Is there software out there to manipulate quantization tables orspoof another camera?

Discussion in 'Digital Photography' started by billo, Nov 20, 2008.

  1. billo

    billo Guest

    I just bought a new Nikon D90 camera -- the first higher-end consumer
    camera I've ever had. A friend of mine was telling me that every
    picture I took can be traced back not only to my camera, but to
    roughly when I took it -- not on the date and time in the EXIF data,
    but a shutter count that acts like an odometer. He said folk could
    trace it back to my camera, at least to the model, by looking at jpeg
    quantization tables that are model specific.

    While I guess there's no big issue with someone tracing a photo of my
    cat I post on my website back to my camera, there's something about
    the libertarian side of me that just doesn't like the idea.

    Does anybody know of software (as always, preferably open source) that
    will spoof the quantization tables so that doesn't look like my D90? I
    guess I'm looking for the photography equivalent of macchanger
    software...

    Thanks!
     
    billo, Nov 20, 2008
    #1
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  2. billo

    Pat Guest

    If you are that paranoid, you have two good options. You could (a)
    print the image and rescan it or (b) steal someone else's camera and
    use that.

    Of course in either case, you still have the image on your computer so
    they can find it there.

    So ideally, I guess the best option is to shoot film, print the image,
    burn the negatives and then shred the pictures. That's the only real
    safe way to do it.
     
    Pat, Nov 20, 2008
    #2
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  3. billo

    Guest Guest

    all cameras will save the date/time that the photo was taken and some
    cameras even embed the serial number of the camera (i don't know if the
    d90 does that). while it's easy to determine that a d90 took the
    photo, it's not so easy to trace it back to you specifically.
    there are various utilities to strip the exif data entirely.
     
    Guest, Nov 20, 2008
    #3
  4. billo

    jaf Guest

    Mr. Bill,
    This news group is monitored by the Precrime Force of The United States Department of Justice.
    You are obviously planning to commit a crime and document it with your camera.
    Report to your local constabulary for persecution.
    Resistance is futile. You will be assimilated.


    John
     
    jaf, Nov 20, 2008
    #4
  5. billo

    billo Guest

    Yeah, I know I can strip the EXIF data. I want to spoof another
    camera, though -- for instance make it look like it was from a
    Canon....
     
    billo, Nov 20, 2008
    #5
  6. billo

    billo Guest

    Heh. Not a problem. I trust my government and know that they would
    never make any mistake about anything. I truly value the vision of
    our leadership and support them in all of there efforts. Honest. I'm
    the American version of the Chinese version of Andy Rooney! (see:
    http://www.theonion.com/content/video/china_s_andy_rooney_has_some ).
     
    billo, Nov 20, 2008
    #6
  7. billo

    Guest Guest

    so add exif data that matches what a canon camera would have produced.
     
    Guest, Nov 20, 2008
    #7
  8. billo

    billo Guest

    That's the tool I'm looking for...
     
    billo, Nov 20, 2008
    #8
  9. billo

    billo Guest

    One other thing I should add, by the way. In some cameras,
    particularly those that use a standard quantization table, the table
    itself may not be in the exif data, and instead must be
    probabilistically inferred from the image(s). Thus, say, to spoof a
    Canon, it might not just be a matter of modifying tabular data in the
    exif file, but of recoding the image itself.

    billo
     
    billo, Nov 20, 2008
    #9
  10. billo

    Guest Guest

    Guest, Nov 20, 2008
    #10
  11. billo

    billo Guest

    Thanks. I took a look at it and read up on the JPEG EXIF
    specification. I have a question in to CPAN to see if exiftool will
    write to the DQT and DHT tags; it doesn't look like it. But in any
    case, I now have a better handle on what I'm asking for -- a tool that
    will write to the DQT (FFDB.H) and DHT (FFC4.H) segments. The
    exiftool page lists a number of APP segments it writes to -- APP1-
    APP15, as well as others like SOF, but it doesn't look like it goes
    beyond 0xfe58, and not to 0xffdb or 0xffc4 ranges.
     
    billo, Nov 20, 2008
    #11
  12. billo

    billo Guest

    Ah, but I don't want to photograph naked children! I want to
    photograph naked FBI agents.

    billo
     
    billo, Nov 21, 2008
    #12
  13. billo

    billo Guest

    Actually, since this has come twice now in this discussion, let me
    give you a different hypothetical. Consider a person in a country
    where photographing the police is a crime. Interestingly enough,
    photographing the police in action will get you arrested in many
    jurisdictions even in the US -- even though such arrests are *usually*
    overturned eventually (Google for "arrested for photographing
    police"). So let's say that you are a person who has photographed the
    police doing something and want to release the image to the press or
    to an investigative journalist or to a dissident web page, but don't
    want to be accused of "Photoshopping" it (which would happen if the
    EXIF data suggested it by having an Adobe DCT or DHT area). Let's say
    you don't want the police to even track it back to your type of camera
    -- if they see you carrying a Nikon, it would be good if they were
    looking for a Canon.

    There are other reasons to be careful, particularly in some places,
    than child porn.

    billo
     
    billo, Nov 21, 2008
    #13
  14. billo

    billo Guest

    Just because people drive cars to rob banks doesn't mean you should
    ban cars. In general, knowledge is a good thing, and the fear of it
    is a bad one. All knowledge can be misused; that's not a reason to
    cling to ignorance.
     
    billo, Nov 22, 2008
    #14
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