The DNG Specification has been revised and the version number incremented from 220.127.116.11 to 18.104.22.168. This is not an area of frequent change given that the format has done a good job of addressing the progress of raw formats over the last three years.(The last update was finalized in February of 2005) This update addresses several industry requirements for the DNG format including the formalization of the concept of a “camera profile” and a metadata tag to validate your image data.
The definition of a camera profile for the DNG format as well as the allowance for multiple camera profiles to be embedded in a single DNG file will provide the industry with the ability to characterize raw data in an efficient and standardized format.(Think ICC profiles but for raw data)
Additional metadata tags have been defined for the DNG format including a field to indicate a ‘hash’ or the integrity of the raw data within the file, providing a valuable tool for validating the safety of your image data. A DNG file is comprised of three components: raw data from the sensor, metadata to describe the raw data and an embedded preview to represent your interpretation of the raw data. (See my earlier blog post on DNG if you need more background) Writing metadata back to a standardized file format like DNG is a common operation but many are concerned about the sanctity of the image data from the sensor. The opportunity to ‘fingerprint’ that block of data and check it from time to time to ensure that there hasn’t been any disk corruption or I/O errors is a significant step forward in ensuring the archival safety of your images. For the developer crowd, the DNG SDK has also been updated to reflect the changes to the specification.
The DNG Codec for Windows Vista users is also now available as a free download from Adobe Labs. This is our first release for the Windows Codec platform and before finalizing the release we’re offering it as a ‘Release Candidate’ on Adobe Labs. A release candidate is a version of the technology that is nearly complete but we would like the community’s help in ensuring compatibility across a wide variety of hardware and software configurations.
On a final note, If you missed it earlier, you’ll want to check out John Nack’s blog post on the DNG format submission to the ISO.