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