LCDs From Sony, Samsung, Toshiba & Philips HT Labs Measures: Toshiba

HT Labs Measures: Toshiba 52LX177 LCD HDTV

Full-On/Full-Off Contrast Ratio—1,916:1; ANSI Contrast Ratio—980:1

Measured Resolution with the Leader LT-446:
480: 480(per picture height)
720p: 720 (pph)
1080i: 1080 (pph)

DC Restoration (poor, average, good, excellent): Excellent

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

Measured Color Points:
Red Color Point: x=0.644, y=0.324
Green Color Point: x=0.200, y=0.687
Blue Color Point: x=0.149, y=0.068

The top chart shows the 52LX177'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 Preference picture mode, measures too far bluish-green off the black-body curve to get a color temperature with dark images. The rest of the gray scale measures pretty close to accurate, although there is too much green. After making adjustments using the Photo Research PR-650, the low end is still very cool, but there is a more accurate amount of green across the gray scale.

The bottom chart shows the gray scale (or color temperature) relative to the color points of the display's red, green, and blue color filters. These are somewhat off those specified by SMPTE. Red is very slightly oversaturated. Green is very oversaturated and very bluish-green. Blue is very slightly greenish-blue. Some adjustment was possible with the green color point, resulting in x,y coordinates of 0.271, 0.601. This is still rather bluish-green, but it's no longer oversaturated. Test patterns looked odd after this change, while performance with program material was varied.

After calibration, and using a full-field 100-IRE white (21.08 foot-lamberts) and a full-field 0-IRE black (0.011 ft-L), the contrast ratio was 1,916:1. Using a 16-box checkerboard pattern (ANSI contrast), the contrast ratio was 980:1. The best contrast ratio was achieved with the backlight set at 0. The brightest image was achieved with the backlight set at 100. In this mode, the 52LX177 achieved 120.1 ft-L and 0.091 ft-L for a contrast ratio of 1,320:1.—GM