How We Test HDTVs

PC World's testing philosophy has always been--and continues to be--to evaluate technology products in a real-world setting, with applications that an average user is apt to use day in and day out. We test the image quality of HDTVs by using a jury of PC World editors, freelance or staff writers, and PC World Test Center analysts. The testing methodology we use was developed by and is the property of the PC World Test Center.

Test Environment

All HDTVs must support DVI-V or HDMI for digital video streams. If an HDTV has both, we use DVI-V. We do not test HDTVs that have neither.

In Video: How We Test High-Definition TVs

We test under two different lighting configurations. The standard test suite is performed under 5000K lighting (one bulb per bank). The bright-light test is performed under banks of mixed bulbs (two 6500K bulbs and one 5000K bulb).

We place the HDTVs on long tables, with the midpoint roughly at eye-level for someone sitting in a chair. HDTV vendors have said they design their sets so that the viewers' eyes will be at the midpoint when the set is placed on the ground and the viewers are seated.

We use a color analyzer to choose the preset color temperature setting that most closely matches the recommended setting of 6500K. We then conduct a consumer level-calibration using "AVIA: Guide to Home Theater and Digital Video Essentials." We adjust all available end-user accessible controls, following the instructions on the discs. The resulting calibration will be better than one performed by an end-user--our target reader--but not as precise as one done by a professional.

Content for the jury tests was recorded from various local off-air (antenna) sources using a MyHD PCI card with a DVI-HD daughtercard on a PC test bed. The content is played from the PC through a DVI distribution amplifier to the HDTVs.

To ensure consistency across test batches, we include a previously tested baseline HDTV of the same size as the new HDTVs in each test batch.

The Main Group of Tests

We view various types of content on each TV and rate each clip from 1 to 7 according to various attributes. The majority of the testing is performed in dim lighting with just the 5000K bank of lights on.

HD loop: This loop contains typical content originally recorded in native HD format and broadcast on HD channels.

• Two Men With Cars (IND-KRON--1080i): This clip has some well-saturated red cars in the background. One of the men wears a solid green shirt that shows some pixellation/blotchiness on some sets.
• Two Talking Heads (PBS-KQED--1080i): This is a simple clip with close-up shots of two men in suits talking. We look at the skin tones under controlled studio lighting and the details in the hair and faces.
• "Joan of Arcadia" (CBS-KPIX--1080i): The scenes in this show are shot intentionally dark. We use this clip to look for details in the dark areas and to judge overall brightness and contrast.
• "The George Lopez Show" (ABC-KGO--720p): This is a typical half-hour sitcom with bright studio lighting and many colors, skin tones, and textures.
• Train (PBS-KQED--1080i): This clip has a few long outdoor shots with slow-moving trains and stationary backgrounds of trees, grass, sky, and so on.

SD loop: Much of the content on HD channels is still originally recorded in standard-definition format. This loop is a small sample of such content.

• Baseball (Fox-KTVU--720p): This is a clip from a typical baseball game. Since it is upsampled for broadcast, there is some blockiness/pixellation. Some sets make this effect look worse than others TVs do.
• "Hollywood Squares" (CBS-KPIX--1080i): This clip contains more standard content on the HD channel. It includes a variety of colors and skin tones.

DVD scenes: A major reason that people are buying wide-screen TVs is to watch DVDs. We evaluated a scene from each of two different DVDs.

• "Seabiscuit" (Chapter 25): This DVD, and this scene in particular, is regarded in the industry as very high quality and very well-mastered. It offers many colors and textures, as well as motion sequences, to evaluate.
• "The Lord of the Rings: The Return of the King" (Chapter 22): This high-quality DVD has good detail in some very dark areas.

Bright-light test: For this test, we turn on both banks of lights to simulate a bright, mixed-lighting situation that people may encounter when watching TV in the daytime, when many different lights are turned on. This kind of lighting can affect a TV viewer's perception of brightness and contrast. For this test, we evaluated three clips together and rated overall brightness and contrast, vividness of color, and overall picture quality. The clips are Baseball, "Joan of Arcadia," and "The George Lopez Show."