It won't. I already did some tests (not really looking into the actual RAW file format, so I was just screwing around a bit)... I just wrote a lot of garbage (0xFFFFFFFF, whatever) somewhere within the RAW buffer every time gui_redraw() was called and I ended up with pictures with a strangely-colored line over them. So the RAW buffer is writable and the OS doesn't care what you write in there, it's only overwritten as soon as you take a picture, so it's ok for most things. If you really need something amazingly complex, you'll still have a few hundreds of kilobytes left (I think about 700 kB on my S5IS), which is a lot of memory.