Image MIME Reference
ACES
ACES Image Container File
image/aces
VS
Microsoft Document Imaging
image/vnd.ms-modi
MODI
A complete technical comparison of ACES Image Container File and Microsoft Document Imaging — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | ACES | MODI |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | ✕ No |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
ACES Image Container File
image/aces
Extension
.exr
Container
OpenEXR (SMPTE ST 2065-4)
Compression
Lossless / Uncompressed
Algorithm
PIZZIPRLEB44Uncompressed
Color Depth
16-bit (Half-float), 32-bit (Float)
Developed by
Academy of Motion Picture Arts and Sciences (AMPAS) / SMPTE
Released
2013
Magic Bytes
76 2F 31 01
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
Browser Support Comparison
| Browser | ACES | MODI |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
ACES
ACES Strengths
- Industry standard for high-end visual effects, compositing, and color grading
- Supports 16-bit half-float data, accurately capturing immense dynamic range without clipping
- Standardized by SMPTE (ST 2065-4) to guarantee universal color interoperability across different post-production facilities
Limitations
- Considerably larger file sizes than conventional consumer image formats
- Completely unsupported in web browsers and most standard desktop viewers
- Requires specialized compositing or color grading software to interpret and view the scene-linear data correctly
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
ACES
Use ACES when…
- Visual Effects (VFX)
- Digital Intermediate (DI)
- Color Grading
- Archival
MODI
Use MODI when…
- Legacy Scanned Document Archival
- Microsoft Office XP/2003/2007 Workflows
- Embedded OCR Text Storage