Judging Picture Quality

Have you ever been disappointed by the poor picture quality of a spanking new TV you just bought, particularly since it looked so brilliant at the store? Here's how to properly evaluate an HDTV at the megastores.

1. The wall of panels

Most electronics stores display their HDTVs on a big wall, fed by the same video signal split a hundred times. Although bright lights, suspect salespeople, and a lack of remote controls will probably make any picture quality judgment difficult, here are a few things to look for on the wall.

Don't fall for brightness: Almost every television on the sales floor is set to the brightest picture settings, so try to get the salesperson to reduce the controls of the TVs you're comparing. You want the pictures--not necessarily the controls--to be roughly equal in brightness, contrast, and color.

Go out of the light: Few living rooms are as well lit as the sales floor, so see if the salesperson can reduce the amount of light shining on the picture. If nothing else, try to shade the screen if light is shining directly on it.

Test materials: If you have a DVD or Blu-ray that you're familiar with, see if you can use it instead of the TV signal that's normally shown. Aside from HDTV, which isn't very portable at the moment, these provide the best pictures that a TV can display, so it makes for a good reference from which to judge.

Try all the picture modes: Many sets come with numerous picture presets such as Movie and Sports, which radically affect how the image appears. After you peruse the manually adjusted pictures, try the different presets and modes to see which ones look best.

2. Features that enhance picture quality

In general, there are a few major factors that affect picture quality. Look for these features or characteristics and disregard others that sound good on the surface but are in reality just marketing ploys. Naturally, there are other important factors we can't cover here, but this should get you started.

Video processor: This is the chip that processes your standard-definition video sources to match the native resolution of your HDTV. Lower-end models tend to introduce video artifacts such as jagged outlines and soft images similar to expolated photos on computers. For the best visual performance, keep a lookout for videophile-grade solutions such as the Faroudja Directional Correlation Deinterlacing. This is normally identified by a DCDi logo in brochures and specifications sheets.

Comb filter: If a television does not have a comb filter, its resolution will be limited to about half the full potential of DVD. Most sets with comb filters can provide all of the resolution of DVD. The types of comb filters you'll see advertised, in order of lower to higher quality, include two-line, three-line, digital, and 3D YC varieties. They provide incremental improvements in performance, especially in reducing rainbows that can appear in fine detail such as a talking head's suit coat. Comb filters affect only composite-video or RF connections (see Inputs and Outputs).

Color temperature settings: Many televisions have presets for color temperature, which is basically the color of gray. A neutral gray is ideal, but most TVs have an extremely blue gray to make the picture brighter in the store. TVs with color temperature presets allow you to choose the color of gray. Generally, you'll want the reddest or lowest setting available.

Color decoder: Most TVs' color decoders are set to be too red to counteract the blue color temperature described above. TV makers don't advertise accurate color decoders, so you'll have to judge for yourself or trust a reviewer. In the store, look for pale skin tones that don't appear too flushed and reds that don't bleed into other colors or otherwise seem more intense than the rest of the palette.

3. Calibration

You'll often see CNET reviews mention calibration or The Imaging Science Foundation (ISF). Our reviewers utilize specialized equipment such as a computerized calibrator to fine-tune the panel for an optimal configuration according to NTSC standards. ISF has a program that trains professionals to calibrate televisions, and for a few hundred dollars, you can engage an ISF professional to adjust your TV.

Alternatively, you can use a calibration DVD to help you adjust your television. These discs, such as Ovation Software's Avia, Joe Kane's Video Essentials, and Sound & Vision's Home Theater Tune-Up, show you how to optimize your set within the limits of the standard user-accessible menus.