What i was meaning is that you can modify any BMP image file to the required picture size of 480 x 320 pixels, however it maybe has to have a native Bit Depth of 16. I get that GIR_Editor certainly doesn't allow you to do that modification, nor indeed create such a file. However ,once you have the correct size BMP it should be able deal with that image and allow you to substitute it into an existing Logo BIN file which has been opened in the program, replacing the image file/s of the same type and picture size that it originally contained.

There's an explanation by turboccc, here, [Only registered and activated users can see links. ], on how to change the splash image in a nuvi 37xx device which uses PNG files rather than BMPs in the logo BIN file, but the principle is the same so it should work provided GIR_Editor can handle working with BMP files which i'm sure it does. I guess you'll just have to download a heap of logos to try finding one compatible that uses 480 x 320 x16 BMP, look here: [Only registered and activated users can see links. ].