Wednesday, February 28, 2007

On “The Most Culturally Significant Feature” of Canon’s new 1D MkIII

by Micah Marty

Completely overlooked in the online fuss over Canon’s new flagship SLR was the incorporation of a significant new capability: the embedding of inviolable GPS coordinates into “data-verifiable” RAW files.

(In 2003 Canon introduced the process of “data verification,” an encryption process that reveals even the tiniest post-shutter changes to a photograph or its metadata. Nikon introduced its own comparable system of “image authentication”—with GPS capabilities—with the rollout of the D2Xs last July.)

Why is the ability to embed inviolable GPS coordinates “culturally significant”? Because it means that digital photographs can now be more tamper-proof than film photographs ever were. Offering a way to make digital photographs harder to undetectably manipulate than film photographs are is a big deal in the history of photography: even as millions of digital photographs are being made around the world every hour, film still enjoys a reputation for being “more trustworthy” while “digital” is considered easy to fake.

Some quick background
With film, a manipulated image can be rephotographed far from the original scene, under studio conditions, to produce a new negative that will fool at least some of the people some of the time into thinking they’re viewing an undoctored original. A similar process is possible with digital cameras, creating a new digital file by rephotographing a manipulated image under ideal studio conditions. (How often these scenarios are actually likely to occur isn’t as important from a “trustworthiness” perspective as is the widespread awareness that they can occur even once in a million photographs.)

When a “data-verifiable” RAW file has inviolable Global Positioning System coordinates embedded in it, however, it’s a different story. In order to match the embedded GPS coordinates of the subject depicted, the rephotographing of the manipulated image would have to be done at the original scene, using a plausible lens—because focal length is also embedded in the metadata—in order to not raise suspicion. If the GPS data embedded in the “new” digital photograph is inviolable, then carefully rephotographing a manipulated image without fear of later detection becomes almost impossible with many common subjects.

Could the rephotographing challenge get any tougher? Actually, yes. If not only focal length but also focus distance is incorporated into the inviolable metadata—as it is expected to be at some point soon—then the rephotographing of manipulated images of most wide-to-normal scenes shot at any distance greater than a few feet would be essentially impossible. Embedding focus-distance data means that the manipulated image to be rephotographed couldn’t be downsized and reshot at a macro-copying distance but rather would have to be rephotographed at the actual size and distance as the subject depicted in the photo.

Part of a larger industry trend
Canon and Nikon aren’t the only ones developing methods for checking how much digital photographs have been manipulated. The CEO of the worldwide news agency Reuters announced in December that his organization is working with Adobe and Canon to develop a method of “permanently embedding [in the file] an audit trail of changes made to a digital image,” a process which they hope will become the industry standard. (Reuters, you may recall, got stung last year after they disseminated to news outlets a manipulated image sent from a freelance in Lebanon. Credibility is a news agency’s lifeblood, so Reuters can’t afford another embarrassing incident like that one.)

Of course, “audit trails” and “GPS verification” can’t address problems of staged photos and other circumstance-related deceptions. Those are as old as photography itself and will always be possible with any secondhand representation of any event, in any medium (written, audio, or visual). But the advances described above do squarely address one huge variable in photography’s “trustworthiness” equation—undetectable manipulation of the photograph after it is taken—a variable which, as noted earlier, happens to be the most troubling aspect of “digital” for much of the general public.

Not just for photojournalists
Should photographers who aren’t photojournalists care about all of this talk of “data verification” and “proof of non-manipulation”? The good news is that they don’t have to ever make use of these technologies but they can whenever they wish to.

Only in news photography is something like an inviolable “audit trail” likely to ever be a requirement—and even then, only from one’s publisher, not from any larger entity (unless perhaps the photo is entered in a contest, in which case the contest sponsors may ask for an audit trail).

On the other hand, there are plenty of photographers of almost all subjects who are tired of viewers asking about every impressive photograph, "Was this picture manipulated?" It isn’t hard to see the appeal of a process that would let those photographers easily prove that it wasn't.

Should be interesting times ahead….

Micah Marty, a Chicago-based photographer, is the founder of (“The ‘Nonfiction’ Label for Photographs”). For more on “data verification,” see Those who want to know more about where TrustImage is coming from might start with "Photo Manipulation 101" or with the short essay on "Celebrating the Wonder of a Moment."

Posted by: MICAH MARTY

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