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How to clear photos of unwanted Exif data

2012-08-12
by Olivier Cleynen

Every time I take a pic­ture with my dig­i­tal cam­era, the embed­ded soft­ware stores a large amount of infor­ma­tion along with the pho­to inside the file, con­tained in EXIF tags.

Some of that EXIF infor­ma­tion, such as the date and time the pho­to was tak­en, is very use­ful. Some of it is only inter­est­ing to pho­tog­ra­phy enthu­si­asts: it gives insight into the camera’s per­for­mance and the photographer’s adroit­ness and artis­tic deci­sions. A large bunch of the EXIF infor­ma­tion, such as the cam­era dis­tance to the focus point or how exact­ly the cam­era react­ed to the software’s orders, is entire­ly use­less. And some of that EXIF infor­ma­tion is out­right harmful.

I can­not see a good rea­son, indeed, for embed­ding the cam­era ser­i­al num­ber(!) or mys­te­ri­ous bina­ry blobs of infor­ma­tion with­in the pho­to file. As the EFF explains very well, a great deal of pri­va­cy is giv­en away when dig­i­tal fin­ger­prints are left on the pho­tos that we share. This is espe­cial­ly true today when the largest com­pa­nies on the Inter­net feast on our pri­vate infor­ma­tion, bas­ing their busi­ness mod­el on track­ing and read­ing through our lives and thoughts.

Things needn’t be this way. On a Lin­ux sys­tem (for exam­ple, Ubun­tu), eras­ing all EXIF data from a large batch of pho­tos is as easy as typing:

exiv2 rm *.JPG

This, how­ev­er, removes all the use­ful and poten­tial­ly inter­est­ing infor­ma­tion. I wrote a lit­tle script called JASESS which reads out the inter­est­ing EXIF tags, eras­es every­thing, and then puts this select­ed infor­ma­tion back into the file. An EXIF san­i­ti­za­tion of sorts.

Under any Lin­ux dis­tri­b­u­tion the script is run as follows:

  1. Down­load the lit­tle text file
  2. Make it exe­cutable (a right click → prop­er­ties → permissions)
  3. Dou­ble-click on it in the same fold­er as your photos.

Run­ning the script can also be made as easy as right click with­in your file brows­er, or typ­ing a sin­gle let­ter in your shell prompt.

I strong­ly encour­age any­one to at least briefly read through the script. I made great efforts to com­ment it exten­sive­ly, so it may be under­stood and cus­tomized by a begin­ner. Nat­u­ral­ly, feed­back is always welcome.

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(more by Olivier: articles, thermodynamique, fluid mechanics, mécanique newtonienne)