by Paul Sanders
One of the issues facing digital televisions is artificial visual artifacts on the screen. Motion blur is a common visual issue, one that has several causes and solutions. To help you better understand motion blur, here are the answers to some frequently asked questions about motion blur and your TV.
What is motion blur?
Motion blur is a visual effect that occurs on many high-definition TVs in which fast-moving objects on the screen appear blurry. This problem is especially noticeable in action scenes and sports programming.
What causes motion blur?
TVs can experience motion blur from several sources, mostly related to how different TVs display picture data and convert video signals to fit the screen.
Response time: LCD TVs change the color of each LCD pixel to create the HDTV picture. The longer it takes each pixel to change from one color to another, the less sharp the picture will be. When TVs play action sequences, the lag time between color changes becomes more noticeable in the form of motion blur. LCD TVs with response times faster than eight milliseconds typically have no noticeable motion blur; any visible blur is likely from another source. Plasma TVs and older CRT TVs have very fast response times, so they don't suffer as much motion blur from that source.
Film-to-video conversion frame rates: Standard movies and TV shows are filmed at 24 frames per second (fps), which needs to be converted to play on TVs that refresh their screens at 60, 120 or 240 Hz. The conversion isn't exactly even, so TVs use image software techniques to insert extra frames, add blank frames or otherwise manipulate the frame rate to fit the refresh rate of digital TVs. The conversion process isn't perfect, and motion blur can be introduced. You can also see "judder," or noticeable jumps, in otherwise smooth camera movements.
Resizing: Most HDTVs use the 16:9 widescreen format to display movies, TV shows and games. If the video source is in a different format, your TV has to adjust the picture to fit the screen. This can introduce slightly different colors and visual artifacts into your TV picture, including motion blur.
How can I prevent motion blur on my TV?
Look for TVs with fast response times and faster refresh rates. Many TVs also include built-in motion blur technology which does a lot to address the problem. You can upgrade to Blu-ray as well. Blu-ray movies are designed for HDTVs, and older films on Blu-ray are often re-mastered to minimize the effects of film-to-video conversion.