On Asus' Backlight Bleed: A Follow Up To Our Asus ROG Swift PG279Q Review

Last month, we reviewed the latest ROG Swift gaming monitor from Asus, the PG279Q. It’s a premium 27-inch display with an AHVA panel, G-Sync, ULMB and a max refresh rate of 165 Hz with overclock. It impressed us enough to earn an Editor Recommended Award, but all was not perfect with our sample. In the screen uniformity tests, we found some backlight bleed (aka "IPS glow"), in the lower-right zone of the screen.

Our test measures nine areas of the screen for luminance. The outer zones are compared to the center one in order to derive a percentage variation. That means lower numbers are better. In our experience, any monitor scoring under 10 percent for either the full white or full black field test has no visible variations in light output. To the eye, it will appear to render a smooth and uniform tone from edge to edge.

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So what does it all mean? In dark material, you will likely see a hotspot artifact, and it may or may not be distracting depending on the quality of your particular sample and the particular content you’re viewing. The issue is not an isolated one, and many users have reported visible light bleed on their PG279Qs. Fortunately for purchasers of the early production run, Asus is providing a solution by replacing defective panels.

This phenomenon is not that unusual among all types of LCD monitors. It’s caused by tiny variations in the gap between the first two screen layers. You’ve all seen what happens when you apply a bit of pressure to the screen with your finger: A glowing spot appears underneath. What you’re seeing is displacement of the crystals. Or in other words, the crystals become disoriented and allow more light through. This same pressure can be exerted by the anti-glare layer, causing a permanent hotspot. It’s more common in monitors that use a tight layer gap for clarity’s sake.

Manufacturers have to walk several thin lines with a mass-produced product. A tighter layer gap means a clearer picture, but it also means more panels will exhibit light bleed, because even the tiniest variation in flatness can cause the anomaly. Opening up the gap means fewer panels are thrown away, but it also reduces picture quality. Finding that happy medium is a challenge when you’re already selling displays at razor-thin profit margins.

We recommend inspecting any monitor thoroughly before committing, especially when you order it by mail. Light bleed can happen to any panel type – TN, IPS or VA, and their different variations. It all depends on how tight the layer gap is and what quality control measures have been taken to weed out defective parts before shipment. In the case of the PG279Q, Asus is maintaining its status as a premium display maker by taking care of dissatisfied customers.

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Christian Eberle is a Contributing Editor for Tom's Hardware US. He's a veteran reviewer of A/V equipment, specializing in monitors. Christian began his obsession with tech when he built his first PC in 1991, a 286 running DOS 3.0 at a blazing 12MHz. In 2006, he undertook training from the Imaging Science Foundation in video calibration and testing and thus started a passion for precise imaging that persists to this day. He is also a professional musician with a degree from the New England Conservatory as a classical bassoonist which he used to good effect as a performer with the West Point Army Band from 1987 to 2013. He enjoys watching movies and listening to high-end audio in his custom-built home theater and can be seen riding trails near his home on a race-ready ICE VTX recumbent trike. Christian enjoys the endless summer in Florida where he lives with his wife and Chihuahua and plays with orchestras around the state.

12 Comments Comment from the forums

sillynilly

Many times I have seen bleed mainly come from a tight bezel/housing or even the LCD panel's metal housing creating the hotspot - not so much from the layers themselves. Many times bleed goes away debezeling or in the worst cases adjusting the LCD layer metal surround. All in all pressure is baaaad! Good for ASUS stepping up and swapping panels.
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Larry Litmanen

I have an ultrawide monitor, it is GREAT. I was reading a review of the monitor after i purchased it and the review said that monitor had some backlight bleed. I looked and sure enough there was some.

I did not even know it was there before someone said it is there. I have never even thought about it again until this article.

It is just a trivial thing to focus on, it is really a non issue.
Reply
laststop311

I have an ultrawide monitor, it is GREAT. I was reading a review of the monitor after i purchased it and the review said that monitor had some backlight bleed. I looked and sure enough there was some.

I did not even know it was there before someone said it is there. I have never even thought about it again until this article.

It is just a trivial thing to focus on, it is really a non issue.

Trivial when you are paying a cheap price, not when ur paying 700.

Reply
milkod2001

i wonder if problems with Backlit Bleeding will go away with OLED screens or we could expect the same issues there. Anybody?
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SpAwNtoHell

I wanted badly either the rog ips or the predator ips but i had to settle in the end for the tn and a smaller screen size as i could not live with this gamble, in uk both rog and predator are about the same price 700£... If ordered online as in retail storeyou can add another 100 easy. So bottom line i took my chance with tn 24" aoc telling to myself if worse comes to worse my loss will be less then half also my dissapoitment in the monitor. This is not a perfect monitor but is not as bad as assus and acer reports. I am very curious when oled hits the desktop if the problem persists..
Reply
Chetou

"In the screen uniformity tests, we found some backlight bleed (aka "IPS glow")"

Backlight bleed and IPS glow are two different things!
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hdmark

i wonder if problems with Backlit Bleeding will go away with OLED screens or we could expect the same issues there. Anybody?

I don't think there is even potential for backlit bleeding with OLED because there is no backlight. im not sure how its layered or if there are layers even, but im assuming there will/could still be other issues, but backlight will not be one of them

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Uri___Pisarev

I have an ultrawide monitor, it is GREAT. I was reading a review of the monitor after i purchased it and the review said that monitor had some backlight bleed. I looked and sure enough there was some.

I did not even know it was there before someone said it is there. I have never even thought about it again until this article.

It is just a trivial thing to focus on, it is really a non issue.

Trivial when you are paying a cheap price, not when ur paying 700.

I paid around 1K for my Dell. It's one of those internet problems, people need to find something to complain about, something that is meaningless in real world usage.
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chumly

"IPS Glow" and backlight bleed are not the same things. One is caused by the backlight escaping the edge of the bezel or frame and "bleeding" light onto the edge of the picture. IPS Glow is the inherent glow when viewing blacks at an angle.

If I want a monitor review I use tftcentral.co.uk. Maybe some of Tom's employees could get a lesson on how to do a monitor review from them :)
Reply
Johnpombrio

I just got my ASUS PG279Q monitor in a couple of days ago. It was made in Jan, 2016 and there is no hotspots that I can tell. I cranked the brightness up to max and fooled with the contrast. Completely uniform and minimal bleedthrough. Bringing the brightness down to usable levels (around 50 for brightness, saturation, and contrast of 42) gives me a terrific picture, noticeably better than my 2 year old Dell. I wonder if the newer builds have compensated for this issue? GREAT monitor for gaming BTW!
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