How to insert a digital watermark?

July 17, 2005 10:15 PM

Does anyone know of a free way to insert a digital watermark (invisible watermark) into an image?

I am looking for freeware, or if its possible to somehow manipulate an image in photoshop to do it. I am aware of the possible use of steganography, but I am under the impression that it won't last if the image is resaved or resized. It doesn't need to be unremovable, just something your average image thief wouldn't remove just by resizing; etc. . .

posted by [insert clever name here] to media & arts (7 comments total)

If you want the watermark to be preserved by normal image manipulation (i.e. resaving as a JPG), it's going to have to be visible. Well, either that or embedded in a non-image portion of the file, such as the JPG/GIF comment field. This is also easily removed, though.
posted by knave at 10:29 PM on July 17, 2005

Watermarking technology generally falls within the category of steganography. Here are freeware watermarking tools and some more via Google.
posted by Rothko at 11:14 PM on July 17, 2005

Why not use the Digimarc plug-in that comes with photoshop - last time I checked it was entirely free to use yourself, the cost/subscription stuff was only for added-on goodies like their search engines searching the web for any unauthorized use of watermarked images.

The watermark plugin gives you the sliding bar option between strength and invisibility - at higher strengths, the effects become more noticable in a side-by-side comparison, but they claim someone can copy, then resize, then print out the image, then scan it into a computer, and the watermark will still work.

I use photoshop 7, maybe the plugin has changed since this version?
posted by -harlequin- at 11:47 PM on July 17, 2005

I just went and played with digimarc, it seems pretty good, however, either my memory is mistaken or something has changed - you are very limited in what information you can embed when you haven't paid. There are various flags and copyright notices and such you can use, but you're restricted to using numbers to ID the image if you haven't paid.

Quality-wise - at max strenth it's noticable on some images, all but invisible on others, and on some, perhaps even an aesthetic improvement :)
posted by -harlequin- at 11:55 PM on July 17, 2005

These Free PDF Tools Have a couple of 'add watermark' options - one with text, one with images. (Why it says 'NO WATERMARK' at the top of the page is confusing, however.)
posted by yoga at 6:53 AM on July 18, 2005

google's new picasa software lets you add caption data to the EXIF header. I doubt your average image thief would bother to remove that.
posted by cosmicbandito at 9:04 AM on July 18, 2005

Metadata headers like EXIF aren't very reliable for this purpose. They are often removed accidentally when images are edited and saved by non-EXIF-aware software.
posted by mbrubeck at 2:58 PM on July 18, 2005