Confusing zoom level

I find the zoom level percentage in the current implementation somewhat confusing.

Is 100% supposed to mean _using 100% of the viewport_?

I would find it more intuitiv if the percentage would reflect `screen pixels/image pixels` (in 1D./per axis), i.e., 100% means 1 pixel of the image is mapped to 1 pixel on screen, 200% 1 pixel of the image is mapped to 4 pixels (2 per axis) on screen, etc.