How to I remove metadata from a photo?

July 5, 2009 1:04 PM

How do I strip absolutely all information (metadata, file created on, etc) data from a digital picture?

I have some digital pictures. I need to make it so that absolutely no information can be gleamed from them -- what camera took them, when they were taken, etc. Is there an industry standard/government standard for removing this information?

posted by Damn That Television to computers & internet (12 comments total)

How I do it is as follows: Get Irfan View, open your image(s) (I'm not sure if there's some sort of batch mode for this). Shift+J. Near the bottom select "Clear all APP markers". Click on Start.

Doing this will not recompress your picture (which is nice if you have it in a lossy format like JPEG), and clean out all the EXIF data.
posted by bjrn at 1:08 PM on July 5 [1 favorite has favorites]

I think in any graphics app, if you select all, copy, and paste into a new document, you'll lose all EXIF and IPTC data that was set on the original. Obviously this won't scale easily if you've got hundreds of photos, although a program like Graphic Converter is scriptable.

ExifTools looks like it will let you set all this data in batch mode, as a command-line app. The page has links to GUI apps that build on it.
posted by adamrice at 1:16 PM on July 5

I would also expect that converting to a format that doesn't have metadata (BMP? and you'd want to choose a non-lossy format, which BMP is), closing your image application, and then converting the image to your desired format would do the trick.

Don't know your purpose for this so it may be worth pointing out that something like a criminal investigation or other detective work can infer things from extremely minor details of what's visible in the photo. And for a photo released on the internet it's possible that years or decades from now some kinds of analysis and cross-referencing may be done en masse automatically, especially things like matching any faces that appear in the photo to other images of the same person available elsewhere, so those sorts of things might get extrapolated and become searchable even if no one gets particularly curious about your photo.
posted by XMLicious at 1:25 PM on July 5

I just want to repeat that if your images are in some format with lossy compression (such as jpeg), you really want something which is able to strip the exif data without recompressing the file because that will mean you will get some quality loss. Like Irfan View, or ExifTools.

Of course, if a little bit of quality loss isn't a problem (or if they are in a lossless format), then saving your images in a format like bmp, and then re-saving them as jpeg (or whichever other format you like) would do the job as well.
posted by bjrn at 1:31 PM on July 5

Print screen and edit the image in MS Paint on a public computer?
posted by codswallop at 2:14 PM on July 5 [1 favorite has favorites]

Depending on how uptight you are about secrecy, you should note that camera image sensors have a noise "fingerprint" that may photos taken with the camera identifiable, in the same way that distinctive wear on typewriter's characters make it identifiable. I don't know how seriously to take this threat, or how effective the following techniques may be in mitigating it, but here's an article on the subject.
posted by Alterscape at 2:23 PM on July 5

ifranview has a batch processing option. under output format, choose "Options" and uncheck the exif data, etc.
posted by FauxScot at 4:12 PM on July 5

My preference for doing this is to save the image in PPM format. It's a lowest common denominator format with absolutely no way to store anything in it other than image size and pixel colours. Then reload from the PPM file and save it in whatever format you really need. Even then you have to be careful about saving, lest your image software sticks your name or the software name and version or something in some metadata thing somewhere.
posted by Nelson at 4:15 PM on July 5

Here you go - without having to change image viewers, add a big software package, etc. This is a tiny, VERY small footprint program that does nothing BUT strip metadata from .jpg and .png files. It's called "JPEG & PNG Stripper" (original, huh?). You can find it here:
http://www.steelbytes.com/?mid=30

I've used it for a couple of years and it works perfectly. Like you, I prefer to keep all that jazz private.

Good luck!
posted by Gerard Sorme at 6:09 PM on July 5

By the way, regarding my post above about JPEG Stripper - you need to use the German server, the U.S. server has been down a while, they need to change that.
posted by Gerard Sorme at 6:12 PM on July 5

If your adversary is very tech savvy, stripping metadata may not be enough to hide the model of the camera.

Just sayin'.
posted by qxntpqbbbqxl at 8:36 PM on July 5

Great answers, everyone -- thanks!
posted by Damn That Television at 12:25 PM on July 6