Control image:  Click image to stop rotation. Drag it to pan right, left, up or down!

Zoom:  If gray bar with + & - appears below image, Click on its + (in) and - (out) buttons.

Alternate Zoom:  If NO gray bar with + & - appears below image, then 

                      1. Click image, Release mouse button, then on keyboard

                      2. Press & Hold Shift button to zoom in, or Control button to zoom out,  

                    while Clicking image to activate zoom.