[HN Gopher] Camera model identification based on forensic traces
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       Camera model identification based on forensic traces
        
       Author : a1eaiactaest
       Score  : 25 points
       Date   : 2022-07-04 11:30 UTC (1 days ago)
        
 (HTM) web link (www.sciencedirect.com)
 (TXT) w3m dump (www.sciencedirect.com)
        
       | cm2187 wrote:
       | How does that help? It's like identifying in which continent a
       | picture was taken.
        
         | semi-extrinsic wrote:
         | I'm sure it will be useful for law enforcement or a defense
         | attorney, if someone is on the record saying "I took this image
         | with my Model Z camera" and they can prove that's a lie, it
         | brings the rest of that persons testimony into doubt.
        
         | runlevel1 wrote:
         | I expect it's similar to knowing the make and model of a car
         | that was used in a crime.
         | 
         | Police aren't going to go around pulling over every one of
         | those cars. However, if a suspect is captured, it can be a
         | datapoint to help make the case.
        
           | bad416f1f5a2 wrote:
           | > However, if a suspect is captured, it can be a datapoint to
           | help make the case.
           | 
           | The paper talks about using this to go after people who are
           | creating CSAM. That's a federal crime, which means an
           | investigation will be conducted by federal agents. USAs have
           | a 93% conviction rate - they'll case build like crazy to
           | ensure they get a conviction. Any data point helps.
           | 
           | Plus, they might ask you if you took a photo with your phone
           | - say "no" and they prove you did, and you're also lying to
           | the feds, which is a felony itself.
        
         | kortex wrote:
         | Hardly. There's 7 continents (~3 bits of entropy), but
         | dozens/hundreds of camera models this technique (6-8 bits). And
         | it's hardly the only media forensic technique out there.
         | There's ways of extracting the time of day without metadata,
         | manipulation software chain, the lens used (sometimes down to
         | make and model), and tons more. Before you know it, you've put
         | a big dent in the ~33 bits needed to pinpoint a specific
         | person.
        
         | aeturnum wrote:
         | There are no single perfect solutions. Being able to identify
         | which continent a photo was taken in would often be useful.
         | Geolocation, even inexact geolocation, is an essential part of
         | intelligence work.
        
           | cm2187 wrote:
           | my point is that there are hundred of millions of users using
           | the same iphone camera. That looks like a very minor
           | datapoint to me.
        
             | anigbrowl wrote:
             | It's a point of correlation. Suppose you know person X in
             | your area has a tattoo of a skull on their right arm,
             | smokes Marlboro red cigarettes, is left-handed, and uses an
             | iPhone, and all this information is fairly recent. You
             | notice someone with a skull tattoo and decide to observe
             | them, the three minor details take the id from a possible
             | to a probable.
        
             | Ancapistani wrote:
             | True - but I might be the only person in my county using a
             | Fuji X-Pro3.
        
       | d4a wrote:
       | I could have sworn I read about this exact thing in Cory
       | Doctorow's novel Little Brother
        
       | Wistar wrote:
       | Can an image be completely re-created with an AI routine or
       | process that yields very high visual fidelity to the eye but
       | eliminates any camera signatures?
        
         | ampamp wrote:
         | yes! https://arxiv.org/abs/2002.07798
        
       | BLO716 wrote:
       | I'd say also if this interests you - checkout #OSINTION
       | #blackbadge training from Joe Gray!
       | https://www.theosintion.com/courses/ (also, I am not Joe Gray -
       | just lots to be learned from this category of investigation)
        
       | sharmin123 wrote:
        
       | radarsat1 wrote:
       | I think an interesting possible application of this is that a lot
       | of applications of video to 3D reconstruction, such as SLAM and
       | photogrammetry, require good camera intrinsics as calibration
       | input. Getting this information automatically seems to be
       | difficult, so lens calibration is an important step. This work
       | suggests to me that calibration information could either be
       | recovered directly from images, or the correct entry could be
       | automatically looked up in some large shared database, which
       | would really simplify things for certain applications.
        
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