P-92: Motion Blur Estimation on LCDs

Today there is no requirement concerning LCD motion blur in TCO Requirements ( e.g. TCO'06 Media Displays). The primary goal of this study is to find a measurement method for motion blur which is easy to carry out and gives reproducible results lab to lab. This method should be able to take in account motion blur reduction systems such as backlight flashing. Measurement results and method proposal are given. 1. Introductionrecent improvements to LCD technology such as response time compensation, LCD motion blur remains very annoying for sequences with rapid movements. In fact, even if the response time of a liquid crystal matrix was reduced to zero, motion blur would still appear. This is due to sample-and-hold behaviour of the display; the light intensity is sustained on the screen for the duration of the frame, whereas on a CRT light intensity is a pulse which fades over the frame duration. LCD displays are so called hold-type displays. The main difference happens when the eyes of the observer are tracking a moving object on the screen; for a given frame, the picture is still on the screen while the eye is still moving slightly anticipating the movement of the object. Edges of this object are integrated on the retina while moving, resulting in a blur [1]. The most common metric to characterize LCD motion blur is the MPRT (motion picture response time) [2] and its relative indexes BET and BEW 1 . A lot of measurement systems have been developed in order to measure MPRT [3], but they are generally quite expensive and complicated to carry out. As a consequence, alternative approaches have been proposed, based on the theoretical analysis of the display spatial and temporal apertures. It has been shown that MPRT can be obtained from the temporal impulse response [4][5] or from the temporal step response [6][7] instead of measuring the blur width spatially. First comparisons between the results of simulation methods and those of measurement systems showed that both approaches are very close [3][8]. However, these investigations only concerned few displays. Further measurements should be done in order to analyse the difference between the results of these two approaches. Today there is no requirement concerning LCD motion blur in TCO'06 Displays [9] and the requirements concerning response time is not sufficient to guarantee a low level of motion blur annoyance. In particular, display devices with impulsive driving techniques to reduce motion blur such as backlight flashing (BF) and black data insertion (BDI) have difficulties to obtain the TCO label concerning response time. Actually, it's difficult to measure response time in a classical way when these motion-blur reduction techniques are present. The primary goal of this study is to find a 1 respectively blurred edge time, blurred edge width.