Horitontal freedom: 20px +/-  |  Verticle freedom: 20px +/- Horitontal step width: 15px +/-  |  Verticle step width: 15px +/-    |START! (Be patient: )
Try auto stroke with different pens many time over the picture. You can change the position of reference picture while drawing.
You can switch reference images when drawing. Press and hold 'E' to move your reference image. Press 'S' to toggle auto/manual color. Undo: Z. Redo: X. Auto stroke: L.