# JPEG XR

Filename extension .jxr,[1] .hdp,[2] .wdp[2] image/vnd.ms-photo Microsoft, ITU-T, ISO/IEC 14 April 2009 12/2009 (ITU-T); 2010 edition (ISO/IEC) / 30 September 2010; 2 years ago Graphics file format TIFF ITU-T Rec. T.832 (12/2009), ISO/IEC 29199-2:2010 Yes ITU-T T.832 (12/2009), ISO/IEC 29199-2: 2010

JPEG XR[3] (abbr. for JPEG extended range[4]) is a still-image compression standard and file format for continuous tone photographic images, based on technology originally developed and patented by Microsoft under the name HD Photo (formerly Windows Media Photo). It supports both lossy and lossless compression, and is the preferred image format for Ecma-388 Open XML Paper Specification documents.

Support for the format is available in Adobe Flash Player 11.0, Adobe AIR 3.0, Sumatra PDF 2.1, Windows Imaging Component, .NET Framework 3.0, Windows Vista, Windows 7, Windows 8, Internet Explorer 9, Internet Explorer 10.[citation needed]

## History

Microsoft first announced Windows Media Photo at WinHEC 2006,[5] and then renamed it to HD Photo in November of that year. In July 2007, the Joint Photographic Experts Group and Microsoft announced HD Photo to be under consideration to become a JPEG standard known as JPEG XR.[6][7] On 16 March 2009, JPEG XR was given final approval as ITU-T Recommendation T.832 and starting in April 2009, it became available from the ITU-T in "pre-published" form.[1] On 19 June 2009, it passed an ISO/IEC Final Draft International Standard (FDIS) ballot, resulting in final approval as International Standard ISO/IEC 29199-2.[8][9] The ITU-T updated its publication with a corrigendum approved in December 2009,[1] and ISO/IEC issued a new edition with similar corrections on 30 September 2010.[10]

In 2010, after completion of the image coding specification, the ITU-T and ISO/IEC also published a motion format specification (ITU-T T.833 | ISO/IEC 29199-3), a conformance test set (ITU-T T.834 | ISO/IEC 29199-4), and reference software (ITU-T T.835 | ISO/IEC 29199-5) for JPEG XR. In 2011, they published a technical report describing the workflow architecture for the use of JPEG XR images in applications (ITU-T T.Sup2 | ISO/IEC TR 29199-1).

## Description

### Capabilities

JPEG XR is an image file format that offers several key improvements over JPEG, including:[11]

