When loading the file https://www.nasa.gov/specials/blackmarble/media/BlackMarble20161km.jpg with gwenview 16.04.3 (Kubuntu 16.10) the file will show (after a few seconds) fitted to the current window size. When clicking on "100%" the display-area will go white and only show a message, that the loading of the image failed (German message: Das Laden der Datei "BlackMarble20161km.jpg" ist fehlgeschlagen. Laden des Bildes fehlgeschlagen). I kind of expected problems (the image is 43200x21600 pixel) but... well, I thought my machine should be able to handle files of this size. :)
Gwenview is limited to 32760x16384 pixels (2 gigabytes) by Qt's architecture. For larger images, please use specialized software.