What is a MPO file?
Developed by The Camera & Imaging Products Association (CIPA), the MPO file extension stores two images captured by an imaging device, preferably a digital camera (Fujifilm FinePix Real 3D, for example). The two pictures are in JPG format but are combined to create a 3D stereoscopic one.
The combination appears three dimensional when viewed using a supported device (say a 3D monitor or TV). The MPO extension belongs to the raster images category and can also be converted to an anaglyph image to view it using 3D glasses. If you try to view a standard JPG via these glasses, you will probably only see the left image and the right side being blank.
Nintendo 3DS is also capable of creating MPO files with a resolution of 640 x 480 pixels. An MPO file can store N number of JPGs, but it is mostly used for generating stereoscopic images.
How to Open MPO Files
How to Make MPO Files
Exact steps for creating MPO files will vary by program and operating system. Download one of the above listed programs and you should be able to follow typical procedure for opening files or creating files from the File menu. Typically you will select File > Open or File > New and continue through the prompts. Some programs may follow a different procedure for either creation or opening of files.