Rosalind - 10:46 am on Feb 3, 2010 (gmt 0)
BTW, how to automatically embed watermark to image when it serve to display?
Best if it doesn't need to modify html or php.
You can use php's image functions to add a watermark. Or you can open your favourite image editing programme and use the batch processing and/or script functions to speed up the process. It's worth looking into this if you have lots of images.
However watermarking only goes so far. It might prevent some infringers and help with branding, but if your images are showing full-size on someone else's search engine than the potential visitor has little incentive to click through.