On Tue, Nov 18, 2008 at 6:28 PM, Doug Franklin <[EMAIL PROTECTED]> wrote: > P. J. Alling wrote: >> >> Change the block of pixels in the Jpeg at the upper right hand corner, >> unrotated, and you'll change the encoding. Do it a couple of times and I'll >> bet it's unpredictable enough to screw this method all too hell. >> However, even if it doesn't let's see they used an example to identify >> cameras, used in kidnapings. > > I haven't been able to come up with a good use for this technique beyond > things like identifying the camera to use specialized (tuned) algorithms on > the image in question. Just identifying a camera model doesn't do much good > in nearly any other environment that I can think of. Still, it's > interesting to me that they can "see" enough artifacts of the demosaicing > algorithm to identify them uniquely. Hopefully I'll get the time soon to > read the original paper and see exactly what they're doing. >
It's also not going to be entirely reliable as there's a number of cameras out there which share sensors and processing systems and therefore will evaluate as the same camera (Nikon D3/D700, Pentax *istDS/DS2, DL, DL2, Sony A200/A300 and many P&S's). -Adam -- M. Adam Maas http://www.mawz.ca Explorations of the City Around Us. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
