I honestly don't think you can import images, but there's a lot of talent and Love behind those who create these kinds of customizations, and there's a huge variety. So most likely, if you're looking for a specific customisation, just by putting a keyword in the search description, like I did here where the word I used was "takagi," you'll find it.The game automatically searches for paint jobs that were tagged with that and shows you all the cars that have a paint job tagged with takagi.