Better compression
JPEG XR file format supports higher compression ratios in comparison to JPEG for encoding an image with equivalent quality.
Lossless compression
JPEG XR also supports lossless compression. The signal processing steps in JPEG XR are the same for both lossless and lossy coding. This makes the lossless mode simple to support and enables the "trimming" of some bits from a lossless compressed image to produce a lossy compressed image.
Tile structure support
A JPEG XR coded image can be segmented into tile regions. The data for each region can be decoded separately. This enables rapid access to parts of an image without needing to decode the entire image. When a type of tiling referred to as "soft tiling" is used, the tile region structuring can be changed without fully decoding the image and without introducing additional distortion.
Support for more color accuracy
In image and graphics representations, the color associated with each point in the picture (called a pixel) is represented as a set of numbers. Each color can be expressed as a combination of numbers that each represent the intensity of one of the components of a color (known as the channel) which consists of Red, Green and Blue (the three colors of light) color primary. Such a color scheme is called the RGB color model. Using an alternative set of color primaries, graphic files may treat the color of each point as a combination of Cyan, Magenta, Yellow, and Black (the four ink colors of printers) and therefore store the color of each point in four channels. Such a color scheme is called the CMYK color model. When the image being stored contains only black, white and shades of gray as colors, the image may be represented using a single grayscale channel for each pixel that only represents the intensity of the gray shade.
JPEG supports 24-Bit RGB (also known as truecolor): This representation stores each channel as an 8-bit number, an integer number from 0 to 255. In this case, the greater the number, the more intense the color component is. For instance, 25 in red channel represents dark red while 255 indicates fully vibrant red. This enables more than 16 million color possibilities. JPEG also supports 8-bit grayscale scheme, so that each pixel can have one of 256 possible shades of gray.
Also supported is 15-Bit and 16-Bit RGB (also known as Highcolor), along with 30-Bit RGB.[citation needed]
JPEG XR adds supports for 48-bit integer RGB (also known as deep color): This representation stores the values of each of the three channels as a 16-bit number, an integer number from 0 to 65,535, where 0 denotes least intensity and 65535 the greatest. Therefore, each channel stores a much finer grade of intensity.
JPEG XR also supports 16-bit per component (64-bit per pixel) integer CMYK color model.[12]
16-bit and 32-bit fixed point color component codings are also supported in JPEG XR. In such encodings, the most-significant 4 bits of each color channel are treated as providing additional "headroom" and "toe room" beyond the range of values that represents the nominal black-to-white signal range.
Moreover, 16-bit and 32-bit floating point color component codings are also supported in JPEG XR. In these cases the image is interpreted as floating point data, although the JPEG XR encoding and decoding steps are all performed using only integer operations (to simplify the compression processing).
The shared-exponent floating point color format known as RGBE (Radiance) is also supported, enabling more faithful storage of High Dynamic Range (HDR) images.
In addition to RGB and CMYK formats, JPEG XR also supports grayscale and multi-channel color encodings with an arbitrary number of channels.
The color representations, in most cases, are transformed to an internal color representation. The transformation is entirely reversible, so that this color transformation step does not introduce distortion and lossless coding modes can be supported.
Transparency map support
An alpha channel may be present to represent transparency, so that alpha blending overlay capability is enabled.
Compressed-domain image modification
In JPEG XR, full decoding of the image is unnecessary for converting an image from a lossless to lossy encoding, reducing the fidelity of a lossy encoding, or reducing the encoded image resolution.
Full decoding is also unnecessary for certain editing operations such as cropping, horizontal or vertical flips, or cardinal rotations.
The tile structure for access to image regions can also be changed without full decoding and without introducing distortion.
A JPEG XR image file may optionally contain an embedded ICC color profile, to achieve consistent color representation across multiple devices.
Exif and XMP metadata formats are also supported.

### Container format

One file container format that can be used to store JPEG XR image data is specified in Annex A of the JPEG XR standard. It is a TIFF-like format using a table of Image File Directory (IFD) tags. A JPEG XR file contains image data, optional alpha channel data, metadata, optional XMP metadata stored as RDF/XML, and optional Exif metadata, in IFD tags. The image data is a contiguous self-contained chunk of data. The optional alpha channel, if present, can be compressed as a separate image record, enabling decoding of the image data independently of transparency data in applications which do not support transparency. (Alternatively, JPEG XR also supports an "interleaved" alpha channel format in which the alpha channel data is encoded together with the other image data in a single compressed codestream.)

Being TIFF-based, this format inherits all of the limitations of the TIFF format including the 4 GB file-size limit.

New work has been started in the JPEG committee to enable the use of JPEG XR image coding within the JPX file storage format — enabling use of the JPIP protocol, which allows interactive browsing of networked images.[8] Additionally, a Motion JPEG XR specification was approved as an ISO standard for motion (video) compression in March 2010.[13]

### Compression algorithm

Comparison between JPEG 2000, JPEG XR, and JPEG.

JPEG XR's design[1][14] is conceptually very similar to JPEG: the source image is optionally converted to a luma-chroma colorspace, the chroma planes are optionally subsampled, each plane is divided into fixed-size blocks, the blocks are transformed into the frequency domain, and the frequency coefficients are quantized and entropy coded. Major differences include the following:

