GPX or CSV file can be converted to the proprietary Garmin format GPI format (Garmin Points of Interest) format using the Garmin POI loader v2.54
OR use the one bundled with the Garmin Map Source v6.15.11
at the time of posting if there is also a BMP file of the same filename then this will be added to the Waypoints Symbol.
If you put all your POI that you want to be added to the Garmin POI then place all them in the same folder prior to starting the POI Loader and they will be placed into sub-menus otherwise it will select the single file entries only.
However the Garmin Mapsource can't open this GPI format it is specifically for the SATNAV Device only open GDB, MPS, GPX and LOC files can be opened as standard. There are two ways that I know of that will convert this GPI back into CSV or the POI format if required you might like to open the POI content in the Map Source program.
First this can be done using GPI2GPS
it does however cost 15 EUROs or its older brother GPSConvertor
for an extra 20 EUROs will convert to all formats for all makes of device including Tom-Tom, Garmin and many others.
Secondly you can convert POI file in CSV format directly to GPX (exchange format) using the excellent GPXtoPOI Convertor v1.1.8
then import directly into the Map Source if you also want to use BMP that has been downloaded in Map Source you can replace the 8 default custom waypoint symbols located on your computer with your own or from the Tescos.ZIP
file in this example that contains the CSV and BMP.
You can open these symbols with a graphic editor and use them as templates for creating your own symbols.You can add up to 64 custom waypoint symbols. These symbols must be in .bmp format and must be named numerically from "000.bmp" to "063.bmp." Custom waypoint symbols can be 16 x 16 pixels (small) or 24 x 24 pixels (large) and up to 32-bit color
Also check out my other POI tip HERE
for help on how to create your own BMP's for use with your Garmin using Adobe Photoshop
It will also convert any GPX format into CSV format for use with the POI loader using the other button on the menu maybe this program would be best called GPXtoCSV instead to avoid confusion
And this one I saved for last If you want to transfer images from the Garmin use xImage
and have your Garmi SATNAV connected.
For a full list of all POI sources then visit the Gamin POI Source
another great website full of loads of useful tools is www.freegeographytools.com
If you are unable to use xImage it means that you unit is not compatible for example the Nuvi 250 will not be found and you may see this window