Can anyone tell me if it's possible to take the picture below, which I have as a pdf file and somehow convert that so I can put it into my Garmin gps?
Find the image location in Google Earth or Google Maps and create the same route using the map tools, then save as *.kml file and import into Basecamp.
What GPS are you working with? Not all of them easily accept custom maps, and some older ones don't easily accept gpx route and track info. And you specifically asked for a a gpx file, which just has track and route information. GPX files don't have maps or images.
YES, it's possible, and it doesn't involve maps or Routes, it only involves GPS Tracks. I do it all the time, but it's not a simple process. 1) Convert each PDF into a JPEG or PNG, as you did to post that image above. 2) In Google Earth, use the Image Overlay tool (in the Add menu) to import the image as an overlay. 3) Adjust the image transparency so you can see both the overlay image and the underlying Google Earth imagery. 4) Move and scale the image so it perfectly lines up with the same geographic area in Google Earth. 5) Use the Google Earth "Add Path" tool to draw a line on top of the red line from your image. 6) In Google Earth, save that path you just drew (or set of paths) as a KML file (unless you can import KML directly). 7) Use GPS Babel to convert the KML file to a GPX file. 8) Open the GPX file in MapSource or BaseCamp to adjust track colors, then load into your GPS. p.s. The track in your image above is where the 2012 NORRA Mexican 1000 Rally was going to go, but I moved the race course to a new set of roads further North-East to avoid racing through the streets of Todos Santos.