• JPEG supports bit depths of 8 and 12 bits; JPEG XR supports bit depths of up to 32 bits. JPEG XR also supports lossless and lossy compression of floating-point image data (by representing the floating-point values in an IEEE 754-like format, and encoding them as though they were integers) and RGBE imagery.
• JFIF and other typical image encoding practices specify a linear transformation from RGB to YCbCr, which is slightly lossy in practice because of roundoff error. JPEG XR specifies a lossless colorspace transformation, given (for RGB) by
$V = B - R\,$
$U = G - R - \left\lceil \frac{V}{2} \right\rceil$
$Y = G - \left\lceil \frac{U}{2} \right\rceil$
• While JPEG uses 8 × 8 blocks for its frequency transformation, JPEG XR primarily uses 4 × 4 block transforms. (2 × 4 and 2 × 2 transformations are also defined for special cases involving chroma subsampling.)
• While JPEG uses a single transformation stage, JPEG XR applies its 4 × 4 core transform in a two-level hierarchical fashion within 16 × 16 macroblock regions. This gives the transform a wavelet-like multi-resolution hierarchy and improves its compression capability.
• The DCT, the frequency transformation used by JPEG, is slightly lossy because of roundoff error. JPEG XR uses a type of integer transform employing a lifting scheme, which resembles a 4 × 4 DCT but is lossless (exactly invertible).
• JPEG XR allows an optional overlap prefiltering step before each of its 4 × 4 core transform stages. The filter operates on 4 × 4 blocks which are offset by 2 samples in each direction from the 4 × 4 core transform blocks. Its purpose is to improve compression capability and reduce block-boundary artifacts at low bitrates. At high bitrates, where such artifacts are typically not a problem, the prefiltering can be omitted to reduce encoding and decoding time. The overlap filtering is constructed using integer operations following a lifting scheme, so that it is also lossless.
• In JPEG, the image DC coefficients of the DCT are predicted by applying DC prediction from the left neighbor transform block, and no other coeffients are predicted. In JPEG XR, blocks are grouped into macroblocks of 16 × 16 samples, and the DC coefficients from each macroblock are passed through another level of frequency transformation, leaving three types of coefficients to be entropy coded: the macroblock DC coefficients (called DC), macroblock-level AC coefficients (called "lowpass"), and lower-level AC coefficients (called AC). Prediction of coefficient values across transform blocks is applied to the DC coefficients and to an additional row or column of AC coefficients as well.
• JPEG XR supports the encoding of an image by decomposing it into smaller individual rectangular tile area regions. Each tile area can be decoded independently from the other areas of the picture. This allows fast access to spatial areas of pictures without decoding the entire picture.
• JPEG XR's entropy coding phase is more adaptive and complex than JPEG's, involving a DC and AC coefficient prediction scheme, adaptive coefficient reordering (in contrast to JPEG's fixed zigzag ordering), and a form of adaptive Huffman coding for the coefficients themselves.
• JPEG uses a single quantization step size per DC/AC component per color plane per image. JPEG XR allows a selection of DC quantization step sizes on a tile region basis, and allows lowpass and AC quantization step sizes to vary from macroblock to macroblock.
• Because all encoding phases except quantization are lossless, JPEG XR is lossless when all quantization coefficients are equal to 1. This is not true of JPEG. JPEG defines a separate lossless mode which does not use the DCT, but it is not implemented by libjpeg and therefore not widely supported.

The HD Photo bitstream specification claims that "HD Photo offers image quality comparable to JPEG-2000 with computational and memory performance more closely comparable to JPEG", that it "delivers a lossy compressed image of better perceptive quality than JPEG at less than half the file size", and that "lossless compressed images … are typically 2.5 times smaller than the original uncompressed data".

## Software support

A reference software implementation of JPEG XR has been published as ITU-T Recommendation T.835 and ISO/IEC International Standard 29199-5.

The following notable software products natively support JPEG XR:

Product Name Publisher Read support Write support
Corel Paint Shop Pro Corel Yes Yes [15]
Fast Picture Viewer Axel Rietschin Software Developments Yes N/A [16]
ImageMagick ImageMagick Studio LLC Yes Yes [17]
Internet Explorer 9 Microsoft Yes N/A [18][19]
Microsoft Expression Design Microsoft Yes Yes [20]
Microsoft Expression Media Microsoft Yes No
Microsoft Image Composite Editor Microsoft Yes Yes [21]
PhotoLine Computerinsel Yes Yes
Windows Live Photo Gallery Microsoft Yes Yes
Windows Photo Gallery Microsoft Yes Yes
Windows Photo Viewer Microsoft Yes N/A
XnView Pierre-Emmanuel Gougelet Yes Yes [22][23]
Xara Designer Pro Xara Group Limited Yes No [24]
Zoner Photo Studio Zoner Software Yes Yes

