What is IMG?

IMG files are raw disk images containing an exact byte-for-byte copy of a storage device - hard drive, floppy disk, USB flash drive, or SD card. Unlike ISO (optical media only), IMG can represent any storage medium with all partitions, boot sectors, file systems, and data intact. IMG files are uncompressed and typically match the exact size of the original disk. Used for forensic analysis, disk cloning, and bootable media creation.

IMG is used by Raspberry Pi Foundation for distributing operating system images (Raspbian/Raspberry Pi OS), by system administrators for disk cloning and backups, in digital forensics for evidence preservation, and for creating bootable USB installers. Written to drives using tools like dd (Linux), Win32 Disk Imager, Etcher, or Rufus. Essential format for embedded systems and single-board computers.

Did you know? Every Raspberry Pi OS download is an IMG file ready to write to SD cards!

History

Raw disk imaging emerged in the 1980s for forensics and backup purposes, becoming a standard format for bootable media and embedded system distribution.

Key Milestones

  • 1980s: Floppy disk imaging begins
  • 1990s: Forensic use expands
  • 2000s: Hard drive cloning tools
  • 2012: Raspberry Pi popularizes IMG
  • 2015: Etcher simplifies flashing
  • Present: Embedded system standard

Key Features

Core Capabilities

  • Raw Format: Sector-by-sector copy
  • Complete Clone: All partitions included
  • Bootable: Preserves boot sectors
  • Forensic Quality: Exact bit-level copy
  • Universal: Any storage medium
  • Uncompressed: Direct disk representation

Common Use Cases

Raspberry Pi

OS image distribution

Disk Cloning

Drive duplication

Forensics

Evidence preservation

Bootable USB

OS installer creation

Advantages

  • Exact disk replication
  • Bootable media support
  • Forensically sound
  • Simple raw format
  • Universal compatibility
  • Preserves all partitions
  • Perfect for embedded systems

Disadvantages

  • Very large file sizes
  • No compression
  • Includes empty space
  • Slow to transfer
  • Requires entire disk space
  • Not mountable on all systems

Technical Information

Format Specifications

Specification Details
File Extension .img, .raw
MIME Type application/octet-stream
Structure Raw byte stream
Compression None (can be gzipped)
File Size Equal to disk size
Bootable Yes

Common Tools

  • Writing: Etcher, Rufus, Win32 Disk Imager
  • Linux: dd, ddrescue, dcfldd
  • Mounting: Loop device (Linux), OSFMount (Windows)
  • Forensics: FTK Imager, dd, Autopsy