diff --git a/content/04.summary.tex b/content/04.summary.tex
index c8ba7bd..3f0e028 100644
--- a/content/04.summary.tex
+++ b/content/04.summary.tex
@@ -129,7 +129,7 @@ \section{总结}
       \end{itemize}
     \end{column}
     \begin{column}{.45\textwidth}
-      \includegraphics[width=\textwidth]{TFZsuperellipse-crop.pdf}
+      \includegraphics[width=\textwidth]{TFZsuperellipse-crop.png}
     \end{column}
   \end{columns}
 \end{frame}
diff --git a/fig/TFZsuperellipse-crop.pdf b/fig/TFZsuperellipse-crop.pdf
deleted file mode 100644
index 890492b..0000000
Binary files a/fig/TFZsuperellipse-crop.pdf and /dev/null differ
diff --git a/fig/TFZsuperellipse-crop.png b/fig/TFZsuperellipse-crop.png
new file mode 100644
index 0000000..d747073
Binary files /dev/null and b/fig/TFZsuperellipse-crop.png differ