To maintain a display standard across our review units, we calibrated the Panasonic VIERA VT20S with the Spyder3TV Home Theater Color Calibration kit prior to our visual tests. This is to ensure we assess the HDTV based on optimal display settings, and not purely on visual estimation alone. At this point, we've also disabled all the necessary bells and whistles such as color and edge enhancement features. After the calibration process, optimized values were as recorded as such: Brightness at 38, Contrast at 85 and Color at 51. Black and white luminance readings were measured as 0.020 cd/m2 and 130.224 cd/m2 respectively. Judging from the calibrated values, little changes need to made to the panel's Color, Contrast and Tint since they were already pre-tuned close to the sweet spots. On the other hand, Spyder3TV thinks the default Brightness value needs to be brought down a notch. Interestingly, the VIERA scored very similar black luminance values as LG's LX9500, which carries an LED-backlit LCD panel if you recall. White luminance readings were significantly less intense at 130.224 cd/m2, when pitted against the brighter LX9500 with a value of 203.497 cd/m2. For that matter, Panasonic is touting a Dynamic Contrast Ratio of 5,000,000:1 off its spec sheet.
DisplayMate is an application which generates a sequence of test patterns to determine the capabilities of imaging devices like color and gray-scale accuracies for example. For our tests, we've hooked up the VIERA VT20S to our display test-bed PC via its HDMI connection. To be fair across the board, we have also disabled all visual enhancements on the TV in order to reduce the variables involved. Here are some findings based on the relevant and critical test patterns:-
Predictably, the VT20S served up better screen uniformity compared to general LCD candidates. Uneven backlight bleeds were non-existent since we are dealing with a plasma panel. These findings were ascertained on both white and black test patterns. One concern we have, however, is the unmistakable presence of digital noise.
Dark Gray Scale
Gray scale reproduction was almost pitch perfect with the VIERA. If we may add, blacks were also satisfyingly deep and dark, with thanks to Panasonic's new fangled Infinite Black Pro perk. LED-backlit screens may come close to black-level perfection, but all it really takes is a decent plasma to remind you otherwise. One trade off is we had to bump up the brightness in order to discern the darker gray blocks. In a few words; awesome blacks with excellent gray scale accuracy.
Gradients were even and gradual on the color bars, except for the lighter blue strip which darkened a shade too quickly. Color performance was on track, although we had to pull down the contrast levels (as shown on our Spyder3TV report) to reduce the TV's overcompensated visuals. Whites were also visibly more pristine after tuning its colors and tint.
256-Intensity Level Color Ramp
Darkening gradients diminished at slightly different rates across the four color bands, more so on the blue strip. Apart from that, the plasma display exhibited little signs of unnatural compressions. Viewing angles, as anticipated, were excellent.
IDT's HQV Tests are designed to assess image quality and the handling of digital displays and players through a variety of video signal processing tasks which includes decoding, de-interlacing, motion correction, noise reduction and film cadence detection. We've programmed the Blu-ray player to playback in 1080i in order to stress the TV's video processor. This compels the TV's processor to convert interlaced signals into progressive to accommodate the HDTV's panel. Here are the results we noted on a few of the most crucial tests:-
Digital Noise Filtering
The VIERA VT20S has four levels for its noise reduction algorithms; Off, Min, Mid and Max. The good news is, they did little to affect picture detail at best. Bad news is, they also did little to remove video noise present.
Diagonal Filter Test
The rotating bars were almost "jaggy" free, which demonstrated the VIERA's video reconstruction finesse. Samsung's C8000 impressed us with its diagonal filtering performance, but we have to admit the VT20S is closer to de-interlacing perfection.
Film Resolution Loss Test
Unfortunately, the VT20S wasn't very comfy in dealing with the inverse telecine process or the reproduction of 24p video. Besides a lack of native film cadence detection, we couldn't locate any feature on the TV to apply the appropriate inverse cadence on the test pattern.