Panasonic TH-58PZ750U Plasma HDTV HT Labs Measures

HT Labs Measures: Panasonic TH-58PZ750U Plasma HDTV

Contrast Ratio: Full-On/Full Off 1,905:1

The top chart shows the Panasonic’s color primaries and secondaries (colored circles and white triangle) plotted on a 1931 CIE chromaticity chart overlaid against the SMPTE-specified standards (colored diamonds and gray triangle). While the red and blue color points are reasonably close to the correct values, green is slightly oversaturated. The Panasonic’s color decoder performed well but with a little too much red push, which is a common error.

These charts show the pre- and post-calibration color temperature/gray-scale tracking. The more tightly the three colors overlap, the closer the result is to the D65 standard. (A color temperature of 6500K is actually a line on the CIE color chart. D65 is the actual point on that line that defines the standard.) The post-calibration result does drift toward blue above about 80 IRE, but it adheres much more closely to the D65 standard overall.

With a 1080i, HDMI input, the aspect ratio set to Full, and the HD size control at Size 2 (no overscan), the sharpness test pattern was virtually flawless, with a crisply defined one-pixel-width line. The luminance burst at the HD maximum 37.1 megahertz was beyond criticism, and the color burst was very nearly as good. This is indicative of excellent resolution at the highest HD frequencies.

At 720p HDMI, in Full, there was dramatic rolloff visible at the maximum frequency of both the luma and color bursts. The overscan in 720p is fixed at 2.5 percent on each side of the image, which is the likely culprit here. (Overscan, which reduces resolution, is 0 percent in the Size 2 setting of the HD size control, but that option is available only in 1080i/p.

The component resolution was nearly identical to HDMI. A trace of noise was visible at the top burst frequency in 1080i, but this is unlikely to be an issue in normal viewing.

The 1,905:1 peak contrast ratio referenced above was captured with the Panel Brightness at its Mid setting, using a 100-IRE white-window pattern versus full-field black. Increasing the Panel Brightness to High increased the light output to 41.6 foot-lamberts without raising the black levels for a slightly higher contrast ratio. But the Mid setting was more comfortable for viewing in a darkened room, and that’s how the set was watched for the bulk of its review.—TJN

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