Format AR2 is format developed by Sony. This company has created its own file format based on RAW, which is basically the same as RAW, but it has some minor changes that are making him unique. Sony has also two another file formats that are SRF and ARW. The main advantage of this file format is its high quality, which can be used during taking pictures. But there is price for this advantage, which is enormous size of files saved in this file format. That´s why it is used only for photos and it is not used in creation of films or similar things.
One of applications that can open these files is Adobe Photoshop by Adobe Systems. It hasn´t got problems with viewing or editing files saved in this file format. Available is its paid or trial version.