It seems Wordpress is doing an exceptionally bad job when it comes to re-sizing my images.
In the media options I have set my image sizes to my liking. Most notably 857px wide for the medium thumbs, and set the quality to 100, as well as turned on sharpening.
I have set the following in the functions.php
add_filter( 'jpeg_quality', create_function( '', 'return 100;' ) );
Sadly this has little to no affect at all on the quality of the images produced in Wordpress.
At first the difference might not appear to be that distinct, but look at the rock? It's probably more apparent on photos with more detail, but it can still be seen here.