Introduction to JPEG XR (was HD Photo)


DNG versus HD Photo / JPEG XR


I have no commercial relationship with Microsoft, other than being a user of some of their products.


If you know of errors here, please let me know, with suitable supporting material, and I'll correct them.

JPEG XR was "HD Photo" and before that "Windows Media Photo".
It is now standardised as ISO/IEC 29199-2.
Most of these pages were written before it became a standard.


What is HD Photo?

HD Photo is an image file format, launched by Microsoft during 2006, specifically for digital photography. It has several innovative features, and lots of patents held by Microsoft.

From Pegasus Imaging:
"HD Photo (formerly Windows Media Photo) is a new format for end-to-end digital photography which offers higher image quality, greater preservation of data and advanced features for today’s digital imaging applications. It is a still image compression algorithm for continuous tone photographic images and features lossy, as well as lossless, compression, multiple colorspaces, a wide dynamic range, and extensive metadata support".

HD Photo is technically a good (and sometimes superior) alternative to many uses of TIFF, JPEG, JPEG2000, and perhaps PNG (continuous tone) too. That doesn't mean it will replace all use of TIFF and JPEG in the near future. Think of what would have to happen for the world to switch over from JPEG to HD Photo! JPEG will still be popular on the web in decades to come.

Here is a useful (and I believe pretty accurate) summary of HD Photo, listing differences between JPEG and HD Photo:


JPEG (Joint Photographic Experts Group) is a working group of the International Organisation for Standardization / International Electrotechnical Commission, and of the International Telecommunication Union.

It is responsible for the JPEG, and more recently the JPEG 2000, family of imaging standards.

What is JPEG XR?

"JPEG XR" ("Extended Range") is simply the name chosen for HD Photo to become standardised by JPEG.

  • In 23-27 April 2007, JPEG held their 41st meeting in San Jose California, where Microsoft introduced their HD Photo proposals, and provided a range of software and picture samples.
  • In 02-06 July 2007, JPEG held their 42nd meeting in Lausanne, Switzerland, where a resolution was adopted to progress with the JPEG XR work item. This needs a formal ballot by JPEG national delegations for approval. The ballot deadline for this new project is early October 2007.
  • JPEG XR is now an ISO standard, ISO/IEC 29199-2; and an ITU-T Recommendation, T.832.
Further reading:

Openness and licensing

This is probably the single most contentious aspect of HD Photo / JPEG XR. Many people are very suspicious about Microsoft's motives and whether their future actions will screw up photographers. This is not helped by the fact that Microsoft's position has changed significantly since the initial launch of Windows Media Photo, and also there have been some mis-quotes in the press. A flavour of the suspicion can be seen in this Slashdot thread:

It is clear from Bill Crow's podcasts (below) that Microsoft intend to establish HD Photo as a generally available photograph file format. But they do not intend to provide royalty-free support for its compression techniques independently of the use of HD Photo to support photographs. Therefore, any royalty-free licensing will be conditional on the use of the documentation and Device Porting Kit specifically for support of HD Photo itself. And presumably Microsoft will exercise its patent rights where patents are used for purposes other than their intention. (But those podcasts pre-dated JPEG's announcements, so perhaps things will change again?)

All of us use many patented products every day, mostly without discomfort. What matters is whether those patents are handled in a way that is convenient for us, either because the patent-holder charges "reasonable" fees or commits to royalty-free use, or because our immediate suppliers have themselves handled the requirements of the patent-holders. Unisys held patents on GIF, but most users of GIF weren't impacted by that. Forgent held patents on JPEG, but most users of JPEG weren't impacted by that either. What matters is whether the main organisations and companies concerned with JPEG XR can ensure that the rest of us don't suffer from those patents.

JPEG reports: "One important aspect regarding the standardization of HD Photo is Microsoft's commitment to make its patents that are required to implement the specification available without charge".


