Tuesday, March 18, 2008

BFI in practice: games

he BFI in practice
We might be afraid of two things due to the introduction of this innovation:

- a significant loss of brightness
- variations in the homogeneity of brightness.

Unfortunately, our fears were confirmed.

One good point, however, is that the afterglow noticeably diminished once the BFI was activated and the improvement was obvious. We estimate that it was cut in half, however, we are also sure that some of you won't activate it in games. Why? Because the screening at 60 HZ might be too disturbing for some. In fact, you end up having to choose between the lesser of two evils. Is it better to have a slightly blurred image or rendering that twinkles? After a few days of gaming, we found that this depends on the game. Some have rather homogenous images (strategic games, for example) and the screening of the black area could be disturbing. In this case, we preferred playing without BFI and fortunately, this is where afterglow is the least disturbing. We don't need perfect reaction time for this type of game and we can make do with a slight blur of the image when units are moving.

Then there are FPS, in which the character is always moving. Here, we weren't disturbed by the neon switching on and off. However, if you are a "super demanding" user, you won't be able to play with the BFI activated and you will regret buying this monitor. Don't concentrate on this point too much. Play your games and then adapt the monitor to your use, perhaps adjusting the BFI intensity (three levels are available in the OSD) according to your perception after one hour of gaming.

Reaction time test
A car moves from left to right at high speed.

Movement isn’t perfectly fluid. Depending on its speed, the car is shown in several successive positions. If the car goes very fast, the positions are very close and the eye perceives a flowing movement.
Perfect monitor
monitor with 3 ghost images

A monitor without ghosting effects would have previous images completely fading away when a new one appears. This is the theory and in practice, it's often not the case as images fade progressively. Sometimes up to 5 afterglow images remain on the monitor and represent the visible white trail behind objects. Some monitors have strong overdrives in addition to image anticipation algorithms. In this case, an image can appear in front of the main object, creating a white halo ahead of objects in motion.

With CRTs we captured afterglow with a camera at a shutter speed of 1/60 seconds as compared to 1/1000 s for an LCD. We take 50 pictures per test. We then can see a monitor’s ghosting effects, or all the car’s position in the entire process. The most important image is the one on the left, the better one. It will be the most displayed on the monitor, while the one on the right is in transition.

Here are the two extreme states with each monitor as afterglow oscillates.

BenQ FP241WZ, PVA 6 ms with BFI activated at 3

BenQ FP241WZ et FP241W, PVA 6 ms wihtout BFI.

Dell 2407WFP, S-PVA 6 ms

Afterglow in pictures is unchanged in all three monitors. This proves that the BFI doesn't have an impact on the reaction time of pixels. The BFI has an impact on our eyes, more specifically, on retinal persistence.


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