Digital Cameras embed several types of data inside the images you take, including camera manufacturer, date the picture was taken, and aperture, shutter speed, and focal length settings. These are called EXIF tags and are also called “metadata.” Here’s how to take advantage of these tags to embed your own copyright notice.

You’ll need the program exiftags to this excercise.

Let’s look at my picture trees.jpg‘s EXIF tags using exiftags:

$ exiftags trees.jpg
Camera-Specific Properties:

Equipment Make: OLYMPUS OPTICAL CO.,LTD
Camera Model: C40Z,D40Z
Camera Software: QuickTime 6.4
Maximum Lens Aperture: f/4.8

Image-Specific Properties:

Image Orientation: Top, Left-Hand
Image Orientation: Top, Left-Hand
Horizontal Resolution: 72 dpi
Vertical Resolution: 72 dpi
Image Created: 2003:12:07 15:49:06
Exposure Time: 1/500 sec
F-Number: f/5.6
Exposure Program: Creative
ISO Speed Rating: 100
Exposure Bias: 0 EV
Metering Mode: Pattern
Light Source: Unknown
Flash: No Flash
Focal Length: 19.80 mm
Color Space Information: sRGB
Image Width: 2272
Image Height: 1704

Now lets add a “Comment” with my copyright notice. Type:

$ exifcom -w "copyright Joe Blow" trees.jpg

Now let’s look at the tags again to see the new “Comment” field:

$ exiftags trees.jpg
Camera-Specific Properties:

Equipment Make: OLYMPUS OPTICAL CO.,LTD
...
...
Flash: No Flash
Focal Length: 19.80 mm
Comment: copyright Joe Blow
Color Space Information: sRGB
Image Width: 2272
Image Height: 1704

You can add your copyright tag to a folder full of images by doing:

$ cd /path/to/picture/directory
$ exifcom -fw "copyright Joe Blow" *

Another command line utility that changes exif data and comment fields is jhead. To add a comment, use the following command:

jhead -cl "my comment here" picturename.jpg