After opening the basic picture the logo is shown. In contributed pictures the label with the name and institution of the contributor is shown as well. The logo and label disappear after a while, so that the quality of the picture is not affected.
The logo, shown in upper left of each text page of the atlas is a place, where a tiny iconized preview of each picture is shown as a response to putting the mouse over the picture name. Clicking the mouse on the logo will get you back to the page with contents.