Garmin IMG Format / News: Recent posts

The 1.0 release of the IMG Format spec document incorporates a large number of corrections and additions, including a brief section on the NOD subfile. It represents a major change from previous versions.

I've released a new version of the Img Decoder package. This includes a number of critical bug fixes that caused incorrect parsing of large IMG files as well as several enhancements for decoding RGN and the known parts of NET.

I am way behind on updating the IMG File Format document. I have several corrections and additions stacked up and hope to get that out soon.

The IMG Decoder package is a Garmin IMG decoder that breaks down the known sections of an IMG file into a hex dump with English descriptions of the corresponding data. It's very useful for those who wish to analyze the IMG file format (and will hopefully accelerate the process of working out the unknown sections).

Some new tools are available in the CVS repository.

1. A Java-based ImgViewer from Par Spjuth, uploaded with his permission. While incomplete, it does provide a nice methodology for parsing and viewing IMG files. See the README file for more information. There are no plans to make this an official package or continue development, but it will be kept in CVS for reference purposes.

2. imgdecode is designed to aid those people who are attempting to decode the IMG file format. It hexdumps an IMG file alongside text translations of the data where known. It should make it easy to identify unknown blocks of data, reference file offsets, etc. This is a work in progress and it will be packaged when it's more complete.

I've added rev 1 of a document that describes the TDB file. This one covers the v3.00 format and will eventually be expanded to include what is known about the v4.x files.

I have uploaded v0.4.2 of the IMG format specificaiton. Somehow, I have completely managed to omit references to the XOR byte (the first byte of the IMG file) in previous documents.

The IMG File Format document has been updated to include what is known about the NET subfile (which is not a whole lot, but certainly more than is known about NOD).