Webdesign: What is a royalty-free image?
Contrary to what one might think, “royalty-free” images (or photographs, etc.) are not really free to use and/or modify.
They are always subject to copyright (Code de la propriété intellectuelle – Article L111-1) but also governed by a specific license of use.
The creator can indeed decide to place his work under a free license, that is to say that he gives free and prior permission to everyone to use his work under the conditions provided by the license. Creative Commons and Art Libre are examples of free licenses.
If an image is placed under a free license, you can use it (according to the terms of the license) without having to ask the author’s permission.