Hi all,
Suppose I copy an image I find online and save it into my photos folder. Then, from my photos folder I post that image on the Book of Faces. Is there a way someone can glean info from my posted photo in order to find where I originally got it from?
I ask not for nefarious reasons, I am merely putting together a fun little game and I’d like to eliminate cheaters.
Thanks,
mmm
Usually jpeg photos have EXIF metadata in them, which may or may not tell you something, depending on which metadata tags are present. However, facebook strips exif data from posted photos.
OTOH, you can search with something like tineye, and possibly figure out where the image came from.
Tineye and Google Image Search lets you find other versions of the same image, which sometimes lead you to their origins. It’s not a guarantee* but I have sourced images via Google frequently, a few times per month in fact. The fewer sources the harder it can be, but then again the more likely you’d pin it down exactly.
*Tineye hasn’t successfully found anything for me in years
This.
Also you can eliminate the Exif data by editing image in GIMP.
Also by taking a screen shot of the image and posting that.
But that’s creating a new image, typically much much lower resolution.
Fun fact: it’s not hard to find photos online that have geo-tagging info embedded in the EXIF data, locating the spot to a back yard.
Sooooo handy for stalking and harassment…
Heh. Actually, it seems to me that fewer pictures are geotagged than you might expect. Reasons:
A lot of pictures are taken with smartphones, which do generally have geotagging capability. However, Android’s camera app seems to have geotagging turned off by default - I don’t know about iphone - I use Android, and mine’s off. IMO, that’s probably the right default.
Some point and shoot digital cameras have geotagging built in, but, perhaps surprisingly, most higher end cameras do not. If you want your photos geotagged, you have to buy an add-on accessory, or use a GPS tracker or your phone to synch the photos later on the basis of time stamps.
The time stamp from the camera, and technical details such as model of camera, lens focal length and exposure are nearly always provided by a digital camera.
So, generally speaking, it’s the clueless idiots snapping pix of their family, their impromptu orgy or their naked spouse covering his/her face that are the ones likely to use a tagging camera, and probably not know about the feature or if it’s enabled. 
I have had success “defeating” Google image search by opening the photo in an editor and reversing it horizontally. I also re-size it slightly. When I do this, it no longer shows up on Google image search.
That’s a feature, not a bug.
If I were to post a pic to, say, Dropbox, to share it among those I know who may want to print it, it would be high-def, though I’d likely still strip the EXIF.
But posting a pic on some social-networking site, for instance, not a chance.
So is opening the image in GIMP and resaving it. Except, instead of lower resolution, it’s just lower quality.
You can just remove the EXIF data itself, if you wish. Personally, I use a program I already have for other purposes: FileOptimizer. It losslessly reduces the file size of a whole host of filetypes. (Though not PDF, despite supporting them.) It also has an option to remove EXIF data–though I’m not sure if it’s on or off by default.
Someone else mentioned flipping the image. You can also do that losslessly with JPEGcrop.
This is most excellent to know. I might be too lazy to carry it out, though.
mmm