The final post in the link I gave mentioned adding XM:NOTRPICS to the profile used for your TV in your clients.db file. Have you tried this?
Your server is transcoding the pictures for the TV and resizing them - this entry should stop that happening.
Besides, it was an answer - just not the right one! Only trying to help.
Samsung LE37B650T2WXXU; Liteon 5055GDL+ HDD/DVD Recorder; Playstation 3; Iomega Screenplay HD 500GB; Buffalo Linkstation Pro LS-320GL (running Twonky 6.0.30, SqueezeBox Server 7.6 and acting as a Print Server)