There IS no "tasteful way" to watermark a on-line photo. It's always there, in your and the viewers face and no way to get around it.. Well, there are a few...
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1 - Don't have one. It will not stop copying and depending on where the mark is, it can be cropped out anyway.
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2 - Make it small and then it's easy to clone or crop out. Put it in multi corners and/or places and it looks like your photo has the pox...
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3 - Invisa-tag it. There are programs that hide your Copyright into the very structure of the jpg and it is coded where only you and your program have access to it. It is NOT in anything that can be seen, change or deleted. Images are made up of binary code, 0's and 1's. These programs add a small line of code, of their own, of your choosing, and slip it in a area that is not harmful to the photo in any way. Even if they have a machine language editor it would take forever to isolate the code from thousands of lines, and then it would only be a string of 0's and 1's hiding with countless ten's of thousands of others 0's and 1's.
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4 - Don't post anything over 800x600 pixels, ever. Pictures for posting should be compressed (re-saved) smaller (800x600) as well as have the compression level jacked up a bit, and this depends on YOUR Image Editing program. I find around 45% works well. The compression and physical size all but ruins the image for anything BUT on-screen viewing. Not too big to do anything with and never good enough to make prints from.
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5 - Just don't do it..! No way is safe. If they want it, it's right there to take. Don't want it taken, don't put it there.
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Then, being lucky to ever see your work elsewhere.. Oh, it has happened and the person has contacted the web master of where the image was, and it's gone. They do not want a suite filed on them for holding 'stolen intellectual material' so they usually remove it fast, UNLESS the web host and site are off shore (another country). Then it's good luck..!