The DNG spec has been updated to v1.4 by the folks at Adobe, and it brings support for cropping, HDR, panoramas and lossy file compression. With these changes, maybe it's ready to replace JPEG in iDevices?
DNG, often known as a “digital negative,” is an standard spec for RAW image files from cameras. It's meant to be the plain text of RAW, openable in any RAW editor. More importantly for many, converting your RAW files into DNG will shrink the file size without losing any info.
RAW (and therefore DNG) aren't image files. Instead, they are buckets containing all the data from the cameras sensor, gathered at the time of shooting. And clipped to the handle of this bucket is a post-it note with various things like white balance, ISO and so on.
When an app like Lightroom or Aperture digs into this bucket of bits, it takes a look at that post-it and applies the white balance etc. at the time it renders the image. And when you tweak the image, the original bucket is never changed. Crops, exposure tweaks, even red-eye corrections and sharpening are all just extra notes written back onto that post-it.
The new DNG spec brings support for un-cropping (if you tell your camera to shoot square pictures for Instagram, but later decide that you wanted the full rectangular version of the picture, then you can). It does something similar for panoramas, allowing DNG to store the non-pixels arrayed around the edges of weirdly-shaped stitched-together panos.
Finally, it can also store the extra data made by HDR images. These files have more dynamic range (hence the name) than even 16-bit image files, and the new spec sets aside a place to keep this extra data.
But the biggest change is the inclusion of lossy compression. Lossy means that information is lost as the file size is reduced, like MP3 and JPG. Lossy DNGs are around a third the size of the original, but retain more flexibility in processing. Thus, you can still set the white balance after shooting without affecting quality, but you might not be able to correct a woefully underexposed image.
For true future-proofing, and maximum editability, you should stick with regular RAW or DNG. But these new Lossy DNGs are way better than JPGs, and very similar in size. Put this together with the iPhone's HDR and panorama modes, and Apple's love of open file formats and lossless editing, and it's entirely possible that DNG could oust JPG in future version of iOS.
Via DP Review
- Source Lightroom Journal