Vizio E550i-B2 LED/LCD HDTV Test Bench

Test Bench

Full-On/Full-Off Contrast Ratio: Unmeasurable

With a 100% peak white window level of 29.95 foot-lamberts, and the Active LED Zones (local dimming) engaged, the full-screen black level of the set, and therefore the full-on/full-off contrast ratio, was unmeasurable. When I engaged the pause bug on the Blu-ray player (which places a small pause symbol on the upper left-hand corner of the screen, while the rest of the image remains full black), the center screen black level increased to 0.0008 ft-L, for a full-on/full-off contrast ratio of 37,437:1.


With the Contrast control turned up to 84 (allowing for 3% peak white headroom), the Backlight on maximum, and the Black Detail control on High, and with the other controls remaining as calibrated, the peak white level was 64 ft-L—lower than on many pricier LCD sets but more than adequate for any practical viewing situation.

Delta E is a figure of merit indicating how close the color comes to the D65 HD color standard. Values below 3 are generally considered visually indistinguishable from ideal, and under 10.0 likely to be acceptable to the average (non-critical) viewer. Pre-calibration (in the Calibrated Dark Picture Mode, but with the Backlight on 60, the Brightness 53, Contrast 75, Color 50, Tint –6, Active LED Zones engaged, Color Temperature Normal, and Black Detail Medium), the set’s gray-scale Delta E averaged 5.57, peaking at 7.82 at 100% brightness. The pre-calibration color Delta E averaged 9.41, with blue the biggest offender at 15.11. Nevertheless, the pre-calibration color of our sample, judged by eye, was respectable. Post-calibration, the average gray-scale Delta E dropped to 2.0, with a maximum of 3.45 at 100% brightness and no value higher than 2.41 at 80% or below. The post-calibration color Delta E averaged 1.82 with blue, as before, the highest at 5.93, and no other color above 1.8.


Post-calibration, with Active LED Zones (local dimming) on, the set’s gamma averaged 2.09, with a low of 1.67 at 20% and a high of 2.31 at 90%. Turning the Active LED Zones off changed the average gamma to 2.21, with a low of 2.03 at 20% and a high of 2.27 at 50%.—TJN

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