I missed your last post so I assume you are referring to the watermark and preventing the use of your images, by others, without your permission.

Right now, I do three things to assert my ownership of an image and my lack of concent for the images to be reused without permission. The notices, in some cases, may not be fully official but they are expressions of my intent and desire that the photos still remain MY PROPERTY. First, I do put my innitials in an inconspicuous place so that my creation of the image is identified. Like an artist signing his painting or engraving on his statue, pottery or other sculpture. I also put a notice on my web page etc. or any other exhibition or publication indicating the illegality of copying my photos without my permission and asserting my rights and ownership to those images, making it abundantly clear that my posting of an image IS NOT to be misunderstood as a release into the public domain. There is a problem out there where some people think that the internet is a lawless place where all works are public property and fair game for anyone to use. The only works that I don't do the above with are simple illustrations of a thought that I might post to a board or newsgroup. Some of them are simple snapshots and aren't worth all of this fuss. Besides, contrary to what internet pirates might think, the copyright laws are VERY CLEAR, that any photograph, music, motion picture, art, ... is owned by it's creator UPON CREATION and copyright is AUTOMATIC. While it may not express specific protections for the internet, it does not say anything about art, music, photography... on the internet being public domain either. Lastly, I produce most of my images large enough for people to appreciate but small enough that they can not have any practical use for them.

http://members.aol.com/wmas1960/homepages/Vegas1.htm
http://members.aol.com/wmas1960/homepages/Vegas2.htm

If they try to use them commercially in any enlarged form they will look like crap. The above notices etc. will not stop someone from taking your images and reusing them. However, limiting the quality by compressing and keeping your images smaller will deter some. Puting your logo, name, innitials, right on the face will also deter but as was mentioned, will detract from the image. Note that while the compilation below may be rather large, the individual chips are too small for someone to really get a lot of value from. Once they crop them out, they will be awefully small. Incidentally, the image below was created with Adobe Photoshop. It is at least 25 different layers. The layout is one, Each chip is another and the shadows underneath are still others. Therefore, it is, in fact a compilation of 11 different photos.

This brings me to the last bit of advice I would offer. When you take digital photos, or create an image from a scan etc. or create something in a paint or photo editing program, always keep original copies of the unaltered photos or scans or final creations. They will contain date and time codes that will establish exactly when they were created. If you alter them, you are creating a new image and all those codes will change. If you make a simple copy of an image it will still contain the original codes. This is also good so if you loose an image or mess something up, you will be able to go back to the original. In relation to our subject here, the original images will be some of your best evidence that an image is yours. If your image has a date and time that predates someone elses, yours will clearly be original to theirs. So, if you take an 1024x768 picture of a chip, and 10 days later reduce it to 150x150, than the larger image will show a date code 10 days sooner than the smaller one. If some guy takes that image and puts it into his eBay ad a week later, he may end up with an image that is 7 days newer than the copy that you made and 17 days newer than the original. If you have the oldest file yours would seem to be the original. The only way someone can have an original as old as yours is if they had access to your actual original photos and made copies. If you only post photos that are altered, even if it is simply resizing, the image on the net will be dated older than the original.

The above is how I understand digital imaging works and is what I have noticed from my experience.