The following notable software support JPEG XR through a Plug-in:

Product name Publisher Plug-in name Plug-in publisher Read support Write support
Adobe Photoshop (CS2,CS5-CS6) Adobe Systems JPEG XR File Format Plug-in for Photoshop Microsoft Corporation Yes Yes [25][26]
GIMP The GIMP Development Team JPEG XR plugin for GIMP C. Hausner Yes Yes [27]
IrfanView 4.25 Irfan Skiljan HDP version 4.26 Irfan Skiljan Yes No [28]
Paint.NET Rick Brewster JPEG XR plugin for Paint.NET C. Hausner Yes Yes [29]
Quick Look Apple Inc. JPEG XR plugin for Quick Look B. Hoary Yes N/A [30]

The following APIs and software frameworks support JPEG XR and may be used in other software to provide JPEG XR support to end users:

Product Name Publisher Read support Write support
Integrated Performance Primitives (IPP) Intel Yes Yes [32][33]
PICTools Accusoft Pegasus Yes Yes [35][36][37]
Windows Imaging Component (WIC) Microsoft Yes Yes

The 2011 video game, Rage, employs JPEG XR compression to compress its textures.[38]

## Licensing

Microsoft has patents on the technology in JPEG XR. A Microsoft representative stated in a January 2007 interview that in order to encourage the adoption and use of HD Photo, the specification is made available under the Microsoft Open Specification Promise, which asserts that Microsoft allows implementation of the specification for free, and will not file suits on the patented technology for its implementation,[39] as reportedly stated by Josh Weisberg, director of Microsoft's Rich Media Group. As of 15 August 2010, Microsoft made the resulting JPEG XR standard available under its Community Promise.[40]

In July 2010, reference software to implement the JPEG XR standard was published as ITU-T Recommendation T.835 and International Standard ISO/IEC 29199-5. Microsoft included these publications in the list of specifications covered by its Community Promise.[40]

In April 2013, Microsoft released an open source JPEG XR library under the BSD licence.[41] This resolved any licencing issues with the library being implemented in software packages distributed under popular open source licences such as the GNU General Public License, with which the previously released "HD Photo Device Porting Kit"[42] was incompatible with.

