Forensic analysis of recent Victoria's Secret photo
hackerfactor.com
hackerfactor.com
'Error level analysis (ELA) works by intentionally resaving the image at a known error rate, such as 95%, and then computing the difference between the images. If there is virtually no change, then the cell has reached its local minima for error at that quality level. However, if there is a large amount of change, then the pixels are not at their local minima and are effectively “original”.'
From http://www.hackerfactor.com/papers/bh-usa-07-krawetz-wp.pdf, a lot of interesting stuff in there.
Even though, to the best of my knowledge, the photo is 100% real.
If you fiddle with the levels in Photoshop that section does look really suspicious (though Im no expert).
[I have no expert knowledge on photos, wolves, or the photographer in question. But I like a good bet, especially in the pursuit of science!)
If you clarify your definition of "real" then your bet may become more enticing.
I can't stop wondering about this one. I am probably biased towards wanting to believe, but would really like to see a forensic analysis.
- The wolf is huge, much larger than anything known to stalk the woods of BC (both of us are from BC).
- The amount of fur suggests that it's wildly out of its natural habitat - not one of the common wolf species, and probably something more Arctic than temperate.
- From his personal experience, wolf eyes reflect green, not yellow. Furthermore, you will only ever get the shine if you shine a light at it - like a flash - but the flash on the camera in question could not reach that far. In fact, the flash on that camera was not fired, which as a photographer I can corroborate. There is no way a flash was used in the making of this picture.
- There's some weird clipping in the wolf, and a fairly distinct lack of shadow, but neither of us are Photoshop experts, so that's neither here nor there.
IMHO the lack of flash is, to me at least, pretty damning. The claim is that the flash was what scared the wolf off - but as someone who takes a lot of photographs, there is no way that a flash was used in that shot, especially one from a point and shoot camera.
- Extreme brightness and blown highlights.
- Very flat image due to the fact that the flash is in-line with axis of lens, very few shadows, and what shadows you see is very hard.
That picture is very, very much an ambient light picture - there would be the tell-tale "zombie" skin tone from a point and shoot at that range, and the people would be lit up like lanterns, washing the relatively dark background into unrecognizability.
It would take a skilled photographer with an off-camera flash to pull off that shot without destroying the background, no way that was done with an ordinary point and shoot.
So we can at least be pretty certain that the EXIF data was faked :)
It could just be a camera with a crappy little flash that isn't showing up very much (it is outdoors, after all).
edit: From a reddit comment:
> Notice the focal length. The camera was set to its maximum zoom, and probably has an underpowered flash. Other than specular reflections off a piece of plastic (purse?) under the woman's arm and from the creature's eyes, there wouldn't be any visible effect from the flash.
I think it is very, very unlikely that the photo is faked. If that is the case, however, that makes it an interesting photo not just because of the subject matter, but because it is capable of making most people think it is fake even though it is not.
As far as the comments about the flash go, there is evidence for a flash. First of all, the tapetum lucidum is highly reflective (check out this photo of cats: http://bp1.blogger.com/_N9wtKAb3vvc/RdYLsh3L3VI/AAAAAAAAAA8/...), or do a search and you'll turn up some freaky examples (e.g. http://farm1.static.flickr.com/191/484118524_dce1f8c203.jpg)
Secondly, if you look under the arm of the woman in the foreground, you can see a reflection from a flash there as well, probably from a piece of metal.
The photo's been looked at by a lot of people but I have yet to see a criticism that enters the realm of the scientific. The best criticisms revolve around questioning whether or not it was a wolf, which I think is a much better line of criticism, since there is no way to be sure (but it does seem unlikely).
When I retold the story later, people laughed in my face. I guess I don't need to link to Snopes.
I'm just saying, one or two embellishments along the way can make all the difference in credibility...
the fact that we're arguing that the wolf lacks a shadow and has overly bright eyes might be a hint that it is real simply due to the fact that an original photoshop artist probably wouldn't include all those "abnormalities"
http://www.tinyappz.com/wiki/Error_Level_Analyser
and the result is
Doesn't appear to show any manipulation, though I really haven't looked at the implementation or paper to closely to know what I should be looking for.
Also, other than this possible screw up, this one of the most thorough photoshop analyses I've ever read.
"[Update 2009-12-27: There was some debate whether the second picture was the same model. I have changed the second example.]"
When I read that he used PCA to detect that they modified her bust, I really couldn't believe it. That is really impressive.
edit: I guess I should add a little background. PCA was used a good bit in computer vision (and data mining in general) when I was in school. You typically don't see it mentioned outside of those contexts.
From: http://en.wikipedia.org/wiki/Criticism
"The word critic comes from the Greek κριτικός (kritikós), "able to discern" , which in turn derives from the word κριτής (krités), meaning a person who offers reasoned judgment or analysis, value judgment, interpretation, or observation . ...
http://web.mit.edu/6.02/www/currentsemester/handouts/lecture...
I'm also not convinced on the lightening of the skin tone. The lighting is entirely different in both pictures, and I have friends who have shifted tone more than that after a summer of tanning. (edit: her hair is much darker as well)
-Ohh, let me see... a professional photo could be manipulated by Photoshop or Gimp...
-mmmmm. It's photoshop what had been used.
He is truly a genius!!