This is the only setting I've found in data, cr3.ini (it had been signalled before)
Code:
crengine.image.scaling.zoomin.block.mode=2
crengine.image.scaling.zoomin.block.scale=2
crengine.image.scaling.zoomin.inline.mode=2
crengine.image.scaling.zoomin.inline.scale=2
crengine.image.scaling.zoomout.block.mode=2
crengine.image.scaling.zoomout.block.scale=2
crengine.image.scaling.zoomout.inline.mode=2
crengine.image.scaling.zoomout.inline.scale=2
without any clear understanding of what this "arbitrary scale" provides since some images are displayed full screen, some others take only one third of the screen though they too should be displayed full screen.