The last CRT survey (page 6: Game quality)

Game quality

If some gamers remain faithful to CRTs, it’s because they feel they provide better reaction time because of the following reasons:

They aren´t subject to afterglow

They display more images per second

Let´s begin with the second point, the rate of sequences. LCDs work at 60 to 75 Hz, ideally with vertical synchronisation activated on the graphic card. 60 to 75 "full" images are displayed.

We remind you that when vertical synchronisation is activated, the graphic card will wait for the image to be read and then send it to the monitor via RAMDAC or TDMS before writing in the front buffer the one that has been temporary calculated and written in the back buffer. If you chose to deactivate this synchronisation, the passing from the back buffer to the front buffer will be made at anytime: The image sent and displayed by the monitor will be partly divided, or depending on the framerate images will be calculated by the GPU. This will lead to images freezing and breaks in the continuity seen on the screen. It is preferable to play with the synchronisation activated.

So a LCD monitor at 60 HZ will display 60 images per second. This frequency is a turn-off for most hardcore gamers.
They would be inclined to use a CRT that will allow much higher frequencies at 120 Hz or above.

We placed one of our three CRTs in clone mode with an LCD and the latter takes a severe beating. We didn’t try to be nice as this test is extremely severe for current flat monitors. The result is so different that even our colleagues that don´t see afterglow on a 25ms monitor see it here. Going back to an LCD after this is really difficult. On CRTs, even if the phosphorus sometimes shows a persistence of images and even if in office mode we find them blurred at certain frequencies, games are superb.

Reaction 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 in front of objects in motion.

With the CRTs we captured afterglow with a camera at a shutter speed of 1/60 seconds as compared to 1/1000 s for LCD. We take 50 pictures per test. We then can see a monitor´s ghosting effects, or all the car´s positions 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. Why 1/60 Hz? Becase it is the monitor refreshing rate. Beyond his figure, we capture black areas that are due to the monitor screening.

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

Iiyama MA203DT

Philips 109B60

ViewSonic P227FB
Here is the comparison with one of the fastest LCD on the market:

ViewSonic VX922, TN 2 ms panel
Not only is it obvious that the LCD monitor has a higher level of afterglow, but there is something else. For the CRT, images are drawn by a beam that screens the monitor. They are only affected for a few nanoseconds. After the passage of the beam, the image doesn’t immediately fade away because of the phosphorus persistence, whose role is to capture light and restore it in a few milliseconds. Nevertheless, the image turns to black and this is so fast that our eye doesn´t see it. It can´t be perceived but it sometimes causes visual tiredness (this is a separate problem).

With LCDs, manufacturers have now enabled the display of full images without transitions. Our eye is subject to a small persistence of images, however, that last a few milliseconds. Fast liquid crystals aren´t enough. According to the latest manufacturer studies, our eyes add some afterglow by keeping in memory the previous image. This afterglow isn´t captured with our camera. This phenomenon explains the gap between what we sees on LCD monitors when we launch PixPerAn and the sharpness of objects captured by our camera.
This is the reason why BenQ, Samsung, LG-Philips and CMO work on an artificial reproduction of the screening on the fastest LCD to clean our eyes from the previous image. This is what we gathered from the CeBIT in inquiring about BFI, MPA, and 120 Hz.