HD Photo / JPEG XR
JPEG XR was "HD Photo" and before that "Windows Media Photo".
It is now standardised as ISO/IEC 29199-2.
Here it is simply called HD Photo, because of when I wrote most of this.
There is both an overlap and a separation between DNG and HD Photo.
HD Photo competes with raw (including DNG) for some purposes. Future threads that debate "raw versus HD Photo" won't come to exactly the same conclusions as current "raw versus JPEG" threads, because HD Photo 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, and that may be HD Photo.
DNG and HD Photo can co-exist, both of them superior for various purposes to their respective alternatives.
Raw versus HD Photo in-camera
We all shoot raw!
What matters is where the raw conversion is performed. Is it in-camera, or later?
The questions are:
- how much space do either of these take on the memory card; and
- how much opportunity is there to do a better raw conversion later?
HD Photo appears to be much better technically than JPEG in-camera. Some people who shoot raw because the alternative is JPEG may choose HD Photo instead, given the choice. But HD Photo isn't as good in-camera for those who want to exploit raw image data later.
(If raw is chosen in-camera instead of HD Photo, then a further decision is whether DNG should be the raw file format. These pages make the case for using DNG in-camera).
Potential DNG exploitation of HD Photo
Use of HD Photo compression
The HD Photo compression technique may be useful for the image data in a DNG file. There are hints that Adobe would like to use this to make DNG files smaller.
Use of HD Photo for previews
My analysis suggests that an HD Photo preview could be about half of the size of a JPEG preview. This could be a useful option.
Commonality between DNG and HD Photo
XMP and Exif
Both DNG and HD Photo use XMP and Exif metadata. This suggests they could comfortably co-exist as part of a DAM workflow.