Results: Viewing Angles and Uniformity
Besides greater contrast, plasma technology's other big advantage over LCD is superior off-axis image quality. If you plan to put more than three people in front of your HDTV, a plasma panel ensures that even those seated furthest from the sweet spot still see a great picture.
There is no visible difference between the head-on photo and the 45-degree one. Light output, detail levels, and color are unaffected when you sit off-center.
The top-down view is another matter entirely. Looking at the screen from a 45-degree angle above-center, the image is almost completely invisible. This behavior is not typical of other plasma displays. When we asked Samsung about it, representatives told us the F8500 has an additional polarizing layer added to help reject light reflected from the ceiling. Fortunately, side-to-side quality isn't affected, and at normal viewing distances the extra layer doesn't pose a problem. Just use common sense when you're installing the TV so the screen’s centerline is either at eye level or directed that way.
Screen Uniformity: Luminance
To measure screen uniformity, zero and 100-percent full-field patterns are used, and nine points are sampled. First, we establish a baseline measurement at the center of each screen. Then the surrounding eight points are measured. Their values get expressed as a percentage of the baseline, either above or below. This number is averaged.
It is important to remember that we only test the review sample each vendor sends us. Other examples of the same TV can measure differently.
First up is black field uniformity.
As size increases, manufacturing perfectly uniform screens becomes more difficult. LCD technology is at a disadvantage because its backlight is on the edges, requiring equalization with carefully placed diffusors. Plasma should fare better since its pixels emit their own light.
With that said, Toshiba should be proud that its 65-inch screen bests a 51-inch plasma in our test. Still, the F8500’s score of 13.96 percent isn’t too bad. Our measurements show slight hotspots in the upper-left and middle-right zones.
Here’s the white field measurement:
Plasma clearly wins in the white field test. Our reference Pioneer is still king. Samsung isn’t far behind. And we’re not surprised to see LG's computer monitor sneak into third place. NEC’s V801 finishes in a distant sixth place, mainly due to its 80-inch screen size. That’s a lot of area for an edge-backlight to cover.
Screen Uniformity: Color
To measure color uniformity, we display an 80-percent white field and measure the Delta E error of the same nine points on the screen. Then we simply subtract the lowest value from the highest to arrive at the result. A smaller number means a display is more uniform. Any value below three means a variation that is invisible to the naked eye.
Color uniformity is equally affected by screen size, so we wouldn't necessarily expect Samsung to run away with first place. Most 24- and 27-inch computer monitors measure under two Delta E. For the F8500 to demonstrate the same strong performance is a pleasant surprise.