My wife sent me some pics through her iPhone 4S. When I received the pics on my iPad 2, they were all PNG files. When she normally sends me pictures they are in JPEG format. I can still open the files with no problem. Upon investigation, my wife said the only thing she did different was "zoom in” when taking the pics. I thought it was my iPad that was converting the files but, I guess, her phone converts them to PNG when zooming. Perhaps this is the wrong forum to ask, but am I correct?