Vous Il suffit d'utiliser `\offinterlineskip`. Sinon vous pouvez modifier localement le paramètre `\lineskip`.
\documentclass{article}
\usepackage{graphicx}
\begin{document}
Bla bla
{\setlength{\lineskip}{0pt}
\includegraphics[width=.5\textwidth]{example-image-a}%
\includegraphics[width=.5\textwidth]{example-image-a}
\includegraphics[width=.5\textwidth]{example-image-a}%
\par}
Foo bar
{\offinterlineskip
\includegraphics[width=.5\textwidth]{example-image-a}%
\includegraphics[width=.5\textwidth]{example-image-a}
\includegraphics[width=.5\textwidth]{example-image-a}%
\par}
\end{document}
