What resolution are you talking about when you say high definition? 1080p or 4K? What app are you using for playback? Kodi / HiMedia Media Center / Kodi+wrapper?
First 10 Pro system resolution could be wrong. For a full-HD TV Home - Settings - Display should almost certainly be set to 1080p 60Hz.
If you're playing using Media Center or Kodi+wrapper press menu on remote during playback. Now navigate to Advanced Options - PQ Settings. You could try experimenting with these settings to get best picture but personally I would have everything off with minimum processing. So:
Display Mode - Standard.
Imprex Engine - Off (default is On)
The Imprex options are the most important for picture quality. To turn them off as completely as possible:

Finally, you could try switching colour space mode. Go Home - Settings - More - Advanced options - Video color space & HDMI deep color. Switch between the RGB444 8bit, YCbCr444 8bit and YCbCR422 options to see which looks best.