Vizio M658-G1 M-Series Quantum LCD Ultra HDTV Review Test Bench

Test Bench

The measurements here were made using CalMAN measurement software from Portrait Displays/Spectracal, together with Photo Research PR-650 and Klein K-10A color meters and a Fresco Six-G test pattern generator from Murideo/AVPro.



Full-On/Full-Off Contrast Ratio: 34,400:1

In the Calibrated Dark Picture Mode, the SDR settings were configured to produce a peak white level of 172 nits and a black level of 0.005 nits, resulting in the above value for full-on/full-off contrast. In both SDR and HDR, local dimming in the Medium setting used here did not fully blacken the image with a solid black test pattern, but it was very dim and invisible in all but a totally dark room.

In Normal Color Temperature setting at this brightness level, the pre-calibration grayscale Delta E from 20% to 70% was a maximum of 2.6. It rose gradually to 4.4 at 100%. Post-calibration using only the 2-point White Balance controls, the maximum Delta E was 2.7 at 50%. The maximum color gamut Delta E was 1.88 (yellow) before calibration (no CMS controls were used for the SDR calibration). With the 2.2 Gamma control setting selected, the Gamma ranged from 2.28 at 20% brightness to 2.38 at 70%.

(Delta E is a figure of merit indicating how close the color comes to the D65 HD standard at each point in the brightness range. Values below 3—some experts allow for 4—are generally considered visually indistinguishable from ideal.)

Full On/Full Off Contrast Ratio: 109,175:1

With a 10% white window, in the Calibrated Dark Picture Mode and the settings shown in the on-line version of this review (similar but not identical to the default settings for that mode) the measured peak white level was 436.7 nits and the black level 0.004 nits for the measured full on/full off contrast ratio shown above. With HDR the brightness range below 50% is intended to encompass all program material of normal brightness, however, with the range from 50% to 100% reserved for the bright highlights that distinguish HDR from SDR. The post-calibration brightness of the M-Series Quantum measured 72.7 nits at 50% and the black level 0.004 nits, for an effective HDR10 full-on, full-off contrast ratio, not including the effect of bright highlights, of 18,175:1.

The Vizio's PQ curve doesn't follow the PQ standard as closely as some TVs I've measured, but the match was satisfactory. (The HDR PQ curve defines how the output luminance varies with increasing source level and is functionally similar to, but effectively different from, gamma for SDR.) The target for 50% luminance on the HDR PQ curve, which is in theory fixed and not variable, is 94.4 nits. While the 50% value shown above may appear to be well short of that, the 94.4 nit level was reached at about 53% brightness in the settings used here.

The pre-calibration white balance Delta Es of the Vizio reached a maximum of 7.8 at 65%, but much of this high value is due to luminance errors being included in the Delta E computation (performed automatically in the CalMAN program). Post calibration the values were roughly the same, but when we exclude luminance (to which the eye is less sensitive) the Delta Es never exceeded 1.9. Before calibration, the color gamut Delta Es reached a maximum of 5.5 in yellow, but post calibration using the set's color management system never exceeded 2.32.

HDR luminance measured 220 nits on a 2% white window, 440 nits on a 10% window, 435 nits on a 25% window, and 320 nits on a full 100% white window.

Color saturation tracking was fair to good in the Rec. 2020 color gamut, good in P3 within Rec. 2020, and also good in Rec.709 within Rec. 2020. The Vizio achieved 79.7% of Rec. 2020 and 98.1% of P3 (1976 standard).

The Vizio passed all but one of our standard video tests (upconversion from 1080i to 4K) with no reservations. The 3:2 HD test was borderline, failing only because it couldn't match the processing of an Oppo UDP-203 Ultra HD Blu-ray player.—TJN