For some reason JVC went about it a little bit backwards compared to how most other head units work with custom backgrounds. Instead of doing a simple upload to the unit you have to do the following:

1. Select desired image on your computer and crop it to proper aspect ratio or as close to it as you can get. The KD-AVX77 has a 800x240 display.

2. Upload image to a flash drive or burn it to a DVD-R

3. Connect flash drive to the adapter cable (or if you don't have the adapter cable, that is when you could use the DVD, instead.)

4. Play image/DVD so that the desired image is displayed on the screen and then press pause

5. Press the "Quick Menu" button

6. Press the "User Capture" button on the lower left portion of the quick menu. The icon has a camera and a representation of the head unit together.

7. Press "Back" menu button to select either normal or zoom image mode

8. Press desired image preset number; you can select 1-4 as it can only store up to 4 images.

Once you have stored more than one image, you can switch between them by using the main A/V Settings menu.

You don't necessarily have to crop the images that you want to use as a wallpaper, but they won't display very well if they aren't fairly close to the native aspect ratio of the unit.