Image zooming loses reflections/twinkles

[ndevenish]

To discuss together later. Basically, dials.image_viewer properly shows pixels that are smaller than visible

[dagewa]

This was discussed at the DUI meeting, 18 July 2019. The conclusion was that this is something it is important to get right, but may involve a reasonable amount of work. Synchweb does not do it right - leading to anecdotal advice to "not use the Synchweb image viewer". Hence the importance.