Garmin .img

The Garmin.img format is what Garmin devices use to store the maps for its GPS units. The img files contain a header and many subfiles. Img's filestore is based on FAT system.^[1] Some old GPS units are not able to work with multiple img files so they need to be merged into one file called gmapsupp.img using programs like Mapsource.^[2]

The IMG file contains the needed information for rendering a map on a Garmin GPS unit, and may support autorouting information for those GPS units that offer navigation (i.e in-car GPS routers and some types of devices intended for hikers).^[2]

The .img file is basically a hard-disk image (complete with partition table) containing a filesystem which itself contains subfiles that provide the functionality for the Garmin GPS unit. The filesystem seems to be 'flat': that is, it doesn't directly support the concept of subdirectories, however the .GMP subfiles do provide a kind-of subdirectory structure.^[2]

Programs that read.img format

• Mapsource: www8.garmin.com/support/download_details.jsp?id=209
• GPSMapEdit: www.geopainting.com/en/

Programs that write.img format

• CGSPMapper: www.cgpsmapper.com
• Mapwel: www.mapwel.eu

Open Source Tools for .img Format

Garmin IMG Format This program is designed to aid in the decoding of Garmin IMG files. It hexdumps the IMG file side-by-side with plain-text descriptions of what the particular bytes in the file represent.^[3]

References