sealed-PNG
Transparency (Alpha) Yes ✕ No
Animation Support Yes ✕ No
Progressive Loading Yes ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
Free Lossless Image Format
image/flif
Extension
.flif
Container FLIF Bitstream
Compression Lossless (MANIAC Entropy Coding)
Algorithm
MANIAC (Meta-Adaptive Near-zero Integer Arithmetic Coding)
Color Depth 1-bit to 16-bit (Per Channel), Grayscale, RGB, RGBA, CMYK
Developed by Jon Sneyers and Pieter Wuille (Cloudinary)
Released 2015
Magic Bytes
46 4C 49 46
Full FLIF 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 FLIF Sealed-PNG
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
FLIF

FLIF Strengths

  • Achieves some of the highest lossless compression ratios ever developed for raster images
  • Incredible progressive decoding allows an image to be highly recognizable even after only 5% of the file has been downloaded
  • Supports animations and complex alpha channels losslessly
Limitations
  • Officially abandoned in favor of JPEG XL
  • Zero native support in web browsers or standard operating system previewers
  • Encoding speed can be significantly slower than standard PNG or WebP compression
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

FLIF
Use FLIF when…
  • Archival of Uncompressed Image Assets
  • Bandwidth-Constrained Progressive Image Loading (Historical)
  • Medical and Scientific Imaging Storage
Sealed-PNG
Use Sealed-PNG when…
  • Enterprise Information Rights Management (IRM)
  • Secure Corporate Intellectual Property Distribution
  • Revocable Medical or Legal Imaging

More comparisons

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