Here is the original image
http://3.bp.blogspot.com/-yPKI3PYnpJ4/ToJSOU0FJmI/AAAAAAAAAU4/dn2r-AP8iBs/s1600/shape5.png

Here is what I am able to trace so far











Here is my code so far

1. /*
              |         |
    5(-1,-1)  | 4(0,-1) |3(1,-1)
    ----------------------------
              |         |
    6(-1,0)   |  x      |2(1,0)A
    ----------------------------
    7(-1,1)   | 0(0,1)A |1(1,1)A
              |         |
    */
   PVector [] places = new PVector [8];
   int w = 255;
   int h= 255;
   PImage img;
   PVector now;
   color mark = 0;
   void setup(){
     places [0]= new PVector (0,1,0);
     places [1]= new PVector (1,1,0);
     places [2]= new PVector (1,0,0);
     places [3]= new PVector (1,-1,0);
     places [4]= new PVector (0,-1,0);
     places [5]= new PVector (-1,-1,0);
     places [6]= new PVector (-1,0,0);
     places [7]= new PVector (-1,1,0);
     String fn="http://3.bp.blogspot.com/-yPKI3PYnpJ4/ToJSOU0FJmI/AAAAAAAAAU4/dn2r-AP8iBs/s1600/shape5.png";
   
     img= loadImage(fn);
   
     size(w,h);
     now = new PVector (10,h/2-10,0);
     image(img,0,0);
     mark = img.pixels[0];
   }
   
   
   PVector check(PVector a){
     int x = int(a.x);
     int y = int(a.y);
     int A=0;
     int B = 0;
   
     boolean found = false;
     int _x;
     int _y;
   
     for (int i=0;i<8;i++){
       _x = int(places[i].x);
       _y= int (places[i].y);
       if (img.get(x+_x,y+_y)==mark){
         A=_x;
         found = true;
         B =_y;
   
         i=8;
       }
     }
   
     if(!found)A=1;
     PVector retval = new PVector (a.x+A,a.y+B,0);
     return retval; 
   }
   void draw(){
   
     now = check(now);
     strokeWeight(3);
     stroke(255,0,0);
     point(now.x,now.y);
   }