When opening a map, OKMap by default opens the image on quite a small scale (not sure exactly what scale, but considerably less than 100%).
My personal preference would be to have the map image open by default at 100%. I realise that not everyone would want this, so I was wondering if it is possible to have an option in "Preferences" to open images at 100% by default?
It's only for the first time you load a map (the small map). Then, I think may be useful to locate the place of the last time. If you prefer to load a map at 100% zoom you can press Zoom 100% before close your map.
If you want to rescale an image with OkMap, you can use the function Utilities - Map tiling - Resize (page). This automatically creates a new georeference file (.okm), so you don't need to re-calibrate map.