The Zoom feature lets you magnify or reduce your view of the image.
In the Properties Area of the Video Effect window you can change the effect properties. The properties of the Zoom effect available for setting are magnitude of zoom as well as shifts along the X- and Y-axes.
Specifying a negative value for the Zoom parameter the entire video picture will be zoomed out, a positive value will zoom it in.
As for Center X and Y parameters the mathematical principle is the same as for X and Y coordinate axes. Depending on the value set for the Center X and Center Y the video picture will be shifted to the appropriate quarter of the preview area leaving the rest of it black.
On the figures below you can see the video picture before and after applying the Zoom effect:
Before applying the Zoom effect
After applying the Zoom effect