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Adobe's Kevin Connor Speaks on Adobe's DNG Specification

By John Virata

When digital cameras first came out, there were an array of choices to choose from and an equally bewildering number of special file conversion applications that shipped with the cameras to translate the data captured by the digital camera to a format the computer could read for editing.

It was not uncommon for camera manufacturers to ship a camera that captures in a special JPEG format that only its special software was capable of reading. And the RAW format is another story. There is no unified format that could be read by most image editors and on top of this, there is no digital equivalent of a negative that could be used for archiving purposes. So this left a whole host of compatibility and archival issues that had not been addressed. Until now. Adobe Systems has introduced a file format that it hopes will address the issues of compatibility between digital camera manufacturers and software providers. The format, based on the current TIFF EP standard, is called Digital Negative (DNG). Adobe hopes DNG will be adopted by camera manufacturers and third party software developers to alleviate RAW file format compatibility issues that face the digital camera industry.

Why DNG?

At the same time the camera manufacturers have released increasingly more sophisticated digital cameras, they have also been tweaking the RAW file format for these cameras to the point that one camera RAW file captured with one camera is completely different from a RAW file captured from a different camera from the same camera manufacturer, rendering the conversion software that the camera manufacturers provided for a previous generation camera incompatible with a current generation camera's RAW files. This opens up a whole host of potential issues, making archiving for the future a half hazard practice at best, whereby your digital archives may or may not be read by the file conversion software, provided that the software would run on tomorrow's computers.

Adobe's release of the Digital Negative specification, if widely adopted by the camera manufacturers and software developers, would put the issue of archiving and compatibility to rest. “There is definitely a lot of segmentation with the RAW format,” says Colwin Chan, Ulead image editing product manager.  “We certainly support the idea of consolidating this format into one that everyone can work with openly.”

The DNG specification, according to Adobe, is built on two types of data; the actual unmolested image data captured by the digital camera's sensor, and the metadata that defines what that data is. The metadata, Adobe says, is the main ingredient in the specification that will enable a raw converter application to convert the file. As it stands today, RAW file formats differ amongst manufacturers, and software vendors must build customized versions of their applications in order to open the differing RAW file formats. Virtually every time a new digital camera is released, software providers such as Adobe Systems must rewrite their software applications to support the new cameras.

With a standardized file format, of which Adobe hopes DNG will become, the digital wheel would not have to be reinvented, and the software developers could put their resources into their applications feature wise rather than having to come up with RAW support for the latest digital cameras. What DNG does is it takes all of the different RAW file formats that are currently being produced by the many digital cameras that are in use and attempts to unify them into a format that can be easily read by applications that support the DNG specification. Adobe has also built DNG with the camera manufacturers in mind, enabling them to add their own proprietary metadata fields to the specification without harming the specification's intent, which currently Adobe is advocating as an open standard. The specification is posted on Adobe's website and is currently "free of any legal restrictions or royalties," which would enable the digital imaging community to incorporate the DNG specification into their digital cameras, printers, and software applications.

To get a better grasp of the DNG specification, DMN senior editor John Virata spoke via email with Kevin Connor, senior director of product management at Adobe Systems. At the time of this writing, Connor was at the Photokina trade show in Germany.

DMN: How long has Adobe been working on this archival format?
Kevin Connor: Adobe has been working on this format for almost a year, based on expertise we have built up over the past two years doing support for raw formats within our applications.

DMN: Were there other hardware or software companies that worked on the specification?
KC: We have been sharing the specification with manufacturers since the beginning of the year and soliciting their input.

DMN: What are the primary reasons that this format should be supported by the community?
KC: Adobe decided to spearhead the introduction of the Digital Negative specification to address a growing problem in digital photography workflows. Raw file formats are becoming increasingly popular for photographers because they offer increased flexibility, quality, and control compared to traditional JPEG and TIFF formats. Unfortunately, no standard file format existed for storing these raw image files, so each manufacturer had to design its own format.  With the contents of the raw file so dependent on the design of the camera, the tendency has been for manufacturers to make slightly different raw formats for each camera that they create. Over time, this has resulted in an incredible proliferation of new file formats. The vast majority of these formats are not publicly documented, making it challenging for third party software vendors to support them. With so many different formats, it's difficult even for camera manufacturers to support them all.  Designed to work with all cameras, the new Digital Negative specification ensures images will never become obsolete.

DMN: How will the community benefit from the Digital Negative archival format?
KC: DNG provides the following benefits to its users:

  • All the information needed for accurate conversion is publicly documented
  • "Private" metadata fields are supported, so manufacturers can still add extra metadata that only they can use
  • Gives users complete choice about what software to use
  • The format works with all cameras, thus it will never become obsolete
  • Eliminates waiting for compatibility fixes for users' favorite software
  • Easily adaptable to future technologies
  • Includes versioning scheme that allows the format to evolve as new features are developed

DMN: How will the Digital Negative Format benefit professional photographers?
KC: As a publicly documented standard, DNG will ensure the following benefits for professional photographers:

  • Immediate software support for new cameras
  • Choice of raw converters
  • Software vendors will know how to provide support for the format long into the future
  • Multiple companies have access to the same, basic information, ensuring consistency
  • Same format for different cameras means the same software can be used
  • No need to change formats when a new camera is purchased
  • No waiting for your favorite software to support the latest camera
  • Makes raw files easier to work with and therefore facilitates faster and broader adoption

DMN: Will this format be an open format controlled by a standards body or will it be a format controlled by Adobe?
KC: Adobe is committed to supporting this format long into the future. If over time, there is a consensus between various parties that it should be controlled by a standards body, Adobe is open to doing whatever it takes to make sure customers' needs are addressed.

DMN: How will third party software developers implement this specification into their applications?
KC: Software developers benefit from DNG in a number of ways. DNG helps to:

  • Create significant R&D savings
  • Implement a single format to support multiple cameras
  • Create better quality conversions
  • Eliminate the need to figure out "hidden" information in proprietary raw files
  • Minimize the need for more software updates
  • Ensure that DNG-compliant software will support new, DNG compliant cameras automatically

DMN: Will there be costs or royalties associated with the use of DNG in future third party applications?
KC: No, there are no costs or royalties associated with the use of DNG in the future third party applications. The DNG specification is being freely posted on the Adobe Web site without any restrictions, royalties, or legal agreements.  Anybody is free to download and implement the specification.

DMN: What are Adobe's long term hopes for this format?
KC: Adobe hopes that this new file specification provides a long-term solution to the increasing proliferation of camera-specific raw formats, which complicate shared workflows and create concerns about long-term archivability. DNG has been designed with enough flexibility to support just about any digital camera, and it can also evolve over time to keep pace with technology. Designed to allow for native support within a digital camera, it can also be used by photographers later in the workflow via conversion utilities. By offering a more universal approach for storing raw camera information, DNG simplifies the use of raw files for camera manufacturers and customers alike, and thus should be of interest to manufacturers of cameras, software, printers, and other hardware devices in the photographic workflow. For more information on the DNG specification, visit










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John Virata is senior editor of Digital Media Online. You can email him at
Related Keywords:digital negative specification, digital negative format, Kevin Connor Adobe Systems, Camera RAW, DNG

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