You’ve just taken an amazing photo — perfect for a magazine cover.  You post it to your website, share it with friends and a few photo sites, and are confident that an editor from a major magazine will be calling soon once they see it and get your contact info.

You’ve updated the image’s metadata with your contact info, embed your watermark ID and begin posting to the web. Then you notice on some sites that not only has your metadata disappeared, but the watermark is no longer readable. Even worse, someone has copied it onto their blog, resized it with no attribution and the watermark is unreadable. It seems unlikely your image will be on any cover soon since your ownership and contact info are no longer attached to your photo. So what’s causing all your info to disappear?

I know that you tested the watermarked image you posted since you’ve read my earlier blogs and the Digimarc Watermarking guide. You feel pretty good since the guide says for most images that using a default setting of 2 and a  JPEG medium image quality of 5 should allow you to read a the watermark if its been resampled down to 60% or up to 200%  of its original size.

So something is happening to your image that is stripping away your metadata, image data and the watermark when it’s on the web.

There is a common phenomenon that can cause these problems, posting a high res image. While the high res image allows your intended audience to zoom in and marvel at the details, it can also create some unforeseen problems. Believe it or not, too much image data can be the cause of missing metadata and the watermark.

Let’s say you uploaded a 6” x 4” photo at 240 dpi which is great for zooming in. This size can make a nice photo print and will probably still be under a megabyte in size.

If I were to download this image for my blog, I would simply resample the image to 72 dpi before reposting it to the web since a small file will meet my needs. I’m also going to recompress the image using JPEG. The immediate effect of the resampling is to leave only a 1/3 of the original image data and watermark (240dpi/72dpi = 33.33%) and then JPEG compression will remove some more of what’s left of the image and watermark. As you can see, just re-sampling the image to 72 dpi has already exceeded what the watermark was designed to survive; add the JPEG compression and you’re well past much hope of reading the watermark. If I happen to use an image editor other than Photoshop, I also strip away metadata since the application probably does not support Adobe’s metadata format.

Most social network sites automatically resample to a minimum size and will recompress your images when you upload, often stripping the metadata as well as removing large chunks of your original image data and watermark. Since social network images are intended for web viewing only (and not very critical viewing), the recompression is often very high.

Even photo sharing sites will often leave your images at your original resolution for a short period and then resample them unless you purchase an upgraded account.

You can see posting those higher resolution pictures has actually undermined your efforts to manage your images on the web. There are some simple solutions to help keep your image data intact, find your watermarks after they’ve been altered and maybe even detour those folks who would forget to provide attributions of the images they are using.

1. Don’t post really large image sizes online. That 8” x 10” image at 96dpi has lots of data, just like the high res smaller sized image at 240 dpi, allowing it to be resampled and used at smaller or larger sizes quite easily
2. If you want the details of a high res image to be available, select them as separate images and watermark them as well. Posting a full view of the image at 4” x 6” and 2 to 3 close ups at 4” x 6” limits the available quality of your images to be resized
3. Watermark images at sizes that are already optimized for web viewing. I.E. 72-96 dpi at 100%.
4. Use a higher watermark durability setting. Visually, a durability setting of 3 or 4 isn’t noticeable on many images
5. Use higher image quality settings when applying JPEG compression. By posting a JPEG image that is a slightly larger file size it will have more of the original image data and watermark in it.  That image will have a stronger watermark to aid its survival of resampling, cropping and recompressions that are part of being redistributed on the web
6. Visual watermarks can be very useful and help detour those with lazy plagiaristic tendencies.  Who really wants to spend 5-15 minutes removing an embossed name from a small image?

These tips won’t keep social networking sites from resampling and compressing your images to super small sizes, but you’ll have a much better shot at reading the watermark afterward if they don’t remove/resample away 50% or more of your image when you upload it.

There’s no guarantee that anything can keep a serious plagiarist from reworking your image until they can post it without you being able to retrieve a watermark or metadata. And while we keep improving the Digimarc watermarking technology so it eventually can remain within your image until it is changed and distorted so much that the image is virtually unusable, regardless of resolution, you can help by employing some of those tips. That way when your image is being shared on a photo site or someone’s just posting your image on their blog, the odds of identifying it as yours should increase greatly. 

With a little luck, that magazine editor will call after all...  If they do, don't forget your favorite blog writer would love to hear about it and so would I.