We use a different brand of signature pads, but I'd imagine that process is exactly the same.

You will need to iterate over an array of data points that will likely contain an (x, y) coordinate and some pressure info (or something indicating if the pen was down or not). As you iterate over the points you will want to to use the canvas API to draw lines connecting the previous point to the next point if the next point meets a certain pressure threshold. Once your done you can use the canvas API to generate image data and display that on the form in an <img> 

It might be possible that the Topaz API might have function calls for you to directly retrieve some image data, so I'd start looking there, but if not doing what I described above is simple enough, and you should be able to get it working in a few hours or so.

https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API