The RadImageEditor control provides out of the box zooming functionality. You can zoom in the opened image by holding Ctrl and spinning the mouse wheel or by using the slider and dropdown of the ZoomController provided by the RadImageEditorUI.
Figure 1: Default zoom capabilities
As can be seen in Figure 1, the default zooming mechanism does not take into account the position of the mouse cursor.
As of version 2018.2.716, both RadImageEditor and RadImageEditorUI controls expose a ZoomToCursor property. By setting this property to True, holding Ctrl and spinning the mouse wheel will zoom towards the position of the mouse cursor. The result can be observed in Figure 2.
Figure 2: Zooming to the mouse cursor