Plasma Displays

The gray scale of the Gateway plasma HD monitor, as shown in the top chart and set by the factory in the 6500D mode, measures within 300 Kelvin of 7,000 degrees. The image is much more consistent with brighter images, or those from about 50 to 100 IRE. The gray scale is much closer to 6,500 K with full-field images, which also have half the light output compared with a 15 percent window. After calibration, the gray scale tracks much closer to D6500 K. Again, the scale tracks more evenly above 50 IRE. The bottom chart shows the gray scale relative to the display's plasma phosphor color points. Before calibration, the gray scale is mildly blue, although it doesn't wander too far from the center. After calibration, the set is centered more around the D6500 K point. The phosphor colors are similar to those of other plasmas, which don't quite line up with the color points specified for DTV images. Red (0.623, 0.353) is slightly orange and is probably closer to the NTSC specification. Blue (0.16, 0.106) is mildly cyan. Green (0.265, 0.665) is overly saturated, which will give the image more of a green cast than usual. The peak, undistorted light output is approximately 42 foot-lamberts, measured with a 100-IRE 15 percent window. This drops to 20 ft-L with a 100-IRE full-field image. The color decoder is reasonably accurate, and the display has good DC restoration.—MW