Just tried on my own 1520 and it says also that it is processing image if i go straight to view photo. It seems to just work like that.
Image you see on screen before taking photo is image how cameras sensor sees it. It doesn't represent image how it will look like when you take photo especially on low light situations. On very good lighting though, photo will turn out like camera sees it. You just need to take few sample photos to find out right settings.
It is software that tries to make photos brighter on low light situations. I think general part of people prefer it like that, oh and phone reviewers too. Brighter photo better camera... well not in my opinion anyways.