Are the DVD and the Apple TV devices connected directly to your Sony TV.
If connected by HDMI cable directly to the TV have these HDMI inputs been set up as Enhanced.
Press Home on the remote control. (the path to this setting maybe different from the one described below as
not all Sony TVs have the same menus.)
Go to System> System Settings> Set Up> Av Set Up> HDMI Signal Set Up, select Enhanced for each HDMI input.
Have you adjusted the picture settings for each HDMI connected device.
It may be that you need to adjust the picture settings for each device differently from the picture settings
you use for watching digital terrestrial TV.
Each input device can have different picture settings from the other.
If the DVD is connected to HDMI 2 for example have you set up the picture setting to suit,
and the same would go for the Apple TV.
The TV remembers the individual picture settings for each device.
Switching between inputs will make the TV switch to the picture settings selected for that input.
Have you checked that any settings on the two devices themselves are set correctly for outputting to the TV.
