LG OLED65GXPUA OLED Ultra HDTV Review Test Bench

Test Bench

The measurements here were made using CalMAN measurement software from Portrait Displays (www.portrait.com), together with Photo Research PR-650 and Klein K-10A color meters and a Murideo Fresco 6-G pattern generator. The peak white levels given below were rounded to the nearest foot-lambert/nit.


Full-On/Full-Off Contrast Ratio: 154,000:1

In the Filmmaker Mode picture mode with OLED Light at 65, Contrast at 80, and Brightness at 50, the 65GX's post-calibration peak white output was 154 nits (45 foot-Lamberts). The black level could barely be measured, fluctuating between 0.000, 0.001, and 0.002 nits, so I selected 0.001 nits (0.00029 ft-L) as the average for this result.


Pre-Calibration Grayscale

In SDR and Filmmaker Mode, the pre-calibration grayscale Delta E values from 20% to 100% ranged from a low of 1.14 at 20% to a high of 3.56 at 70%. Satisfactory, yes, though not quite up to the best Filmmaker standards. But the most visible deviation from ideal was the peak white level, which in the Filmmaker Mode default values of 25 (OLED light) and 80 (Contrast) measured 23 foot-Lamberts (79 nits), while the standards call for 29 ft-L (100 nits). And even that level (achieved only in the very best theatrical presentations) isn't necessarily ideal for most home viewing. For my SDR calibration I raised the level to 45 ft-L (154 nits) with the OLED Light on 65, and the Contrast still at 80. Post-calibration, the Delta E values ranged from a low of 0.4 at 20% to a high of 2.1 at 100% (no other values were above 1.3).


Post-Calibration Grayscale

The pre-calibration color Delta E values ranged from a high of 3.46 (cyan) to low of 1.28 (red). Post-calibration, the high was 1.42 (cyan) and the low 0.59 (green).

(Delta E is a figure of merit that indicates how closely a display adheres to the color standard. Experts generally agree that at levels below 3-4 the result is visibly indistinguishable from perfect color tracking. Delta E values may be used to characterize the accuracy of either grayscale or color.)

High Dynamic Range (HDR10)

Full-On/Full-Off Contrast Ratio: 123,090:1

In HDR10 Filmmaker Mode with the OLED Light at 100, Contrast at 100, Brightness at 50, Dynamic Contrast Off, and Peak Brightness on High, the peak brightness at 100% was 677 nits and the black level 0.0055 nits for the full-on/full-off contrast ratio shown above. But 100% is well above clipping on the PQ curve (gamma for HDR). A more realistic point just below clipping would be 70%, where the peak white level was 560 nits and the black level the same, for a full-on/full-off contrast ratio of 112,000:1.

The 65GX's HDR10 performance was generally good, with the main oddity being the measured peak white level that rose above the clipping line on the PQ curve as mentioned above. Luminance errors in this region could not be corrected by the multi-point adjustments in the White Balance menu. I therefore did my HDR (and SDR) calibrations only with the 2-point white balance controls.

Before calibration, the grayscale Delta Es ranged from a low of 1.9 at 20% to a high of 12.9 at 90%. At 60% and below it was 4.2 or less. Note that the 12.9 value reflects the uncorrectable luminance deviation from the PQ curve (clipping above about 70%). After calibration, the maximum Color Delta E was 2.4 at or under 60%. The errors above 60% were entirely in luminance and are not reflected in white balance charts shown here which do not include luminance.

The HDR peak white levels with varying-sized 100% luminance windows measured 550 nits at 5%, 650 at 10%, 250 at 50%, and 130 at 100%. The 65GX measured 74.7% of BT.2020 and 97.8% of the P3 color gamut using the 1976 standard. (No consumer source material as yet exceeds P3.)

I measured a 1080p image lag of 13ms in Game mode, increasing to just over 84ms in Filmmaker mode (Instant Game Response engaged for both).

The 65GX passed all of our standard video tests. The set will also pass Dolby Digital 5.1 soundtracks from its optical digital audio output, but only 2.1 with a DTS source.

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