To establish your authorship on photos, the best thing to do is add a watermark. But obviously you don`t want to spoil the beauty of your photos when you do this.
For this, the best thing to do is download a program like PhotoX, which add subtle, discrete and elegant watermarks to each one of your photos. In that watermark you can add the text or image you want (for example your business logo). From PhotoX you can also define the type of text font, the size, put it in bold type, italics, colour, etc.
At no time does it distort the quality of the original photo, letting you work with JPG, BMP, PNG, PNM, RAV, TIFF, WBMP, etc formats. With PhotoX you can also convert those photos to greyscale, and view them as thumbnails.