diff --git a/img/.gitignore b/img/.gitignore
new file mode 100644
index 0000000..9d73a93
--- /dev/null
+++ b/img/.gitignore
@@ -0,0 +1,2 @@
+*.eps
+*.ps
diff --git a/img/Makefile b/img/Makefile
new file mode 100644
index 0000000..359657e
--- /dev/null
+++ b/img/Makefile
@@ -0,0 +1,10 @@
+SRC=$(wildcard *.dot)
+OUT=$(SRC:.dot=.png)
+
+%.png : %.dot
+	dot -Tpng -Gdpi=300 $< -o $@
+
+all: $(OUT)
+
+clean:
+	rm -f $(OUT)
diff --git a/img/errors.png b/img/errors.png
deleted file mode 100644
index 748f683..0000000
Binary files a/img/errors.png and /dev/null differ
diff --git a/img/fork.png b/img/fork.png
deleted file mode 100644
index 10c08f4..0000000
Binary files a/img/fork.png and /dev/null differ
diff --git a/img/hm.png b/img/hm.png
deleted file mode 100644
index f9af0ea..0000000
Binary files a/img/hm.png and /dev/null differ
diff --git a/img/matrix.png b/img/matrix.png
deleted file mode 100644
index 1a62273..0000000
Binary files a/img/matrix.png and /dev/null differ
diff --git a/tutorial.md b/tutorial.md
index ca37480..6ab92bb 100644
--- a/tutorial.md
+++ b/tutorial.md
@@ -4858,9 +4858,7 @@ associated with their methods.
 * `Foldable`
 * `Traversable`
 
-<div class="center">
-![](img/class.png)
-</div>
+![](img/class.png){ width=250px }
 
 Instance Search
 ---------------
@@ -9741,7 +9739,9 @@ class Fractional a => Floating a
 class (RealFrac a, Floating a) => RealFloat a
 ```
 
-![](img/numerics.png)
+<center>
+![](img/numerics.png){ width=250px }
+</center>
 
 Conversions between concrete numeric types ( from : left column, to : top row )
 is accomplished with several generic functions.
@@ -10198,7 +10198,7 @@ definition graph.
 
 So for example we can construct a simple graph:
 
-![](img/graph1.png)
+![](img/graph1.png){ width=100px }
 
 ```haskell
 ex1 :: [(String, String, [String])]
@@ -10220,7 +10220,7 @@ sc1 = scc' (fromList ex1)
 
 Or with two strongly connected subgraphs:
 
-![](img/graph2.png)
+![](img/graph2.png){ width=250px }
 
 ```haskell
 ex2 :: [(String, String, [String])]
@@ -10281,7 +10281,7 @@ x = G.insEdges edges gr
   nodes = zip [0,1 ..] [2,3,4,1]
 ```
 
-![](img/graphviz.png)
+![](img/graphviz.png){ width=100px }
 
 DList
 -----
@@ -10732,7 +10732,7 @@ fork :: Par () -> Par ()
 spawn :: NFData a => Par a -> Par (IVar a)
 ```
 
-![](img/par.png)
+![](img/par.png){ width=250px }
 
 ~~~~ {.haskell include="src/22-concurrency/par.hs"}
 ~~~~