It's the whole file, not just a preview. Almost 2mb. So I don't think it's for preview.
Oh, you might be right, it might be the last image, that gets displayed when the camera is turned on in playback mode. Even so, it seems a waste of memory to keep the whole file in memory like that. If that's what it is, I wonder if the camera reloads it from the SD card each time the battery is removed, or if the memory can survive for a while without a battery.
Anyway, if that is indeed the jpeg that gets displayed when the camera is turned on in playback mode, it is interesting that it's at the same location in the dump, even after a photo is taken. This suggest that either this is a specially reserved memory for it, or that malloc somehow remembers that this location is in use, even after a restart (which I find unlikely).
Another question is, is this image loaded every time the camera starts in playback mode, or does it stay in the memory? When I wake up, I'll do some tests, such as corrupting the memory there and see what happens