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Image MIME Reference
AVIF

AV1 Image File Format

image/avif
VS

Microsoft Document Imaging

image/vnd.ms-modi
MODI

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

AVIF wins on browser support

Feature Support

Feature AVIF MODI
Transparency (Alpha) Yes ✕ No
Animation Support Yes ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
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 →
Microsoft Document Imaging
image/vnd.ms-modi
Extension
.mdi
Container TIFF Variant
Compression LZW / Proprietary MS Compression
Algorithm
LZW (Modified)
Color Depth 1-bit (Monochrome), 8-bit (Grayscale), 24-bit (RGB)
Developed by Microsoft Corporation
Released 2001
Magic Bytes
49 49 2A 00
Full MODI reference →

Browser Support Comparison

Browser AVIF MODI
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
MODI

MODI Strengths

  • Historically provided an excellent all-in-one scanned document format with built-in OCR and annotations before PDF editing became universally accessible
  • Tightly integrated with Microsoft Office and SharePoint workflows in the early 2000s
Limitations
  • Completely proprietary and obsolete; Microsoft abandoned it in favor of standard TIFF and PDF
  • Causes widespread identification conflicts since its file signature is identical to a standard TIFF
  • Extremely difficult to open on modern operating systems without relying on third-party conversion utilities

When to choose which format

AVIF
Use AVIF when…
  • Next-Gen Websites
  • HDR Photography
  • High-Quality Web Images
MODI
Use MODI when…
  • Legacy Scanned Document Archival
  • Microsoft Office XP/2003/2007 Workflows
  • Embedded OCR Text Storage

More comparisons

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