What is the IMAGE file format?
An .image file is a classic Mac OS disk image created by ShrinkWrap, a disk image utility developed by Aladdin Systems - the company behind StuffIt compression. ShrinkWrap launched in 1994 for System 7 and later Mac OS releases, allowing users to create, mount, and distribute mountable disk images without physical media.
The format stores a sector-by-sector copy of a Mac floppy or hard disk partition - typically carrying an HFS or HFS+ volume - inside a proprietary ShrinkWrap container. The application could optionally apply StuffIt compression and 40-bit encryption to reduce image size and protect content. ShrinkWrap also supported Apple's DiskCopy 4.2 and NDIF (DiskCopy 6) image formats, so some .image files are internally NDIF containers.
Aladdin Systems acquired ShrinkWrap 2.1 (originally freeware) and commercialized versions 2.x through 3.5. The final release, ShrinkWrap 3.5 (1999), was discontinued when Mac OS X introduced the UDIF DMG format and built-in Disk Utility in 2001.
The .image extension for disk images is effectively obsolete today. Opening legacy .image files generally requires a classic Mac OS environment or an emulator such as Basilisk II. Apple Disk Utility can open some .image files when they conform to DiskCopy 4.2 or NDIF standards, but ShrinkWrap-compressed images may require the original application.
Security & safety
RISK: LOWDisk image file; mounting it on a classic Mac OS emulator will give access to whatever files it contains - the files inside could be software of any safety level. Do not run executables from unknown .image archives without scanning.
Format details
in a nutshell- Generic raster/photo image file - Some systems or apps may save images with the .image extension; context determines the actual format.
Programs that open IMAGE files
Windows1 app
BasiliskII (Windows port)
Open-source Run classic Mac OS in emulation; use ShrinkWrap inside the emulated environment to access .image files. 
macOS3 apps
Apple Disk Utility
Built-in Double-click the .image file; works for DiskCopy 4.2 / NDIF images. Native ShrinkWrap format may not open - try Disk Copy (classic Mac OS) via emulator.
ShrinkWrap 3.5 (historical, via emulator)
Free Run under BasiliskII or SheepShaver classic Mac OS emulator. Mount the .image file within the emulated environment.
Basilisk II (emulator)
Open-source Configure Basilisk II with a classic Mac OS ROM and system; use ShrinkWrap inside the emulator to mount .image files. Technical details
deep spec| Format type | Proprietary classic Mac OS disk image container |
| Byte order | Big-endian (classic Mac OS convention) |
| Compression | Optional StuffIt compression (Aladdin proprietary) |
| Encryption | Optional 40-bit encryption (Aladdin proprietary) |
| Supported internal formats | ShrinkWrap native, DiskCopy 4.2, NDIF (DiskCopy 6) |
| Filesystem content | Mac HFS or HFS+ volume data (sector-by-sector copy) |
| Typical size | 400 KB - 650 MB (floppy to CD-ROM sized images) |
| Magic bytes | No publicly documented signature for native ShrinkWrap format; NDIF variant starts with 0x45 0x52 (ER...) |
| Associated OS | Classic Mac OS (System 7 - Mac OS 9) |
| Developer | Aladdin Systems, Inc. |
| MIME type | application/octet-stream |
| Successor format | Apple UDIF .dmg (Mac OS X, 2001) |
| Access today | Requires classic Mac OS emulator (e.g., Basilisk II) for native ShrinkWrap images |
| Released | 1994 (ShrinkWrap 1.x for classic Mac OS) |
| Latest version | ShrinkWrap 3.5 (1999) - last release before Aladdin's disk image tools discontinued |
IMAGE conversions
Community Q&A
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