
Thus, although making the RGN file is simple as ABC, but somebody without using Hexeditor knowledge will

Dun worry............
Mr.TurboCCC has create a program name "SymbolExtractor_V120",
you just need to use this program open the "Gupdate.gcd" file, then Save as XXX.RGN file.
then, you have a Clean firmware "RGN" format file. Just easy as 123, right ?
No need to learn what "BD0200FF", unp2, merge.......

This program main purpose to extract all the PNG format picture files from "Gupdate.GCD"
Gupdate.gcd is firmware update files, All the PNG pictures are embedded into the firmware like your nuvi's interface picture, Map POI icon....etc,. the SymbolExtractor program can let you extract all the picture and you can view it from your computer.
beside of this, you may also replace the symbol as what you want, for example, if you don't like garmin default POI icon like shopping bag icon, just create you own and use this program to replace it.
http://turboccc.wikispaces.com/SymbolExtractor
New version v1.20 changelog:
- Added symbol replacement function. You can replace only if the size (in bytes) of the new symbol is smaller than the original. It may be a different dimension, but I have not tried it yet. Let me know if you do.
- Added RGN file save even if your source is a GCD file. Not possible to save as a GCD file for now. Once
done, put your gps in pre-boot mode and use update.exe (not supplied) to program the new firmware.
- You can use this program to convert the firmware from GCD to RGN. It has been tested with many firmware.
*** USE AT YOUR OWN RISK!!! ***