It depends honestly, I don't think VBA displays it as how it's stored because, for example, strings are displayed as tiles despite the physical tilemap not existing. Usually if the image is LZ77 compressed you can find it by activating Logging -> SWI, bringing up the image, going to the log and sifting through the individual LZ77 lines with offsets in something like GBA Graphics Editor. This is explained better in my Title Screen Tutorial, but it might be worth posting a thread in the Beginner's Lounge if you're still confused after.