THX tune-up features custom video test patterns, carefully selected photos and tutorials to help you adjust and confirm the best picture settings on your display based on your room lighting.
I recently used this free app to calibrate my television. It pointed out that I had my brightness set too low, resulting in a loss of detail in dark areas. It isn’t perfect – for example, it suggested increasing the colour setting to a point of over-saturation – but it is a helpful starting point.
For those with an Apple TV, the app uses AirPlay to send test patterns and photos to your display. The app also has a set of audio adjustments for testing your 5.1 surround sound system, but that unfortunately requires a digital AV adapter and HDMI cable (I’m guessing AirPlay is limited to stereo signals).