Microsoft originally developed this format for High Definition Photos, HDP, in 2006 and revised in 2009. In 2009 it was released jointly by Microsoft and the Joint Photographic Experts Group, JPEG. It reached its final form in 2012. It can achieve 2X better compression than the original JPG format and has both lossless and lossy capabilities. It also is capable of better color accuracy using deep color modes and it can support Transparency (alpha plane).
From the standards web site: The JPEG XR specification enables greater effective use of compressed imagery with this broadened diversity of application requirements. JPEG XR supports a wide range of color encoding formats including monochrome, RGB, CMYK and n-component encodings using a variety of unsigned integer, fixed point, and floating-point decoded numerical representations with a variety of bit depths. The primary goal is to provide a compressed format specification appropriate for a wide range of applications while keeping the implementation requirements for encoders and decoders simple. A special focus of the design is support for emerging high dynamic range (HDR) imagery applications.
 Support for the format
Windows Imaging Component
There are no cameras currently providing photos in this JPEG XR (.JXR) format.
 Sampling depths
Support for a wide range of decoded sample formats (many of which support high dynamic range imagery):
- monochrome, RGB, CMYK, YUV, or n-component image representation,
- 8- or 16-bit unsigned integer,
- 16- or 32-bit fixed point,
- 16- or 32-bit floating point,
- several packed bit formats,
- 1-bit per sample monochrome,
- 5- or 10-bit per sample RGB, - 5 bit results in 3 colors in 16 bits (green can have 6 bits) while 10 is for 32 bit deep color.
- Radiance RGBE.
- True color is supported in 24 bits or 32 bits with alpha coding.
- 32 bit modes do not support lossless encoding.
- maximum file size is 4 GB (Tiff limit).
- The compressed file is stored in a TIFF container along with files containing Metadata which includes optional ICC Profile (for consistent color representation across multiple devices), Exif, and XMP.
- Provides better perceived quality than JPG in half the space.
- Provides 2.5 better compression than raw data in a lossless format.
- Provides image quality comparable to JPEG 2000 with computational and memory performance comparable to JPEG. Only integer operations are used internally with no division.
- use of the same signal processing operations for both lossless and lossy compression operation. Transforms are reversible.