Grayscale Tracking And Gamma Response
Our grayscale and gamma tests are described in detail here.
Once again we’re comparing Classic and G-Sync modes in the grayscale tests. We’ll also show you the results from the FPS1 picture mode.
In Classic mode, the Standard picture preset comes close to the mark except for 100-percent brightness. That level has a noticeable blue tint. Fortunately, it can be fixed with a few tweaks to the RGB sliders.
Calibration produces an excellent result with just a touch of red in the 90- and 100-percent levels. The error is comfortably below the threshold of visibility however.
FPS1 is one of the dedicated gaming modes. Grayscale tracking is so skewed towards blue that the error goes off our chart at 60 percent and above. In some content, the picture may appear brighter, but color detail definitely suffers for it.
In G-Sync mode, you don’t even need to calibrate for near-perfect grayscale tracking. Just choose the Normal color temp preset. In fact, we tried to improve upon the above chart and were unsuccessful.
Here is our comparison group:
Classic mode measures well out of the box, and G-Sync mode is even better. Our Classic mode results can be improved ever-so-slightly with calibration. But in G-Sync, it’s best to simply select the Normal color temp and be done with it.
Calibrating Classic mode yields the exact same average DeltaE error as G-Sync mode right out of the box. That’s pretty impressive in our opinion. Really though, you don’t need to calibrate either mode for a great image on the XL2420G.
Gamma Response
Gamma doesn’t change much when you calibrate, so we’re showing you the post-adjustment result. It’s pretty solid except for a spike at 90 percent that represents an error of 6.5cd/m2 below the target. At such a high brightness level, you won’t see the problem outright. But it does spoil an otherwise excellent chart.
In the FPS1 gaming mode, tracking is skewed too light at the low end and too dark at the high. Actual content reflects slightly washed-out shadows and highlights that have a little less pop. In effect, the brighter areas of the image have less contrast than they should.
In G-Sync mode, we recommend changing the gamma preset from three to one. It won’t make a difference in Classic mode since the two configurations operate independently.
This gamma result helps explain why we measured lower contrast in G-Sync mode. As the signal level rises, actual output levels don't rise fast enough. The result is a slightly more drab image than the XL2420G is capable of.
Here is our comparison group again:
Classic mode scores lower in this test because of the spike at 90-percent brightness. If it tracked better, the XL2420G would be at or near the top of our comparison group. We know BenQ can do gamma properly given the result posted by its XL2430T. Perhaps a firmware update could fix the errors we encountered.
With a smaller deviation of .32, G-Sync mode tracks a little flatter.
We calculate gamma deviation by expressing the difference from 2.2 as a percentage.
We prefer the gamma in Classic mode given its closer adherence to the 2.2 standard. Remember that we changed the preset from three to one when switching to G-Sync mode. This is the only real weakness in the XL2420G’s video performance.
