It seems that there was a change in the quality of article and banner images after the 2016.8 release. They are all display at a low ppi. The same article images have been uploaded at a minimum of 2000px wide, and look perfect on a retina iPad. But the Web viewer looks horrible. Same problem in 3 different apps I've worked on for 3 different companies. Was there a recent change in how article images are automatically downsampled for the Web Viewer?
For an example, see this app:
(This is just an app I use for testing and training and trying new things, not a "real" company or app!)
There was a change because the web viewer was downloading potentially huge images, which led to very slow loading experiences. I've passed your post on to the dev team to take a look.