ah ah, thank you ! The noise (what you call "pixelized effect") is just because I I have lightened the picture a little, that was super dark at first. Easy effect. Just need to take night photos without flash !
Argh, I know this word (thanks to my english version of photoshop, I think >__>) but i don't thought to put it in this sentence... I must improve my english, meh. I know how to do it, don't worry, but I love to see picture with ^^