Template:Settling goal

Side note: Both modes, flicker-free and strobed backlight, can be equally useful, but it all depends on the application. Strobed backlight is certainly useful when it comes to presenting motion stimuli and avoiding motion blur, no matter whether the stimuli are possibly tracked with the eyes. Strobed backlight also offers a basically instant and fully synchronous stimulus onset and offset, which comes, of course, with flicker that is usually not meant to be part of the stimulation. Synchronous stimulus onset means that the stimulus appears at all screen locations at the same time (sufficient settling performance assumed).

Flicker-free backlight, on the other hand, is useful for static stimuli or for stimuli which are animated in place, meaning for stimuli which do not move but are possibly switched on and off at fixed locations. The stimulus onset and offset is not as instant as with strobed backlight, and the screen is not updated all at once but, instead, from top to bottom. However, there is no flicker unless flicker is intended to be part of the stimulus.

Actually, both backlight modes have aspects that are similar to the operation mode of the good old CRTs. The pulse-like excitation of the phosphors is more similar to the strobed backlight mode, whereas the line-wise screen refresh is more similar to the flicker-free backlight mode.

The goal behind representing the settling behavior by a few graphs and numbers is to quantitatively rate the performance of a monitor and to compare it with other monitors or the requirements of the application at hand. It is difficult, however, to come up with a set of performance measures that is small, easy to understand, easy to measure, and of practical relevance. What is practically relevant depends, of course, on the application at hand and on the properties the monitors actually can differ in. Regarding the latter, an overshoot measure, for example, does only make sense if the monitors actually differ in overshoot behavior, which they only do since overdrive technologies have been implemented. So to some extent, the set of performance measures needs to be adapted to the ever changing monitor technology. Using an inappropriate set of performance measures is not only misleading us, the customers, when looking for a good monitor but might also make manufacturers optimize monitors in the wrong way.

In order to quantify things as objectively as possible, the numbers should be based on physical measurements. However, what matters in the end are not the physical properties directly but their impact on our perception as the signal travels through the visual system. Unfortunately, quantifying perception and inferring perceptual quantities from the physical properties is not as trivial as it might seem. We know a few things about the visual system, but this knowledge is derived from rather specific experiments that were run under well controlled lab conditions and do not necessarily translate well into real world scenarios where many more factors play a role. One example, which is also relevant for monitor characterization, is Weber's law, which basically says that the visual system's sensitivity for luminance differences scales with the luminance level at which the differences are observed. Sensitivity for a luminance change is higher for dark stimuli than it is for bright stimuli. However, in how far Weber's law holds for a given spatial stimulus configuration or even for dynamically changing scenes cannot be easily inferred just from the simple case/experiment for which Weber's law has been found true. Even if we had an accurate model of how the test stimuli are processed by the visual system, we still would not know how well the test stimuli adopted for the measurement taken here are representative for arbitrary image sequences in real world applications.