This paper presents a method to generate an equivalent on-line signal of a letter image. To do this, an off-line drawing order has to be recovered using handwriting knowledge. Our approach consists in looking for several start and the end points. Then a reconstruction algorithm is applied and finally the best path is chosen. This approach has been validated on a database of handwritten letters including both on-line and off-line signals. An on-line recognition system has been used to recognize these letters.