digraph DFA
{
   size = "8 11";

   subgraph cluster0
   {
      label = "header";
      color = blue;
      fontcolor = blue;

      init [label = "x=3", shape = plaintext];
      header_loop [label = "", shape = doublecircle];
      header_newline [label = "x--"];
   }

   subgraph cluster1
   {
      label = "even scanline";
      color = red;
      fontcolor = red;

      even_line_init [label = "flush;x=width-1"];
      even_line_0 [label = "x--"];
      even_line_1 [label = "flush;x--"];
   }

   subgraph cluster2
   {
      label = "odd scanline";
      color = green;
      fontcolor = green;

      odd_line_init [label = "x=width-1"];
      odd_line_0 [label = "x--"];
   }

   // Skip header
   //  P5\n<width> <height>\n<maxval>\n
   init -> header_loop;
   header_loop -> header_loop [label = "?"];
   header_loop -> header_newline [label = "\\n"];
   header_newline -> header_loop [label = "? && x!=0"];
   header_newline -> even_line_init [label = "P && x==0"];

   // Skip odd pixels in even scanline
   even_line_init -> even_line_0 [label = "P && x!=0"];
   even_line_init -> odd_line_init [label = "P && x==0"];
   even_line_0 -> even_line_1 [label = "P && x!=0"];
   even_line_0 -> odd_line_init [label = "P && x==0"];
   even_line_1 -> even_line_0 [label = "P && x!=0"];
   even_line_1 -> odd_line_init [label = "P && x==0"];

   // Skip all pixels in odd scanline
   odd_line_init -> odd_line_0 [label = "P && x!=0"];
   odd_line_init -> even_line_init [label = "P && x==0"];
   odd_line_0 -> odd_line_0 [label = "P && x!=0"];
   odd_line_0 -> even_line_init [label = "P && x==0"];
}