In addition to the recent updates to Lightroom and Camera RAW, Adobe announced some changes to its DNG specification. The widely used Raw specification, recently updated to DNG 1.4, now offers the inclusion of lossy compression.
On The Adobe Blog, Tom Hogarty described the the update by saying "A lossy compressed DNG file is much smaller but maintains the flexibility of raw data." As you can see in the image above, it does a better job of handling dynamic range than the JPEG example, while around 1/3 of the size of the full, standard DNG. It would also allow users to maintain all the editing controls traditionally associated with Raw formats.
Talking to DPReview, Hogarty explained:
"Lossy DNG allows something in-between the two in terms of size but retains the flexibility in terms of adjusting White Balance and preserving detail. For example, the out-takes from a wedding shoot, that the photographer is unlikely to ever be able to sell or make any money from. This gives them a way of reducing the amount of storage space they need, but they still have the file if they do ever need it.
It's based on standard JPEG compression. What's lost is some of the range of the adjustments you can make - if a file is four or five stops underexposed, you'll find it's not quite as flexible as the full file. You can still do a lot, though and it's only in extreme case that you might notice."
DNG 1.4 also brings along a few other tools as well. The files will now contain all the information from the sensor, even if the image was cropped in-camera; images that have been stitched together from the camera can now have transparent edges; and more dynamic range information can be stored using floating point integers.
DNG is an open and widely used format, so now its up to the software makers and manufacturers to bring their side of things in-line with these new features.
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