Bill Crow

Bill Crow is Microsoft's articulate and informative evangelist for HD Photo. He maintains a Blog that is mainly about HD Photo and topics related to it. His podcasts are well worth listening to. Much of the information in these pages was influenced by his podcasts.


Podcasts

MP3 podcast with Bill Crow
This 68 minute podcast has significant discussion about this topic, and is well worth listening to for a perspective from a Microsoft insider:

Start at about minute 19 for a discussion of the basis and origins of HD Photo; about minute 52 for a discussion of how open it is intended to be.

This Week in Media: "TWiM 51: Something not JPEG" (podcast with Bill Crow)
This more rambling 113 minute podcast has a similar theme, but fills in some gaps. Segments of discussion start at or after these minutes:

14: start of talk about HD Photo; 18: Open source potential; 20: mention of raw & DNG; 25: differences compared with raw; 35: how floating point numbers are held economically (1 exponent); 37: shopping list for HD Photo; 39: JPEG2000 discussion; 45: back to HD Photo shopping list; 49: discussion about bit-exact and ability to avoid gradual degradation; 52: Photosynth; 59: low end cameras and efficient implementations; 62: Photoshop plug-in; 63: Linear RGB similar to scRGB; 65: Device Porting Kit and chip makers for cameras (SunPlus, and others); 67: No fee, no licensing fee, openness, etc; 73: Even Bill Crow will not always let go of raw; 82: Must be in-camera, because that is where the large volumes are, and intent to standardise it; 84: End of the main discussion.

Technology Today: Tim Grey of Microsoft on JPEG XR
Tim Grey is Director of the Pro Photo Community team at Microsoft. This is a question and answer session with Megan Cunningham.

O'Reilly Digital Media: Tim Grey on HD Photo and Microsoft Technology
Tim Grey's interview with Derrick Story on the expo floor at Photoshop World 07 in Las Vegas.


Turf wars

Contrary to some articles, HD Photo is not directly fighting a turf war with DNG. But it is fighting a turf war with raw shooting generally, and more. Here are three main turf wars that will probably be played out over the next few years. (Mention of "DNG" by those articles is a distraction here, because it isn't "singled out" in the turf war between JPEG XR and raw).

Competing with "raw" generally

This will be an extension of the existing "competition" between JPEG and raw. A difference will be that future threads that debate "raw versus JPEG XR" won't come to exactly the same conclusions as current "raw versus JPEG" threads, because JPEG XR is capable of lots more than JPEG.

HD Photo won't eliminate the use of raw, because HD Photo needs basic raw conversion (eg. demosaicing) to be performed in-camera, and many photographers will continue to want that done later. But some photographers who use raw because the current alternative is "just" JPEG will welcome something significantly better than JPEG.

Competing with JPEG (and JPEG 2000)

We will see lots of debates about "JPEG versus JPEG XR". (In fact, we have already seen these from the launch of HD Photo, if not earlier). People will correctly point out that JPEG is needed on the web until browsers support JPEG XR, and even then browsers will continue to support JPEG.

The main initial battle will be in-camera JPEG versus JPEG XR. I suspect some cameras will offer a choice, because it will be several years before JPEG XR is supported anywhere near as widely as JPEG, by photo-editors and printing services, etc.

JPEG 2000 is becoming popular in various niches such as geospatial, cultural heritage and archival, biometric (fingerprints, facial, iris), and medical imaging. It will be hard for HD Photo to compete with that investment for years, especially where JPEG 2000 provides important features that HD Photo doesn't. Use of JPEG 2000 will probably increase in parallel with increasing popularity of HD Photo!

Competing with TIFF (TIFF 6.0)

This is an extension of the existing competition between JPEG and TIFF, but JPEG XR has far more capability than JPEG to compete with TIFF. In its lossless form, I suspect that when our photo-editors support it, many of us (not all) will have little or no trouble using JPEG XR (lossless) instead of TIFF for interchange.


Some useful links

Microsoft

Others