Somewhat related, but back in the old days (maybe better to say early days) we used a different technique although purely for fun. Yes, you can clip an image,

Somewhat related, but back in the old days (maybe better to say early days) we used a different technique although purely for fun. Yes, you can clip an image, but you can also scale an image, making it half the size of the original. The fun-part is that Netscape Navigator would render all the even lines, and Internet Explorer rendered the uneven lines (or the other way around). Making the picture vendor-specific :-) Since almost all the current browsers use the same render-engine (and if not probably the library) you can make you image bigger and hide some watermark in the non-rendered pixels.