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Image MIME Reference
AVIF

AV1 Image File Format

image/avif
VS

Windows Enhanced Metafile

image/x-emf
EMF

A complete technical comparison of AV1 Image File Format and Windows Enhanced Metafile — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

AVIF wins on browser support

Feature Support

Feature AVIF EMF
Transparency (Alpha) Yes Yes
Animation Support Yes ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes Yes
AV1 Image File Format
image/avif
Extension
.avif
Container HEIF / ISOBMFF
Compression AV1 Lossy / AV1 Lossless
Algorithm
AV1
Color Depth 8-bit, 10-bit, 12-bit
Developed by Alliance for Open Media (AOMedia)
Released 2019
Magic Bytes
XX XX XX XX 66 74 79 70 61 76 69 66
Full AVIF reference →
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 →

Browser Support Comparison

Browser AVIF EMF
Chrome Chrome
✓ 85+
 ✕
Firefox Firefox
✓ 93+
 ✕
Safari Safari
✓ 16+
 ✕
Edge Edge
✓ 121+
 ✕
IE IE (Legacy)
✕
✓
AVIF

AVIF Strengths

  • Best-in-class compression — typically 20–50% smaller than WebP at equivalent quality
  • Native HDR and wide color gamut (BT.2020) support
  • Supports 8, 10, and 12-bit color depth
Limitations
  • Encoding is highly CPU-intensive — significantly slower than JPEG or WebP
  • Requires Edge 121+ (not supported in earlier Edge versions)
  • Limited support in native desktop image viewers
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

When to choose which format

AVIF
Use AVIF when…
  • Next-Gen Websites
  • HDR Photography
  • High-Quality Web Images
EMF
Use EMF when…
  • Microsoft Office Vector Graphics and Clip Art
  • Windows Print Spooling (EMF Spool Files)
  • High-fidelity Vector Interchange on Windows

More comparisons

AVIF vs ACES → EMF vs ACES → AVIF vs APNG → EMF vs APNG → AVIF vs AVCI → EMF vs AVCI → AVIF vs AVCS → EMF vs AVCS → All comparisons →
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