LG Electronics 42LP1D LCD HDTV and 42PX4D Plasma HDTV HT Labs Measures: 42PX4D

HT Labs Measures: LG 42PX4D Plasma HDTV

Full-On/Full-Off Contrast Ratio—938:1; ANSI Contrast Ratio—1327:1

Measured Resolution with the Leader LT-446: 480: 480 (per picture height) 720p: 660 (pph) 1080i: out to the limits of the 1024 by 768 panel

DC Restoration (poor, average, good, excellent): Average (poor in daylight picture mode)

Color Decoder (poor, average, good, excellent): Excellent

Measured Color Points:
Red Color Point: x = 0.653, y = 0.337
Green Color Point: x = 0.271, y = 0.658
Blue Color Point: x = 0.149, y = 0.059

The left chart shows the 42PX4D's gray scale relative to its color temperature at various levels of intensity, or brightness (20 IRE is dark gray; 100 IRE is bright white). The gray scale as set by the factory, in the warm color-temperature mode and the movie picture mode, measures warm with the darkest images and gets cooler as the light level increases. After making adjustments using the Photo Research PR-650, the gray scale measures much better, within 189 Kelvin of D6500, the accurate color temperature, across the entire range.

The right chart shows the gray scale (or color temperature) relative to the color points of the display's red, green, and blue phosphors. These are off those specified by SMPTE. Green is very oversaturated and slightly bluish-green, red is slightly over saturated and very slightly reddish-orange. Blue is slightly over saturated and very slightly bluish-purple.

Using a full-field 100-IRE white (25.32 foot-lamberts) and a full-field 0-IRE black (0.027 ft-L), the contrast ratio was 938:1. Using a 16-box checkerboard pattern (ANSI contrast), the contrast ratio was 1327:1. The best contrast ratio was achieved with the power save mode off. The brightest image was achieved with the power save mode off and produced 71.86 ft-L with a 100-IRE window (it is normal for a plasma to have lower light output on a full-field white versus a white window).—GM