Free webp to jpg
EN
Image MIME Reference
EMF

Windows Enhanced Metafile

image/x-emf
VS

SealedMedia Portable Network Graphics

image/vnd.sealed.png
Sealed-PNG

A complete technical comparison of Windows Enhanced Metafile 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 EMF Sealed-PNG
Transparency (Alpha) Yes ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support ✕ No ✕ No
EXIF Metadata ✕ No ✕ No
ICC Color Profile Yes ✕ No
Windows Enhanced Metafile
image/x-emf
Extension
.emf
Container Windows GDI/GDI+ Record Sequence
Compression Uncompressed (Binary Drawing Records)
Algorithm
None
Color Depth Vector (32-bit GDI/GDI+ Colors), Supports embedded 24-bit/32-bit bitmaps
Developed by Microsoft Corporation
Released 1993
Magic Bytes
01 00 00 00 (Header Type) ... 20 45 4D 46 (Signature at offset 40)
Full EMF 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 EMF Sealed-PNG
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✓
 ✕
EMF

EMF Strengths

  • Device independent, meaning it renders consistently across different monitors and printers regardless of resolution
  • Fully supports 32-bit precision and advanced GDI+ drawing commands, including alpha transparency and anti-aliasing (EMF+)
  • Native rendering within the Windows OS ensures fast performance and flawless fidelity in Microsoft Office applications
Limitations
  • Heavily tied to the Windows Graphics Device Interface API, making it notoriously difficult to parse perfectly on macOS or Linux
  • Completely unsupported by modern web standards; cannot be embedded in HTML without conversion to SVG
  • Security history: Like WMF, malicious drawing records can theoretically exploit vulnerabilities in older GDI parsers
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

EMF
Use EMF when…
  • Microsoft Office Vector Graphics and Clip Art
  • Windows Print Spooling (EMF Spool Files)
  • High-fidelity Vector Interchange on Windows
Sealed-PNG
Use Sealed-PNG when…
  • Enterprise Information Rights Management (IRM)
  • Secure Corporate Intellectual Property Distribution
  • Revocable Medical or Legal Imaging

More comparisons

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