P-76: Perceptual Tests of the Temporal Properties of a Shuttered LCD Projector

Abstract

Perceptual motion blur was studied in imagery presented on an LCD projector equipped with a mechanical shutter to reduce pixel hold‐time. Perceptual measures of image blur were obtained with both a simple test stimulus, as well as real‐world imagery. Both were found to correlate well with the measured pixel hold‐time.

P‐39: Perceptual Tests of the Temporal Response of a Shuttered LCoS Projector

“…Stimuli and Apparatus. The test stimulus was a pair of vertical lines (20° in length) that moved horizontally across the display, and whose separation could be varied [5][6]. The test-stimulus varied in speed from 100 to 1200 pixels/second (5.6 to 67.5 degrees/sec).…”

“…In a previous paper [5], we reported that an LCD projector equipped with a mechanical shutter that reduced pixel hold-time by approximately 33% resulted in a significant reduction in perceived blur. Further, experienced pilots who viewed the resulting imagery rated moving image quality as significantly higher when the shutter was used.…”

“…Display temporal response was measured for each of the LCoS-display shutter conditions and for the CRT using a photodiode-based circuit and an oscilloscope. The photodiode was directed at a 30 Hz flashing square generated by our test program [5,6,10]. A Fluke ScopeMeter was used to record the photodiode response.…”

“…However, the onset and offset times of LCDs have been reduced significantly over the past ten years, and so their limited temporal response seems now to be a consequence of the sample-and-hold property related to both the design of the LCD driver circuitry and the LCD itself [4]. It has been concluded, from temporal resolution measured using a simple moving line stimulus, that a hold-time of approximately 8 msec or less, as opposed to the current 16.7 msec, significantly reduces motion blur [5,6].…”

59.5L: Late‐News Paper: Evaluation of a Prototype Grating‐Light‐Valve Laser Projector for Flight Simulation Applications

“…However, tracking blur, which occurs when an observer tracks moving imagery, is greater for most digital projectors due to a longer within-frame hold-time than that of CRTs [6,7]. Digital projectors can be relatively easily modified to reduce their holdtime, and we have previously evaluated several such projectors for possible use in flight-simulator applications [12,13]. Those evaluations verified the high contrast and spatial resolution of digital projectors, and also indicated that tracking blur could be reduced sufficiently for use in many simulator applications.…”