I have this issue with an older 36" TV/CRT. If you have an nvidia card, there is hope. From the kde desktop, launch a terminal, become root
Then from the terminal window run nvidia-settings
There is an option in the window presented for "X Server Color Correction" Select it and adjust Gamma, Contrast, and Brightness to about 3 or 4. Then exit the application. This will have created a file in roots home directory /root/ called
To get this to stick (and after you play around until you get the right picture quality) add the following line to /usr/pluto/bin/lmce_launch_manager.sh
This will apply your changes every time the launch manager is started.
Hope this helps.