diff --git a/doc/include/ascending.png b/doc/include/ascending.png
deleted file mode 100644
index c82b76ff..00000000
Binary files a/doc/include/ascending.png and /dev/null differ
diff --git a/doc/include/blank.png b/doc/include/blank.png
deleted file mode 100644
index cee9cd37..00000000
Binary files a/doc/include/blank.png and /dev/null differ
diff --git a/doc/include/descending.png b/doc/include/descending.png
deleted file mode 100644
index 4accf927..00000000
Binary files a/doc/include/descending.png and /dev/null differ