Benq Xl2411Z or Asus VG248QE

[StrobeMaster]

I do know that the LG 24GM77 uses a true 8 bit panel.

Just for the record, the LG-24GM77 sitting on my table has an AUO M240HW01-V8 panel, the same as in other 144Hz 24" monitors (BenQ XL2411Z, Asus VG248QE,...). So it is just 6bit+FRC (see also Panelook).
Nevertheless, the LG-24GM77 uses a different signal processing as compared to the Asus VG248QE and probably also the BenQ. My guess is that LG relies on the dithering done by the panel electronics only, whereas Asus and BenQ do some additional dithering at the scaler level so as to minimize round-off noise caused by the pixel value processing (gamma, contrast scaling, RGB balance, etc.).

[Falkentyne]

I do know that the LG 24GM77 uses a true 8 bit panel.

Just for the record, the LG-24GM77 sitting on my table has an AUO M240HW01-V8 panel, the same as in other 144Hz 24" monitors (BenQ XL2411Z, Asus VG248QE,...). So it is just 6bit+FRC (see also Panelook).
Nevertheless, the LG-24GM77 uses a different signal processing as compared to the Asus VG248QE and probably also the BenQ. My guess is that LG relies on the dithering done by the panel electronics only, whereas Asus and BenQ do some additional dithering at the scaler level so as to minimize round-off noise caused by the pixel value processing (gamma, contrast scaling, RGB balance, etc.).

Oh man.
Strobemaster to the Rescue again...
Everyone was saying this was a TRUE 8 bit panel before...

I don't understand the last part of your sentence though.
Are you saying the LG minimizes round off noise caused by pixel value processing? Or the Asus/Benq do?

How does this affect image quality (especially on very dark or white shades, or shades on top of shades (e.g. transparent fogging / clouds etc?).

[StrobeMaster]

I don't understand the last part of your sentence though.
Are you saying the LG minimizes round off noise caused by pixel value processing? Or the Asus/Benq do?

How does this affect image quality (especially on very dark or white shades, or shades on top of shades (e.g. transparent fogging / clouds etc?).

I was afraid that this question would come up, because it is difficult to explain without getting lost in the terminology. So just look at the attached graph which shows measured luminance (normalized) over pixel value (green channel only) for the LG and the Asus. Note, however, that these measurements average over many pixels, so negative effects of dithering would not show up here, like single-pixel noise (across space and/or time) and interferences between several dithering stages and with pixel inversion. The BenQ and Asus add more of such due to multiple dithering but provide - in a way - more "accurate" colors, which results in less banding. For the LG it is the other way around.
As so often, it is difficult to say which is better. I tend to believe that banding is a big problem at 8bit already, so losing precious color resolution due to multiple rounding, like the LG does, would be a no-go. On the other hand, if you are bothered by the glimmering caused by dithering and pixel inversion, the LG is the better choice. In this respect, BenQ seems to be the worst (IMHO it is horrible), probably due to an unfortunately chosen dithering matrix which interferes more strongly with the panel dithering and/or pixel inversion than in the Asus. Of course, there are other decision criteria, especially for gamers, like input lag, motion blur, overdrive, etc., where I consider the LG being worse than Asus or BenQ.
Disclaimer: Although all these monitors use the same panel, there is panel-to-panel variation. And since part of the dithering is done or can be done at the scaler level, the behavior might also depend on the firmware version.

[Q83Ia7ta]

Just for the record, the LG-24GM77 sitting on my table has an AUO M240HW01-V8 panel, the same as in other 144Hz 24" monitors (BenQ XL2411Z, Asus VG248QE,...). So it is just 6bit+FRC

Thanks for that info. Too bad for LG as lcd panel manufacturer to use lcd panels from another manufacturer. Less rivalry less progress.

[Falkentyne]

Strobemaster,
Since we're on this topic (and I also know you have an XL2730Z), do you know why both the Asus ROG Swift PG278Q and (sometimes) the Benq XL2730Z suffered from excessive inversion artifacts?

Most (but not all TN)'s showed some inversion, usually noticeable on tests on lagom.nl, and some bizarre color patterns of an alternating pixel line color of magneta>white (which is something you would usually never see), but in games you would usually never see inversion.

However the Asus ROG Swift (and apparently the Benq XL2730Z used a very similar 1440p TN panel, although not exactly the same), and some people to a lesser extent, the XL2730Z, would show excessive inversion artifacts in games, when no other monitor would show them. Some examples were in yellow/red muzzle flashes in gun FPS games, around the green character test in World of Warcraft, some examples in scenery in Battlefield 4, and some other cases.

The ROG Swift forum thread on OCN was filled with complaints about inversion artifacts, although not every sample seemed to have them badly. I never saw any type of inversion like this on my XL2720Z, for instance.

One person even noticed horrible inversion artifacts on a Gsync Benq XL2420G monitor, that he never saw on an older XL2411T. He saw it in DOTA2 in spectator mode, when looking at objects shown in the fog of war. It was very distracting for him. I tried that test on my XL2720Z and everything looked normal...

[StrobeMaster]

Strobemaster,
Since we're on this topic (and I also know you have an XL2730Z), do you know why both the Asus ROG Swift PG278Q and (sometimes) the Benq XL2730Z suffered from excessive inversion artifacts? [...]

Not exactly the topic here, but anyway. In my experience, especially with the EIZO Foris FG2421, the strength of pixel inversion can be very sensitive to the monitor settings, like at 50% Contrast it is strong, whereas at 51% it is considerably weaker. Obviously the same is true for the content being rendered. It is still a mystery to me how these artifacts develop - homogeneous color shifts, okay; but lines and patterns??? But what puzzles me most is that pixel inversion artifacts can pop up so strongly out of the blue. I don't know, maybe some resonance effects come into play here, which are triggered by very special and unpredictable circumstances.

[aeliusg]

Strobemaster,
Since we're on this topic (and I also know you have an XL2730Z), do you know why both the Asus ROG Swift PG278Q and (sometimes) the Benq XL2730Z suffered from excessive inversion artifacts? [...]

Not exactly the topic here, but anyway. In my experience, especially with the EIZO Foris FG2421, the strength of pixel inversion can be very sensitive to the monitor settings, like at 50% Contrast it is strong, whereas at 51% it is considerably weaker. Obviously the same is true for the content being rendered. It is still a mystery to me how these artifacts develop - homogeneous color shifts, okay; but lines and patterns??? But what puzzles me most is that pixel inversion artifacts can pop up so strongly out of the blue. I don't know, maybe some resonance effects come into play here, which are triggered by very special and unpredictable circumstances.

From what I gather, it has to do with the "tuning" process (whatever that means at the hardware level) associated with variable refresh rate operation on these panels, specifically the TN ones with aggressive overdrive. Freesync monitors have had similar issues even during what can be considered normal usage unlike with G-sync models that only exhibit these problems under more marginal circumstances. Once again, this seems like a TN issue with G-sync; the IPS and VA displays don't really have this problem: http://www.tftcentral.co.uk/reviews/con ... omparisons

Edit: well, actually you can see some of that here on the Z35 with the VA panel: http://www.tftcentral.co.uk/reviews/con ... omparisons (scroll down to the photo comparisons)

Once again the crux of it seems to be the aggressive overdrive combined with variable refresh rate stuff, whatever is going on.