You may think you're seeing all the color and detail possible on your HDTV, but unless you've adjusted the settings, you may be missing the details.

When your HDTV comes from the factory, most of the video settings – sharpness, brightness, color, contrast, and tint, for example – are cranked up too high. That can result in a picture that looks out of sorts in your living room. Properly set, your HDTV picture should look as close to what you see in the real world as possible.

THX's Tune-up app for iOS reins in your video settings through a series of images that helps reveal your HDTV's true potential.

Calibration tools on DVD and Blu-ray discs have been a staple of the home theater enthusiast for years, but THX's app offers a simple alternative to those, especially if you have tossed out your DVD or Blu-ray player in today's era of streaming media. While the app is free, it requires some some accessories to make it work. If you have an Apple TV, you can use AirPlay to wirelessly display the app's images on your HDTV. Apple's $49 Lightning Digital AV Adapter, which lets you connect your iDevice to your HDTV via HDMI, offers another option.

Once the app is showing on your big screen, Tune-up walks you step-by-step through the process of optimally tweaking your video settings, and it makes it easy to understand. As you display a series of test images and pictures, a narrator tells you what you look for and how to adjust the settings. For example, you verify that your aspect ratio is correctly set, or adjust your brightness to reveal fine details in the dark.

Tune-up makes color and tint adjustments particularly simple. The best way to check if you've got these set properly is to use a red filter to help you, and the app uses the built-in camera to help with this. Point the camera at your HDTV while it displays a test image, and Tune-up superimposes the filter so what you see on your iOS device indicates whether you need to make changes.

The app isn't perfect. Connecting your iPhone or iPad to an HDMI cable can make using the camera for color and tint adjustments unwieldy, so you're better off using AirPlay and Apple TV for this process. And while Tune-up also offers basic tests for adjusting audio, they aren't as useful as the tools that are built in to most current audio-video receivers.

If you already have an Apple TV or Digital AV Adapter, and if streaming media is your primary way to watch movies and TV shows, then this app will come in handy to check that you're getting the best picture possible. But if you lack a way to display the app on your HDTV, or still own a DVD or Blu-ray player, then consider a disc-based calibration tool like DVE HD Basics instead, since it offers additional test screens, audio tweaks, and other options for even more refined adjustments. [$1.99; itunes.apple.com]