Papers are often used to refer to articles that conduct research in various academic fields and describe academic research results, so they are called papers. It is not only a means to discuss problems in academic research, but also a tool to describe academic research results in academic exchanges. Its nature determines it, so it is a very representative article. The author now wants to add his own DIY watermark to the picture to tell you that his own picture is ok. That will also effectively protect your rights and interests. If you use other people's pictures, you need to get the author's consent. (Note: Because you have to add your own watermark. ) If it is a network picture, not the kind of the last author, it can be extracted by netizens.