To meet the need of long range real-time monitoring in the opto-electronic measurement of shooting ranges, the image signals collected by a digital camera usually need to be converted into the video signals of Serial Digital Interface (SDI) and overlapped with the corresponding information for displaying. To solve this problem, a Decklink Duo acquiring card is used to convert the video signals in Camera Link Full mode into the dual channel SDI output signals by means of Microsoft Visual Stdio 2010 and OpenCV2.4.11. Then, the output signals are processed by character information overlapping and infrared pseudo-color simulation. In the experiment, the expected displaying effectiveness is achieved. It shows that this method is effective and can meet the requirements of practical tasks.