## References

1. ^ a b c d "Recommendation T.832 (03/2009, updated 12/2009): Information technology - JPEG XR image coding system - Part 2: Image coding specification". International Telecommunication Union - Standardization sector (ITU-T). December 2009. Retrieved 18 December 2009.
2. ^ a b "Microsoft Device Porting Kit Specification". Microsoft Corporation. 7 November 2006. Retrieved 8 November 2009.
3. ^ Bill, Crow (1 November 2006). "Introducing". Microsoft Developer Network blogs, Bill Crow's blog. Microsoft Corporation. Retrieved 24 October 2009.
4. ^ Bill, Crow (31 July 2007). "Industry Standardization for HD Photo". Microsoft Developer Network blogs, Bill Crow's blog. Microsoft Corporation. Retrieved 14 August 2011.
5. ^ Microsoft shows off JPEG rival
6. ^ "Microsoft’s HD Photo Technology Is Considered for Standardization by JPEG". Microsoft Corporation. 31 July 2007. Retrieved 31 July 2007.
7. ^ "JPEG 2000 Digital Cinema Successes and Proposed Standardization of JPEG XR". Join Photographic Experts Group. 6 July 2007. Retrieved 31 July 2009.
8. ^ a b Sharpe, Louis (17 July 2009). "Press Release – 49th WG1 Sardinia Meeting". Joint Photographic Experts Group. Retrieved 24 October 2009.
9. ^ "ISO/IEC 29199-2:2009 Information technology - JPEG XR image coding system - Part 2: Image coding specification". International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC). 14 August 2009. Retrieved 18 December 2009.
10. ^ "ISO/IEC 29199-2:2010 Information technology - JPEG XR image coding system - Part 2: Image coding specification". International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC). 30 September 2010. Retrieved 18 December 2010.
11. ^ Bill, Crow (30 July 2009). "JPEG XR is Now an International Standard". Microsoft Developer Network blogs, Bill Crow's blog. Microsoft Corporation. Retrieved 24 October 2009.
12. ^ Crow, Bill (1 June 2006). "Pixel Formats (Part 1: Unsigned Integers)". Bill Crow's Digital Imaging & Photography Blog. Microsoft Developer Network. Retrieved 26 October 2009.
13. ^ "JPEG launches Innovations group, new book " JPEG 2000 Suite " published". jpeg.org. 19 March 2010.
14. ^ S. Srinivasan, C. Tu, S. L. Regunathan, and G. J. Sullivan, “HD Photo: A New Image Coding Technology for Digital Photography”, SPIE Applications of Digital Image Processing XXX, SPIE Proceedings, volume 6696, paper 66960A, September 2007.
15. ^ "Corel Paint Shop Pro® Photo X2 Introduces Integrated Support for the Microsoft HD Photo Format". 20 November 2007. Retrieved 14 July 2011.
16. ^
17. ^ "ImageMagick Image Formatssite". ImageMagick Studio LLC. Retrieved 6 May 2013.
18. ^ "Image Support". Microsoft Corporation. 2010. Retrieved 29 May 2010.
19. ^ Olivier, Frank (9 April 2010). "Benefits of GPU-powered HTML5". Microsoft Corporation. Retrieved 29 May 2010.
20. ^ Crow, Bill (27 March 2007). "Expression Design Includes HD Photo Support". Microsoft Corporation. Retrieved 1 June 2010.
21. ^ "Microsoft Research Image Composite Editor". Microsoft Research. Retrieved 9 March 2011.
22. ^ Gougelet, Pierre E. "Formats". Retrieved 10 September 2010.
23. ^ Gougelet, Pierre E. "Added/Changed Features to XnView". Retrieved 11 May 2011.
24. ^ "Advanced Features: HD Photo import". Xara Group. Retrieved 10 September 2010.
25. ^ "HD Photo Plug-ins for Photoshop are Released". Bill Crow's Digital Imaging & Photography Blog. MSDN Blogs. 6 December 2007. Retrieved 6 December 2007.
26. ^ "JPEG XR File Format Plug-in for Photoshop". Microsoft Research. 30 January 2013. Retrieved 14 April 2013.
27. ^ JPEG XR plugin for GIMP
28. ^ http://www.irfanview.com/plugins.htm
29. ^ JPEG XR plugin for Paint.NET
30. ^ JPEG XR plugin for Quick Look
31. ^ a b "Flash Player 11 and AIR 3 Release Notes for Adobe Labs". 12 July 2011. Retrieved 14 July 2011.
32. ^
33. ^
34. ^ "LEADTOOLS JPEG-XR Image Compression SDK". LEADTOOLS. Retrieved 29 July 2011.
35. ^ "Accusoft Pegasus PICTools Photo Compression & File Formats". Accusoft Pegasus. Retrieved 29 July 2011.
36. ^ Brooks, Steve (2 December 2010). "Apply Compression to RAW Images without Sacrificing Quality: Introduction to JPEG XR". The Code Project. Retrieved 1 October 2011.
37. ^ "HD Photo Now Available Within Pictools SDK by Pegasus Imaging". Start64!. Tampa, FL. 1 October 2007. Retrieved 1 October 2011.
38. ^ Carmack, John (29 October 2010). "John Carmack discusses RAGE on iPhone/iPad/iPod". Bethesda Blog. ZeniMax Media Inc. Retrieved 8 March 2011.
39. ^ Stephen Shankland (23 January 2007). "Vista to give HD Photo format more exposure". CNet. Retrieved 9 March 2007.
40. ^ a b "Microsoft Community Promise". Retrieved 16 July 2011.
41. ^ "jxrlib JPEG-XR library". Microsoft. 1 April 2013. Retrieved 16 April2013.
42. ^ "HD Photo Device Porting Kit 1.0". Microsoft. 21 December 2006. Retrieved 9 August 2007.