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DPP Solutions: A Look At DNG

On September 27, 2004, Adobe announced the Digital Negative Specification (DNG), a file format that was supposed to unify the cluttered atmosphere of proprietary RAW file formats by offering a non-proprietary template that would act as a universal raw file. The DNG format was released, free from any legal restrictions or royalties as an open-source file for hardware and software designers to generate, process, manage and archive RAW images for any program, from any camera, and easily accessible as an archive at any time in the future. Almost four years later, DNG hasn’t found the ubiquitous acceptance the industry had called for, but there’s growing hope for the future.

“When we came out with DNG,” explains Kevin Connor, senior director of product management for Adobe’s professional digital imaging products, “RAW formats had already been around for a number of years. We were becoming aware of the issues of having all these different file formats. We had this brewing problem with hundreds of different file formats that only exist for short periods of time and then become obsolete. It seemed to us that we were heading toward a management nightmare, from both an industry standpoint and a photographer standpoint.

“Our philosophy on this from the beginning, sort of my personal belief,” continues Connor, “is that eventually the proprietary system is just going to break. When we came out with the first camera RAW plug-in, we were supporting around 25 cameras. We’re now supporting more than 175 cameras—in other words, more than 175 different file formats. And when you’re talking about images, people don’t want to keep those images for just five or 10 years. Professional photographers want to know those images will be fine for 50 years—100 years—from now. If you think about the rate of new-camera introductions, how many new file formats will there be? A hundred thousand? It just seems that it’s going to reach a point when it becomes unmanageable. So our goal was to try to raise awareness of that—a catalyst for fixing problems sooner rather than later. I think we’ve definitely made some progress toward those goals, but it’s still an open question to me on how soon before things actually start to break down and we get the solution more widely adopted.”

Most proprietary RAW files are loosely based on the TIFF format. Image data is stored in exactly the same way, but the pixel data that it represents is slightly different. While a typical color file is three color channels—red, green and blue—a RAW file, in a sense, is comprised of only one color channel, with each pixel marked as a blue pixel, a red pixel or a green pixel. The RAW file, more or less, uses the TIFF structure to store that information, also adding EXIF metadata and other data. The difficulty is that once RAW files are developed as a proprietary, from a decoding standpoint, there’s uncertainty over which pixels are which. Manufacturer documentation is anything but open-source, which also makes deciphering a difficult process for those not in the know.

DNG comes along to fix this process by adding another piece of metadata that can specify which pixels are red, green and blue, as well as camera color profiles and other information that will do a better rendering of the file. The DNG file takes the original RAW image data and copies it, essentially untouched, as well as absorbing the additional metadata from the original files. Some data may transmit, but not always translate, so Adobe also offers the option for DNG to act as sort of an envelope, carrying over the entire proprietary RAW file into an admittedly bigger but untouched file, which then can be similarly opened by any DNG-compatible application.

DNG doesn’t actually restrict what companies can do. It doesn’t specify that files need to be captured or designed in a particular way. All it asks for is additional metadata that can describe the nature of the proprietary RAW data. A RAW converter, which Adobe also released concurrently without charge, then can read the descriptive information and translate it to DNG. Most importantly, the DNG specification can be updated, so once you’ve archived your converted DNG images, they can be opened at any point in the future.

So why hasn’t the market run with the system? Manufacturers are just fine with doing things their own way. Your Canons and Nikons of the world certainly don’t have plans to drop support for their own formats. As such, DNG compatibility isn’t enough of a concern for them to invest their time and dollars in producing models that are DNG-capable from capture. Smaller companies who don’t have the money to develop their own systems, on the other hand, have shown a prescient interest. Supporting DNG is a way that you can be guaranteed support, because it works right out of the box.

Adds Connor, “At this point, the biggest support we’ve received has been from some of the smaller manufacturers or some of the manufacturers that are new to the D-SLR realm. So we have companies like Casio, Hasselblad, Leica, Ricoh and Samsung, that have all done RAW formats in their cameras, natively captured. It’s not surprising that it would start there.”

Pentax, poised to become a major player in the market, is the latest to offer DNG capture in its K10D and K20D D-SLRs. Heavy-hitter software products, like Apple’s Aperture and ACDSee Photo Manager, among others, also offer DNG support, so momentum for the format is gathering.

Ultimately, though, Adobe wants to get larger-player support. Connor notes that if they had gotten DNG going a little earlier, there probably would have been an easier time getting the big boys to play along. If they haven’t jumped on board yet, with all of the benefits that DNG has to offer, then what will it take for larger companies to embrace DNG capture?

“We’ve actually started talking to ISO [International Organization for Standardization] of potential standardization around a new RAW format,” Connor says. “We’ve submitted DNG as something for them to consider. At this point in time, it’s sort of premature to speculate whether a formal standard will come out of that or not. Obviously, it’s a standardization process that can take a long time, with many parties involved and different viewpoints. The good thing is that there’s a discussion happening.

“I think that the largest camera manufacturers, Canon and Nikon, likely are going to be the last to adopt it, but that’s going to be the major turning point,” adds Connor. “I’d also say that even if all we had were all of the smaller camera manufacturers supporting DNG natively, that would be a positive thing because it’s still cutting down on the total number of different formats. But obviously our goal is to go broader than that.”

While software and camera manufacturers struggle to keep up with the onslaught of new file types, it’s a tough sell to convince an entire industry that the solution to too many formats is another format. Without every programmer and manufacturer suddenly going open source, though, the imminent danger of our images being lost in the shuffle of progress is just too frightening to ignore. At any rate, the only thing certain about the future is that it’s uncertain. If DNG can bring a little tranquility in the meantime, it’s worth some serious consideration as a RAW format that can be archived.

For more information about DNG, visit

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