Background

Digital Negative (DNG) file format is a royalty free RAW image format designed by Adobe Systems. The DNG format and the free availability of the DNG Converter was announced on September 27, 2004.  The Digital Negative file format is a response to demand for a unifying camera raw file format. Digital Negative is based on the TIFF/EP format, and mandates use of metadata. All Adobe photo manipulation software (such as Adobe Photoshop and Adobe Lightroom) released since the announcement support DNG. Adobe is submitting DNG to ISO (International Standards organization) for standardization. DNG has yet to be accepted as a national standard.

 

The current problems

Archiving, created the need for a common file format for digital photographic files. In the early days, digital photography files were mainly in JPEG format and the need for a common file format was needed to assure file access (backward compatibility) years after the image is made. Backward compatibility is a huge user and software maker problem. Software companies usually drop backward compatibility after four to six software updates and replace program intrinsic compatibility with a file converter converting obsolete RAW file format into the current file format.

For instance, I started to use Microsoft Word in the early eighties and updated once every second or third release. As versions accumulated, the code needed to convert the older version files apparently becomes unwieldy and is substituted for a separate (free) downloadable converter. Adobe Pagemaker, Microsoft Word and many others went that route to provide data file backward compatibility for their older program versions.

Trying to avoid this, Adobe generated the DNG format in the hope the camera manufacturers would adopt it and solve the user backward compatibly problem. That, has not happened yet! The reasons are not clear. It could be, that camera manufacturers, at least the big ones, like to preserve the ability to improve their RAW formats and keep the  improvement classified and within the capability of their own RAW converter. Yet, they do pass-on any RAW format changes to Adobe who incorporates it into a new DNG release!  The camera manufacturers have to provide backward capability for their own products and force third party photo application software makers to adapt the changes to stay compatible!

I run into this problem over and over again. Recently I obtained a Canon 50D and made some test images.  Photoshop CS2 and DXO 5.3 both, could not process the images. The 50D Raw format was slightly different then that of previous digital Raw format of cameras in the same line.  Being a Photoshop CS2 user, I had to convert the images into DNG format. DXO and other similar software were useless until the release/update a few months later. I guess I could have solved the problem if I would have purchased a Photoshop update for a few hundred dollars. A camera based DNG format would have solved this problem much simpler and much cheaper for everybody.

Hoping for industry cooperation

Archiving digital images is a huge problem and, at the moment, without a good solution. What is archived today may not be retrievable tomorrow and that is something to worry about!  In  the old days, negatives were subject to time related deterioration. Now, archived images are depending on regular time cycle conversion or, maintaining a library of older process software versions or converters. God forbid if a change in processor architecture comes about requiring you keep one or two laptops with older processors to assure image retrieval. Far fetched? Maybe, but some standard must be accepted to avoid confusion and disappointment!

Another problem seems to be the DNG format itself. There is information, indicating loss of color data when converting DNG into TIFF. DNG is based on the TIFF/EP structure and I would like to see this "loss of color data" explained.  After all, many photo enthusiasts have already converted and a warning not to destroy their originals would be than be justified.

Regardless the above, there is some progress. Several camera makers, (Leica, Casio, Hasselblad, Ricoh and a number of Canon cameras can now shoot in DNG format. Adobe, who invented the concept is saddled with the (what is now a by Adobe paid for service) job of maintaining backward compatibility.

RAW processing software generated by the individual camera makers has always been a way to process RAW images however, many photographers prefer software they are accustomed to and often the new version is late or goes for another price. Of the many RAW processors, only a few are "on the ball" and update their software immediately when a manufacturer announces a new camera with modified RAW format. Much to my surprise, RawTherapee, a very capable RAW processor, seems to be one of the first ones to adopt modified RAW formats. This software is written by a group of Hungarian photographer/programmers with an excellent price, it is free but depends on donations to survive. See www.rawtherapee.com