Of Digital Images, EXIF Tags and Privacy

Exploring the images posted on the Internet

Let’s Start with an Example

Let’s assume we want to download an interesting image found on the web:

http://www.hotelditalia.com/foto/villaggio-la-roccia-lampedusa-e-linosa-residence-agrigento-foto.asp

First Inspectionin Microsoft Windows

Once the image is saved in a folder,

Select the view: Thumbnails

And mouse over the image:

You should see something like

What we learn here

• Some graphics formats can contain “data about data”:

- These data are called Metadata - They are embedded in the document itself - They are hidden from casual viewing

• In the case of the JPEG format, the Metadata is structured using “EXIF tags”

• Educate yourself on EXIF Tags: Read at: http://en.wikipedia.org/wiki/Exif

From Wikipedia:The metadata tags defined in the EXIF standard cover a broad spectrum

• Date and time information: Digital cameras record and save the current date and time

• Camera settings: Static information (camera model and make), and Dynamic information that varies with each image ( orientation, aperture, shutter speed, focal length, metering mode, and ISO speed)

• A THUMBNAIL for previewing the picture on the camera's LCD screen, in file managers, or in photo manipulation software. Note: this thumbnail remains unmodified when the real image is retouched and saved (by professional products)

• Descriptions and copyright information

Graphics/Audio FormatsSupporting TAGS

JPEG, TIFF Rev. 6.0, and RIFF WAV file formats, with the addition of specific metadata tags

EXIF Tags are not supported in JPEG 2000, PNG, or GIF.

EXIF Tags are created by

Digital Cameras, including Smart Phones

Some Photo-Editing Software: Photoshophttp://en.wikipedia.org/wiki/Extensible_Metadata_Platform

The XMP Tags are used for “Describing the document””

(Example on the next slide)

Some Specialized Software applications (used for inserting proprietary information: copyrights, etc)

EXIF (XMP) Tags inserted by Photoshop

Displayed with

The Problem with EXIF Tags

They contain information (that can be private) that is hidden by most viewing software

They can be displayed using Special Viewers

Deep InspectionA RAW View of the File

Start Lister32, also available in the current folder

(Note: Lister32 is a stand-alone freeware file viewer supporting very large files and several display modes: click on “Options”)

In Lister32, open the image you have just downloaded

A (partial) View of EXIF Tags

displayed by OPANDA (Plugin for Firefox)

http://www.opanda.com/en/iexif/

What we learnt here

What Digital Camera was usedThe image was retouched on a MacintoshUsing Photoshop CS3The Date/Time of the Processing. . . and many more things . . .

All this information is stored in the JPEG file format.This file implements the EXIF file format that can store a lot of

information about the creation and processing of the image.

Is this impressive? maybe NOT compared to all the information that could be stored in a

file implementing the EXIF Standard!

Examples

Preliminary Conclusions

CAUTION is recommended when

- You enter your settings in your digital camera- You use your Smart Phone to take pictures that

you will later post on the web, if it is GPS enabled, the picture will include the geographic location

- Graphics files implementing the EXIF tags can stores a lot of information!

- Reusing images found on the web: they contain some form of evidence of the owner of the image

Bad things that have happened because the users were unaware of EXIF information (MetaData)

Read Cat SCHWARTZ story:http://graphicssoft.about.com/b/2003/07/26/techtvs-cat-schwartz-exposed-is-photoshop-to-blame.htm

Read Adam Savage’s story:http://www.nytimes.com/2010/08/12/technology/personaltech/12basics.html

MetaData and Social Web Sites

What Social Web Sites do with MetaData embedded in images uploaded on their web sites :

- Automatically remove- Offers the user to remove- Does nothing: the uploaded image retains

its metadata

What the User Wants

To have control on this information …

We need a powerful tool (possibly several tools) to edit and modify the EXIF Tags!

In the next slides we reviews several freeware products

The Solution of the Poor User

How to Modify the EXIF tagsThe solution of the “Poor User”

1) Editing the image with a file viewer and removing manually the unwanted information does not work: this corrupts the file and the image is no longer viewable

2) Load the image in a Picture Viewer/Editor and save it as a BMP, this removes all the EXIF tags

3) Now save again the image in a JPG format. The result could be a file of a larger size

Metadata come in Various Flavors

- Exif

- GeoTags (added by devices that are GPS enabled: Smart Phones)

- XMP Information

Options for ProcessingMetadata come in various flavors

- Displaying MetaData (All or Part)- Modifying the MetaData (All or Part)- Adding MetaData- Exporting the MetaData: Copy the MetaData to a file- Importing MetaData from a file into an image- Removing All MetaData, including the Thumbnail

Different Perspectives:Is Metadata GOOD or BAD?

