I have a number of images on my website with a watermark. We changed the watermark (on all of our images) in May, but when I search for my site getmecooking in Google Image Search, it still shows the old watermark (the old one is grey, the new one is orange). Is Google not updating the images its search results because they are cached in Google? Or because it is ignoring my images, having downloaded them once? Should we be giving our images a version number (at the end of the file name)? Our website cache is set to 7 days, so that's not the issue. Thanks.