The Hand Tool controls the current view.
Drag while holding the left mouse button to move the current view.
Use the mouse wheel (or, if the hand tool is selected, drag while holding the right mouse button) to zoom.
The zoom center is the current mouse position. This allows you to zoom in on certain objects. You can even navigate through the image using zoom alone and different zoom centers.
"Zoom" defines how large the image will be shown on screen. If you set "Zoom" to 100%, each image pixel will be mapped to exactly one screen pixel. This can also be done using the "100%" button.
The "Fit" button fits the image into the current view. Zoom is not chosen freely, but rounded to sqrt(2) increments, for better image quality.
At the end of the options bar are 6 alignment buttons.
- Press "C" and "M" to center the image on screen.
- Press "T" to view the top of the image.