Acer Predator XB271HK 27″ 4K Monitor Review
Panel Backlight Bleed
An LCD or LCD LED based monitor relies upon either one or multiple sources of light to illuminate the Liquid Crystals so as to create an image that consumers can see. In a perfect world all the light would either go through the open Crystals or be reflected back into the interior of the display via the closed crystals. Due to manufacturing process most monitors exhibit light leakage around the edges of the monitor. This issue is called Backlight bleed and can drastically lower the contrast near these effected areas. This causes colors to have a ‘washed out’ appearance with blacks appearing to be more gray that black. Optimally a monitor should have zero bleeding, but if the amount is judged to be minor enough we will consider it to be adequate.
To determine the amount – if – any backlight bleed a given samples exhibits we have placed the monitor in a completely dark room, and using a Nikon D810 w/ 24-70 f2.8E VR lens have taken a series of pictures of the monitor. In between each shot the ISO is raised by one stop until a picture is captured that shows the amount of bleed occurring.
Due to variances in lumen output from one model to another we have chosen a setting of 250cd/m for the brightness setting instead of a percentage output. This amount of light is brighter than most consumers will be comfortable using, and yet any modern monitor is capable of producing this amount of light. As such it represents a good, but still realistic, worst case scenario.
As you can see the left side (its left) of the monitor shows an all but imperceptible amount of bleeding along the edges and corners. The top right has an extremely minor amount of bleed and the lower right has a moderate amount. To the naked eye the only bleed appears to come from the bottom right corner but it is extremely limited. To put this amount in perspective we had to raise the ISO from base setting of 64 all the way to 4,000 to obtain an image that was anything but ‘black’ – as the light leaking from the screen was that minor.
Gamma correction is one of the hardest terms to explain. However, for our purposes the gamma correction of any electronics device is how bright or dark an image will be displayed on a screen.
All PC devices now use 2.20 gamma as the default. Any variance from this will result in an image being either underexposed which will create black crush and underexposed shadow detail or washed out with too little black level detail (aka being over-exposed).
While 2.20 is the gold standard, a minor deviation of 0.10 will in all likelihood never be noticed by anyone other than professional photographers. Higher levels of deflection however will be noticed by just about everyone.
The XB271HK may have a gamma ratio that is slightly inferior to our XB270 sample, but this amount is still within tolerances. By the same token, given the asking price of the XB271HK we would have preferred it to come factory calibrated to a perfect level and remove such variability.
- Menu Layout & Observations
- Panel Uniformity / Panel Performance
- Panel Backlight Bleed / Gamma Performance
- Colour Saturation Levels / Default RGB Levels
- Viewing Angles / Contrast Ratio / Power Consumption
- Gaming Performance
- Movie Performance
- Non-Colorimeter Tweaking and Results
- Conclusion; One of the Best Just Got Better