Finding a camera's dead pixels
pgaviria
Registered Users Posts: 78 Big grins
This may be a little off topic. If it belongs to a different forum I apologize in advance, but it seemed like something you'd need finishing software to do so I thought I'd ask here.
I have been thinking about Ahmadinejad's insinuation in an interview that the girl who was shot during the protests after his election, whose death was video recorded and distributed all over the planet, was a set up because there is footage of her being followed by the same camera before she was shot.
Ok, this is not about politics but I was thinking that it might be possible to find out if two images were recorded with the same sensor by the pattern of the sensor's dead pixels. Is this realistic? How do you find dead pixels in a photo without looking at it yourself pixel by pixel? And if it is possible to do this, is it a requirement that the image has not been altered at all?
How about finding out if an image has been taken with the same camera at the same temperature? I am asking this other question because it could be an indicator that the picture was taken at the same time as another with similar noise. I know people who do astrophotography take blank shots to document the noise in the sensor which is dependent on temperature.
Anyone familiar with these things?
I have been thinking about Ahmadinejad's insinuation in an interview that the girl who was shot during the protests after his election, whose death was video recorded and distributed all over the planet, was a set up because there is footage of her being followed by the same camera before she was shot.
Ok, this is not about politics but I was thinking that it might be possible to find out if two images were recorded with the same sensor by the pattern of the sensor's dead pixels. Is this realistic? How do you find dead pixels in a photo without looking at it yourself pixel by pixel? And if it is possible to do this, is it a requirement that the image has not been altered at all?
How about finding out if an image has been taken with the same camera at the same temperature? I am asking this other question because it could be an indicator that the picture was taken at the same time as another with similar noise. I know people who do astrophotography take blank shots to document the noise in the sensor which is dependent on temperature.
Anyone familiar with these things?
0
Comments
http://forensicphotoshop.blogspot.com/
I know that I have a good link to a video on forensics and Photoshop, I'll see what I can dig up...
EDIT: Here it is -
http://video.google.com/videoplay?docid=-6117162361460615788
Best,
Stephen Marsh
http://members.ozemail.com.au/~binaryfx/
http://prepression.blogspot.com/
http://members.ozemail.com.au/~binaryfx/
http://prepression.blogspot.com/
I've never thought to look at fakes in that light before!!!!
My Web Site
Google have some great tech videos, some links are compiled here - and or search for more at various places around the web! Please let me know if you find some good ones too...
http://www.dicklyon.com/phototech/
Regards,
Stephen Marsh
http://members.ozemail.com.au/~binaryfx/
http://prepression.blogspot.com/
http://members.ozemail.com.au/~binaryfx/
http://prepression.blogspot.com/