This is a plugin for GIMP that allows reading and writing of JPEG XR image files. It has been tested on Windows and Ubuntu with GIMP 2.8.4.
Almost all pixel formats supported by JPEG XR can be loaded. However, non-compatible formats will first be converted to a representation that GIMP understands (this means you'll loose HDR data for example). All RGB pixel formats get converted to 24bpp RGB, all RGBA formats to 32bpp BGRA, and all grayscale formats to 8bpp Gray. Black-white images are imported as indexed images.