- A “Digital Camera User” wants to post online some pictures, but wants to remove all personal information hidden in the picture, such as geographical information, use of a retouching software, OS running on the computer, original image before cropping

- A Professional Photographer wants to add “Copyrights Notes” - A Professional Photographer wants to keep track of the make /

settings used to take each images- A Professional Photo Retoucher wants to keep track of the

software used to process each image- A user wants to keep track of the geographic information of the

location where the image was taken in order to associate it later with a geographical map

The intention behind the embedding of MetaData is USEFULNESS, but if used without the awareness of the user, it is a great infringement on privacy!

Tools for ProcessingMetadata come in various flavors

- Commercial / Freeware- As a rule, their capabilities varies a lot from

product to product for processing the various components of MetaData

- Can process one image at time or can process batches

How to Modify the EXIF tagsThe solution of the “Educated User”

Use a “EXIF tags” Editor

You will retain the original quality of the file

Some comments on the capabilities of some Free EXIF Editors

Testing

EXIFER

EXIFER

Web Site:http://www.friedemann-schmidt.com/software/exifer/

Download Link:http://www.tucows.com/adnload/281273_106644.html

Note: - Last Release: 2002,- No longer maintained- Very good product

Exifer gives access to only a limited number of EXIF Tags

It lets you ADD Tags (Photographer’s Name, Retouching Artist’s Name, etc., but you cannot remove the existing TAGS

Displays several EXIF Tags in the Right Pane

EXIFER shows the image and the embedded thumbnail

EXIFER scan save the embedded thumbnail in a separate file for later inspection

EXIFER can remove the embedded thumbnail, this results in a reduced size of the JPG File

In our example:

566 Kb >> 543 Kb

Rating EXIFER

The Interface could be more intuitive

Does not display all the EXIF tags (such as those added by retouching software, e.g. Photoshop)

Testing

PhotoME

PhotoMEShows most of the EXIF Tags(But exiftool(-k).exe and Lister show more)

Shows the tags added by Photoshop

Does not allow modifying the Tags inside the file, but allows

PhotoME offers several options for Displaying the Tags

XNView

Free Portable Open-Source

XNView

Can REMOVE All MetaData

Can Export some MetaData

XNView

Can EDIT some MetaData

Deep InspectionAn Interpreted View of the File

For this exercise we use:

A freeware utility

exiftool(-k).exe

Available at:

http://owl.phy.queensu.ca/~phil/exiftool/ (Windows and Mac)

Deep InspectionA RAW FILE VIEWER

For this exercise we use:

A freeware utility

Lister

Available at

Removing Metadata TagsPros / Cons

Pros of Metadata tags:Metadata tags can be technically useful

Cons:File sizeThe user should know what s/he is doing when

using files embedding metadata

Removing Tags from JPG imagesFrom: http://www.fieggen.com/software/jpgextra.htm

The various yellow sections are all "extras", which are ignored by web browsers and JPG image viewing programs

Removing all the yellow "extras" and combining some of the green sections whilst leaving the blue section intact results in a much smaller JPG file, yet the resulting image will look identical to the original image because the JPG image data is completely unchanged.

Space Savingusing JPGExtra

Download at:http://www.fieggen.com/software/JPGExtra2_Trial.exe

Website: http://www.fieggen.com/software/jpgextra.htm

Files Size: 566 Kb >> 532 Kb ( - 34 Kb, 6%)

Space Savingusing MetaSripper.092

Download at:http://photothumb.com/metastripper/meta092.zip

Website: http://photothumb.com/metastripper/

Files Size: 566 Kb >> 543 Kb ( - 34 Kb, 4%)

Space Saving

Original ~24kB  

Example with a small file: http://www.rlvision.com/exif/about.asp

Original Photo: http://www.rlvision.com/exif/example_photoshop_original.jpgEXIF Tags removed: http://www.rlvision.com/exif/example_exif_tags_removed.jpg

Cleaning Tool: Exif Tag Remover 4.0

Cleaned ~3kB

Note: the Reduction of the file size is more dramatic with small files

Total gain: - 21 Kb (88%)

More on files Embedding MetadataDigital Fingerprinting

Many file formats contain some form of metadata tags

Notorious: Frontpage saves in the <head> part information about the computer where the page is composed

