Now add measurement points to the frames by hovering the arrow cursor over the point and doing a
Ctrl-Click. If you have checked Autostep above, it should automatically step to the next frame when a
mark is added. Again, you can zoom in to get more precise placement. One nice thing about the
zoomed placement is that the precision is better than a pixel. You get access to the zoomed pixel scale.
This is useful if, as is usually the case, edges are not sharp. You can interpret the relative gray of the
edge pixels to get a consistent positioning.