How to Put a Watermark on Your Photos
But how you put a watermark on your photos is important for search results. John Harrington has a great blog post on search engine optimization for your images. He quotes Grover Sanschagrin: "Search engine providers have told us that heavily watermarked images provide a 'poor user experience,' and they receive a lower search ranking or are not included in search results at all."
So put a watermark on your photo and do it right for the best results.