I think the images presented in the browser and PDF offered up from the "PDF issue" link have different methodologies.
The TROVE newspaper images in the browser are JPEG 'tiles', each 256 x 256 pixels and approx 7 to 20 kb each - depending on the zoom setting. Can't notice any real difference between a screen print at 100% zoom compared to a downloaded JPEG or PDF at 100% zoom.
The images in the Google News Archive are also 256 x 256 pixel JPEG tiles.
The online Football Records are all PDF's that appear in a custom PDF viewer - some of which seem to have been scanned at too high a resolution.