Posted on 08/21/2006 4:00:38 PM PDT by billorites
PHOTOGRAPHY often blurs the distinction between art and reality. Modern technology has made that blurring easier. In the digital darkroom photographers can manipulate images and threaten the integrity of endeavours that rely on them. Several journalists have been fired for such activity in recent months, including one from Reuters for faking pictures in Lebanon. Earlier this year, the investigation into Hwang Woo-suk showed the South Korean scientist had changed images purporting to show cloning. In an effort to reel in photography, camera-makers are making it more obvious when images have been altered.
One way of doing this is to use image-authentication systems to reveal if someone has tampered with a picture. These use computer programs to generate a code from the very data that comprise the image. As the picture is captured, the code is attached to it. When the image is viewed, software determines the code for the image and compares it with the attached code. If the image has been altered, the codes will not match, revealing the doctoring.
Another way favoured by manufacturers is to take a piece of data from the image and assign it a secret code. Once the image file is transferred to a computer, it is given the same code, which will change if it is edited. The codes will match if the image is authentic but will be inconsistent if tampering occurred.
The algorithm is the weapon of choice for Hany Farid, a computer scientist at Dartmouth College in New Hampshire. Digital images have natural statistical patterns in the intensity and texture of their pixels. These patterns change when the picture is manipulated. Dr Farid's algorithms detect these changes, and can tell if pixels have been duplicated or removed. They also try to detect if noise—the overexposed pixels within the image that create a grainy effect—was present at the time the photograph was taken or has been added later.
However, forgers have become adept at printing and rescanning images, thus creating a new original. In such cases, analysing how three-dimensional elements interact is key. Long shadows at midday are a giveaway. Even the tiny reflections in the centre of a person's pupil tell you about the surrounding light source. So Dr Farid analyses shadows and lighting to see if subjects and surroundings are consistent.
For its part, Adobe, the maker of Photoshop software, has improved its ability to record the changes made to an image by logging how and when each tool or filter was used. Photoshop was the program used by the journalist fired by Reuters; his handiwork left a pattern in the smoke he had added that was spotted by bloggers. Thus far the internet has proven an effective check on digital forgery. Although it allows potentially fake images to be disseminated widely, it also casts many more critical eyes upon them. Sometimes the best scrutiny is simply more people looking.
"Several journalists have been fired for such activity in recent months"
and several have received awards for their frauds.
Almost all my sports photographs are cropped, have unsharp mask applied, and have the levels adjusted. The photos are also resized for different purposes. Web photos are the smallest, newspaper larger, and prints for sale use the original size. All of these are "editing" which could show up as an "altered photograph" by these tools. The rule of thumb is that for work being presented as news, you can't do something that alters the integrity of the image. Sometimes the rules are a little weird. For example, it's always okay to crop someone out of a photograph, it's not okay to use the clone tool to remove someone from a photograph. You can use a shallow depth of field to blur the background, but you can't use the Gaussian blur tool to blur the background.
The tools listed in this article will depend upon the integrity of the agency, as the agency will not release the unedited photo. As a sports photographer, the only thing I have to sell is my integrity. If word ever got out that I was doing something to doctor photos, I'd never sell another photo to a newspaper.
There are a couple of problems with many news agencies. One is that there is such an appetite for images that they shovel them in and out, frequently without review. Any cursory overview of the pulled photos should have revealed that they were fake. They simply weren't reviewed, or were given only a cursory glance. The second problem is that many agencies are so involved in advocacy journalism, that they accept things that support their viewpoint without giving them careful scrutiny.
Hey, I saw that guy in a Kinko's in Abeline a few years ago.
hash function (or hash algorithm) is a way of creating a small digital "fingerprint" from any kind of data. The function chops and mixes (i.e., substitutes or transposes) the data to create the fingerprint, often called a hash value. [...] the equality of two hash values ideally strongly suggests, but does not guarantee, the equality of the two inputs. If a hash value is calculated for a piece of data, and then one bit of that data is changed, a hash function with strong mixing property usually produces a completely different hash value. [...] A well designed cryptographic hash function is a "one-way" operation: there is no practical way to calculate a particular data input that will result in a desired hash value, so it is also very difficult to forge. Functions intended for cryptographic hashing, such as MD5, are commonly used as stock hash functions. Functions for error detection and correction focus on distinguishing cases in which data has been disturbed by random processes. When hash functions are used for checksums, the relatively small hash value can be used to verify that a data file of any size has not been altered.
Yes, basically don't trust anything from AP or especially Al-Reuters.
Ansel Adams did a lot of burning and dodging in his film lab. Is that cheating? No.
It is only wrong when it is a news item and is deliberately altered to misrepresent a FACT. It is not wrong if manipulation was just done so it would look better published or printed because the photog didn't nail exposure right. Cropping for artistic purposes isn't cheating either unless you crop something that would distort a viewer's perception of the news item.
The value is that if you still have a copy of the original, right from the camera's memory card, you can prove that that original image is unaltered. If the published image in question is only lightened and cropped from the original, then you can "prove" that that's all that happened to the photo after it left the camera.
2) See above.
If journalists were interested in allowing people to confirm the veracity of their photos, they could submit timestamps and hashes of them to a service that would publish that data immediately. Anyone who wanted to could periodically retrieve digitally-signed copies of the hash lists (there are a variety of ways to handle this). If an event happened at 14:23 GMT on a particular date and the hash value for some photos appeared on the server at 14:45, that would prove that the photos whose hash value appeared on the server existed at 14:45. It wouldn't prove that someone didn't do a really quick editing job, or even produce the photos before the event, but it would tend to add considerable credence to their veracity.
As for dealing with a desire to allow people to confirm the veracity of photos without wanting to release full-resolution unedited copies, the solution is simple: as soon as the photo is taken, generate copies at a few different resolutions and store the hashes for all of them.
BTW, if a hash function is regarded as non-reversable, it wouldn't be necessary to clutter up the server with separate hash functions for every photo. The photographer could simply produce for himself a list of all the hashes, and upload the hash of that list. He could then distribute that list to anyone he wanted to be able to confirm the photos' veracity.
In the days before digital photography, camera negatives were generally regarded as uneditable; anything one wanted to change would be adjusted either on prints or on copy films (positives or negatives). Although it is possible to alter camera negatives without fakery being apparent in prints made therefrom, an examination of the negatives themselves would reveal the alteration clearly. Further, most photographers prefer to avoid altering camera negatives directly because there's no way to 'undo' mistakes.
I would expect respectable news organizations would have regarded with great suspicion anyone who submitted photos without allowing the original negatives to be examined even in his presence. I see no reason they should not likewise regard with suspicion anyone who refuses to provide an unedited camera file.
Or any of the rest of media. A bunch of folks I know attended a rally back in the early 90s. A good-sized rally, a couple hundred folks downtown the day after Thanksgiving. There were a dozen fur protesters at the same place. Guess what? The fur protester group made the local TV news that evening and was named -- but the ralliers' signs were blurred, making it look like they were fur protesters too.
A wake-up call, as if I needed one by then.
It's the rare picture of mine that isn't improved by cropping, adjusting levels, maybe a little sharpening...
I take it as a given and always expect to see some post-production work.
What I object to is the editorializing that can occur in PP.
Cut and paste dead babies, Israeli tanks being added, etc.
So one of the 150 readers of the NYT looks at a picture of Lebanon burning. It's a fake picture. How will the readers know the "CODE" doesn't match?
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