Panasonic Viera TC-P50GT25 3D Plasma HDTV HT Labs Measures
HT Labs Measures
Full-On/Full-Off Contrast Ratio: 5,060:1
All of the measurements here, unless noted otherwise, were taken in the THX Picture mode, in 2D, through an HDMI input, and with the set adjusted as needed for the most accurate image in a darkened room.
This is the second-best full-on/full-off contrast ratio and black level we have yet measured on any plasma outside of the last generation of the discontinued Pioneer KUROs. Of the currently available plasma designs we’ve tested, only the Panasonic TC-P50VT25 (HT, September 2010) did marginally better (0.004/27.3/6,825:1). In the LCD world, only the best sets with LED backlighting and local dimming have turned in better numbers. The peak-white level shown above can be increased a bit more with the Contrast control without serious consequences, but I judged it suitable for comfortable viewing in a darkened room without deviating from the THX mode’s default setting.
Both the Before Calibration and After Calibration measurements were performed with the THX mode set to Warm 2. The After calibrations were done in the service menu. The THX mode’s color tracking prior to calibration was poor, with a Delta E ranging from 4.3 to 11.5. After calibration, it was 2.4 to 3.5 from 20 IRE to 80 IRE, rising to 5.2 at 100 IRE.
The CIE chart shows the color gamut in the THX mode. The black triangle indicates the Rec. 709 HD standard. While the set lacks a true color management system, it doesn’t need one in THX, where its gamut (the white triangle) is nearly spot on the Rec. 709 HDTV standard.
In the 2D THX mode, the set’s gamma ranged from approximately 2.1 at the low end to 2.3 at the top—a respectable result.
The THX mode becomes the Cinema mode in 3D and cannot be separately calibrated for 3D. Without a separate 3D calibration, the measured Delta E in 3D Cinema (not shown) peaked at 11.3 at 50 IRE. For a 3D calibration, I chose the Custom mode, which offers separate, user-menu White Balance adjustments. The post calibration Color Tracking and the color gamut in this mode (not shown here) were very good to excellent. But the gamma was not, hovering around 1.9 up to 50 IRE and dropping to less than 1.0 at the highest brightness levels. Fortunately, the negative effects of this wildly inaccurate gamma weren’t all that visible on the animated fare that makes up most currently available 3D material. It resulted in a pleasingly bright 3D picture, peaking at nearly 9 foot-lamberts. The 3D Cinema mode had a much more reasonable gamma curve, but also lower subjective brightness together with poor, and noncorrectable, color tracking.—TJN