In Windows 7, you can view RAW pictures in Windows Explorer or Photo Viewer if you have the right codec for your specific camera installed on your PC. If you’re having problems seeing your RAW files, download and install the Microsoft Camera Codec Pack. If you’re still having problems, your camera’s format might not be supported. Check the list of supported formats provided on codec pack’s download page for more info.
RAW pictures are high-quality, uncompressed files that differ by camera manufacturer. Some common file name extensions for RAW picture files include: .cr2, .crw, .dng, .nef, .orf, .rw2, .pef, .arw, .sr2, .srf, and .tif.