![将图像放在表格后面](https://linux22.com/image/418487/%E5%B0%86%E5%9B%BE%E5%83%8F%E6%94%BE%E5%9C%A8%E8%A1%A8%E6%A0%BC%E5%90%8E%E9%9D%A2.png)
答案1
\documentclass{article}
\usepackage{tikz, lmodern}
\usetikzlibrary{calc,tikzmark}
\begin{document}
\begin{tikzpicture}[overlay,remember picture]
\node [yshift=.6ex,rotate=45] at ( $(pic cs:A) !.5! (pic cs:B)$ ){ \fontsize{8}
{6}\selectfont\textbf{\color{black!40}RESTRICTED} };
\end{tikzpicture}
\begin{tabular}{llll}
1 & 2 & 3 & \tikzmark{B}4 \\
1 & 2 & 3 & 4 \\
1 & 2 & 3 & 4 \\
1 & 2 & 3 & 4 \\
\tikzmark{A}1 & 2 & 3 & 4
\end{tabular}
\end{document}