That should be doing a pretty good job. I mean, can you do better? Yes, a nice AMD or Nvidia card doing post-processing can look better. But by default that should look pretty good with the right software.
is this a gpu power recommendation? (as it needs more power for software post processing)
or
is this a gpu hardware recommendation? (as a dedicated gpu is simple better than igpu by design)
same as OP.
mkv video are a little grainy (windows media player + k-lite codec via HDMI).