Showing posts from February, 2021

AOC Envision G19LWK review: input lag and upscaling tested using the piLagTesterPRO

This TN 1440x900 LCD sold thru 2008.  But as it turns out it has very low lag and pretty good response time, showing that display technology has not advanced anything like CPUs or GPUs over the same timespan.  

Overview/Image quality

At native resolution viewed from straight on this LCD looks fine. Because it's a TN display viewing angles are poor when viewed from below, but are fine from the side or above. At native resolution it's pixel perfect, with zero cropping or aliasing, as you'd expect for a desktop monitor.  

For 480p/i it is mildly blurry but with very mild aliasing. Given that 480p/i was meant to display on a CRT the amount of blur is probably ideal. You can't set the aspect ratio to 4:3, so the aspect ratio is wrong, though. 

720p is also mildly bury, but has much more aliasing. It's ok at best. 

Although it's a desktop oriented display it does support interlaced modes and will track pretty much any resolution handed it so long as the refresh rate is 75 or lower. Deinterlacing is done by the BOB method.

It accepts VGA and DVI input. Because my tests device only outputs HDMI I used an adapter to plug into DVI but it didn't seem to hurt the image quality at all. VGA input has the same timing as the DVI port.

Input Lag

This display does not have a game mode, and other than colors it doesn't really have any settings. No display setting changed lag. I used a piLagTesterPRO to measure input lag. This device sends a frame of video over HDMI and measures how long it takes to display it.

It supports both 60hz and 75hz. Except where noted below I used 60hz.

Full Test Results 

I report two kinds of values. 1st response measures how long it takes for the TV to start responding (I use a 5% change in display brightness). This overly optimistic value doesn't tell how long it takes to see anything useful, but matches what other reviewers call input lag. full response is a more realistic measure of lag, and requires the display to reach 80% of it's final brightness. This combines both input lag and response time, and is closer to what you would actually experience in a game.

Resolution1st responsefull response1st responsefull responsescan outresponse time

The input lag is excellent, as is often seen for TN panels, even ancient ones like this, ranging from 2.8 to 5ms. The response time was about 18ms for TV modes, but was a bit lower for native resolution,  around15ms. This difference was repeatable but somewhat hard to explain. Normally differences in RT have to do with the reduced brightness range used in TV modes, but this LCD has the same RT no matter what the brightness transition. So maybe there's a different circuit that handles native resolution. 

You'll notice that interlaced and progressive modes have nearly the same lag. That's because this display has built in bob deinterlacing, which causes a decent amount of flicker but no lag. I didn't see any afterimages develop from the flicker, and I wouldn't expect it to, but I only ran it that way for a few minutes. 

The final thing to notice is that the full response at the bottom of the screen is about 3ms faster in 75hz mode than 60hz. This means the LCD really can refresh at 75hz, as reflected in the significantly faster scan out time in 75hz mode. Some displays are advertised as 75hz compatible but actually draw at 60hz and drop frames in order to keep up. Another win for a very old LCD. 12

Results compared to other displays

To allow quick comparison between many display I've summarized the results across all the displays I've personally tested with the piLagTester Pro. Min lag is the first response at the top of the screen, real lag is the full response at the bottom. The list is sorted by real lag in native mode, so this display gets a boost from support 75hz. 

all values are in ms
DisplayYear made (TV?)Native Resnative min lagnative real lag480i real lag480p real lag720p real lag1080p real lagnative response timenative scan out
Dell E198FPb20081024p2.720.439.035.05.0012.70
Vizio VO370M20101080p2.523.683.
Dell U2410 (game)20101080p4.
AOC/Envision G19LWK2010900p3.131.239.538.738.437.815.5012.60
Dell E2211H20141080p3.033.634.734.534.133.815.0015.57
Panasonic TH-58PE75U2008720p28.
Dell 1907FPc20081024p3.034.035.934.815.0016.00
Corprit D157 (hdmi)20211080p3.134.534.934.834.633.916.2515.13
Samsung S27C23020141080p2.936.136.636.137.018.2514.97
Vizio E470VL (vga)20111080p22.
Dell U2410 (sRGB)20101080p20.542.862.445.
RCA L40FHD4120101080p20.346.665.
Sony 40VL130 (game)20081080p22.847.366.349.047.347.39.0815.43
Polaroid FLM-373B2007720p28.
Philips 42PFL3603D/F720091080p29.
Emprex HD 32022007720p27.050.5126.
LG 42LC2D2006720p28.350.654.650.850.46.3015.95
GPX TDE3245W2016720p28.051.0102.
Sony KDL-46EX40020101080p28.
Toshiba 40L2200U20141080p30.
Vizio VO22L FHDTV10A2008720p28.
Sharp LC-C3234U2009720p33.064.683.666.664.615.0016.60
Toshiba 46L5200U20131080p55.
Sony 40S20L12007720p48.472.090.172.973.49.6014.00
Samsung HP-T425420111080p69.775.794.
LG 47LW6500-UA20121080p66.680.7149.7149.081.780.92.2711.83
Vizio E470VL (hdmi)20111080p69.086.0128.

Response time is a bit slow, but the sum is still very competitive. Despite the age it's still one the fastest displays I've tested.  It seems that TN displays have had low lag for a long time. On the other hand, the long response time means that motion will be a little blurry so it's definitely not an ideal gaming monitor. But heck it's not bad, at this price range especially. 


I strongly prefer IPS panels for their accurate color over wide viewing angles. A good IPS display will cost more than a TN display, but will almost certainly be slower. If you are primarily concerned with gaming TN might be the way to go, though of course not every TN display is optimized for low lag and fast response.

Other models

I tested the AOC Envision G19LWK model, which is the 19" version. There appears to be two versions of this panel: the G19LWK and the G22LWK.  Based similarities in their names, specs and release date I suspect that they would perform similarly, though the G22LWK is higher resolution. Honestly, the TN displays from this era that I've tested all perform quite similarly; probably any TN model would be about the same league, at least in terms of lag. I have noticed that many do not support interlaced modes however so if you interests are retro you might need to be more choosy. 

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