Resources

Raising awareness about inadvertent information sharing

http://icanstalku.com/

http://icanstalku.com/how.php#disable

Web Photos That Reveal Secrets, Like Where You Live

http://www.nytimes.com/2010/08/12/technology/personaltech/12basics.html

http://graphicssoft.about.com/b/2003/07/26/techtvs-cat-schwartz-exposed-is-photoshop-to-blame.htm

Stalking for Dummies

http://blogs.forbes.com/firewall/2010/07/19/researchers-show-how-twitter-twitpic-make-stalking-simple/

Metadata in Microsoft documents

http://support.microsoft.com/kb/q223790/

Notes by P Krolak

These notes are ideas to incorporate into the exercise

Case Study

We will use an image of a table set that was for sale in a mall in the summer of 2009. The image was taken by a smart phone and sent via email to a friend.

The Table set

First – Use the EXIF Tool

The Exif result

• The Exif tool confirms the date, time, and camera including the settings

• It also shows the geotag data

PhotoME

PhotoMe

• Using the current version examine the table set photo

• We display the GPS data and we note the histogram information on the left.

PhotoMe

• Note the brower, image display, and image editing tool icons at the top of the window. Click and the image opens in the tool.

• For finding the portion of the metadata to display in the main window click the button for the section of the meta data that is to be examined.

GeoSetter

•GeoSetter allows us to open the metadata and edit it. •The Geotag metadata can add, edit, or remove the lat/longitude •The final step allows us to export a KML file to embed the picture in a Google map or Google Earth

GeoSetter

• Download from http://www.geosetter.de/en/

• GeoSetter is a freeware tool for Windows (XP or higher) for showing and changing geo data and other metadata (IPTC/XMP/Exif) of image files (e.g. images taken by digital cameras).

Step 1

• Click [Images] and open folder.

• Select the image to edit.

The GeoSetter display

The toolbar and the three parts of the display

• The working images – the highlighted blue image, the table set with EXIF data shown

• The image of the table set.

• The map with the purple marker showing the location of the photo.

Edit Step [Images]/Edit image

• The image is missing the location information to go with the lat/long

• The location is gotten from the web.

The Edit of the EXIF

• If the Geotag is missing the data can be added to the file.

• Suppose that you have photos without geotag that you want to enter data for you could use http://code.google.com/apis/maps/documentation/javascript/v2/examples/geocoding-reverse.html to point to the map where the photo was taken and get the address, the lat long etc.

• If the Geotag is missing the data can be added to the file.

• Suppose that you have photos without geotag that you want to enter data for you could use http://code.google.com/apis/maps/documentation/javascript/v2/examples/geocoding-reverse.html to point to the map where the photo was taken and get the address, the lat long etc.

• If the Geotag is missing the data can be added to the file.

• Suppose that you have photos without geotag that you want to enter data for you could use http://code.google.com/apis/maps/documentation/javascript/v2/examples/geocoding-reverse.html to point to the map where the photo was taken and get the address, the lat long etc.

Locate the site of the photo on the google map.•Locate the site of the image on the map provided.•Click on the location.•Record the data using the Geosetter tool image edit

http://code.google.com/apis/maps/documentation/javascript/v2/examples/geocoding-reverse.htm

http://code.google.com/apis/maps/documentation/javascript/v2/examples/geocoding-reverse.htm

An easier to use Geocode Site to get latt/long and zipcode from and address

Below the map you are asked for an address (two if you need directions)

http://www.geocodezip.com/example_geo2.asp?addr1=98122&geocode=1

Click on the images/Export to Google Earth

The KLM file will open in Google Earth

Locate the image and click on it

The image is now in Google Earth

Sources of GeoTagged Data

• Smart phones and tablets with cameras

• Cameras with GPS

•

Sites with GeoTagged Photos

• http://www.geospatialexperts.com/sampledata.php

• http://www.panoramio.com/

• http://www.flickr.com/

References for research

• Geotagging using iPhone or Android geotagging --http://www.geotagphotos.net/docs/geotagphotos-userguide-2011-01.pdf

• Google maps (lat, Lon) http://www.gorissen.info/Pierre/maps/googleMapLocationv3.php

References Geotagging Devices

• http://paulstamatiou.com/review-eye-fi-explore-geotagging-sd-card

Reference

• Reverse geogode example http://viralpatel.net/blogoogle-map-reverse-geocoding.htmlgs/demo/google-map-reverse-geocoding.html