PixPerAn – Pixel Performance Analyser
LCD monitors are in many ways superior to CRT monitors. However, there is one distinct trait in which LCDs perform significantly worse than CRT monitors: The clean reproduction of swift and fluent movements. This is due to no less two reasons:
1) The response time of the display elements of a LCD monitor are significantly slower than those of the phosphor layer of a common CRT monitor. So it takes the pixel a while to change its brightness from the old value to the new one.
2) The brightness of a pixel in an LCD monitor is sustained throughout the entire duration of a single frame, each pixel of a CRT monitor only flashes up very shortly per single frame.
On one hand, this is a huge advantage for LCDs: They do not flicker – no matter how low the vertical frequency is set. (The vertical frequency determines how many single frames are transferred from the graphics card to the monitor. For this reason, LCD monitors use a vertical frequency of 60 Hz most of the time; a value that would result in very noticeable flickering for CRT monitors.
On the other hand, this sustaining of brightness causes a blurring effect on rapid movements which, in any case, occurs independently from the response time.
Motion blur can make subtle details become indistinct to an unrecognizable extent. There often is a distinct trail noticeable behind quickly moving objects. These “streaks” (which is how this motion blurring is being called in our message board) are hard to judge from an objective point of view. Different observers perceive them by all means differently which is why observations of streaks can barely be communicated in a comprehensible way.
In order to establish a basis allowing response times of LCD monitors to be compared, various pieces of test software were developed. The utilized tests basically rely on the perception of the user however and, for this reason, have to be regarded as objective to a certain degree only. The test software PixPerAn that is shown here incorporates various different test methods in order to produce results that are as much meaningful as possible.
Download: PixPerAn 1.011e