MODI

Microsoft Document Imaging

image/vnd.ms-modi Released 2001 · by Microsoft Corporation

The image/vnd.ms-modi MIME type represents the Microsoft Document Imaging (MDI) format. Introduced with Microsoft Office XP (2001) and used through Office 2007, MDI is a proprietary, closed-source variant of the TIFF format. It was designed specifically to store scanned documents, supporting multi-page layouts, annotations, and embedded Optical Character Recognition (OCR) text generated by the Microsoft Office Document Imaging application. Microsoft officially deprecated and removed support for the format starting with Office 2010, transitioning users to TIFF and PDF.

Legacy & Proprietary Production Ready

Technical Specifications

MIME Type

image/vnd.ms-modi

Extensions

.mdi

Container

TIFF Variant

Compression

LZW & Proprietary MS Compression

Algorithms

LZW (Modified)

Color Depth

1-bit (Monochrome), 8-bit (Grayscale), 24-bit (RGB)

Metadata

None

Capabilities

Transparency

Animation

Progressive Loading

Alpha Channel

HDR Support

Official Specification

Aliases: image/mdi

Magic Bytes & HTTP Headers

File Signature (Magic Bytes)

49 49 2A 00

ASCII: II*\x00

HTTP Headers

Content-Type: image/vnd.ms-modi

HTML Accept Attribute

accept="image/vnd.ms-modi, .mdi"

Browser Support Matrix

Browser	Status	Min Version
Chrome	Not Supported	—
Firefox	Not Supported	—
Safari	Not Supported	—
Edge	Not Supported	—
Internet Explorer	Not Supported	Legacy

Advantages & Limitations

Advantages

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

Developer Code Snippets

import magic
# Libmagic will identify MDI files as standard TIFFs because they share the identical 49 49 2A 00 header
print(magic.from_file('scanned_doc.mdi', mime=True)) # Outputs 'image/tiff'

const FileType = require('file-type');
const type = await FileType.fromFile('scanned_doc.mdi');
console.log(type.mime); // Often outputs 'image/tiff'. You must correlate with the .mdi extension.

import (
    "bytes"
    "net/http"
)
// http.DetectContentType reads the TIFF magic bytes and returns 'image/tiff'. 
// To distinguish MDI, you need a custom TIFF parser to search for MS proprietary IFD tags.

$mime = mime_content_type('scanned_doc.mdi');
echo $mime; // Standard PHP environments will resolve this to 'image/tiff'

File Detection Steps

How to programmatically detect a image/vnd.ms-modi file by reading its raw bytes:

1 Check the first 4 bytes for the standard TIFF little-endian magic number: 49 49 2A 00.
2 Because MDI shares its header with standard TIFF files, a basic magic byte sniff will falsely identify it as 'image/tiff'.
3 To properly identify an MDI file, you must parse the TIFF Image File Directory (IFD) and check for proprietary Microsoft tags (such as tag 34019, which indicates the presence of an MDI-specific stream).

Software Support

M

Microsoft Office Document Imaging (Legacy)

M

MDI2TIF Converter

B

Bugysoft MDI Viewer

Conversion Tools

Share & Embed

Markdown Badge

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Interactive iframe Widget

<iframe src="https://freewebptojpg.com/mime/image/modi/embed" width="100%" height="280" style="border:1px solid #cbd5e1;border-radius:8px;" title="MODI Specs"></iframe>

JSON API

All data on this page is available as a free, open JSON API. Use it in your project, documentation, or tooling.

GET https://freewebptojpg.com/mime/image/modi.json Open JSON

Free to use

No auth required

CORS enabled

Use from any domain

Cached 24h

Cache-Control headers set

Frequently Asked Questions

What is an MDI file?

An MDI (Microsoft Document Imaging) file is a proprietary document format created by legacy versions of Microsoft Office to store scanned documents, complete with multi-page support, annotations, and searchable OCR text.

How do I open an .mdi file on Windows 10 or 11?

Modern versions of Windows and Microsoft Office no longer support MDI files natively. To open them, you must use a third-party MDI viewer, an MDI-to-TIFF conversion tool, or manually install the legacy MDI viewer from an old Office 2007 installation disk (via SharePoint Designer 2007).

Is an MDI file just a TIFF file?

Essentially, yes. MDI is a highly customized variant of the standard TIFF format. It uses the exact same magic bytes as a little-endian TIFF file, but includes proprietary Microsoft tags to store OCR data and annotations that standard TIFF viewers cannot parse.