Sergey Shestak

10.4: Measuring of GraytoGray Crosstalk in a LCD Based TimeSequential Stereoscopic Display

A method of measuring stereoscopic crosstalk between left and right image pixels with arbitrary gray levels is proposed. The primary purpose of the method is to study LCD based timesequential stereodisplays, however the proposed method can be applied in studying and characterization of the other types of stereoscopic display. To test a method, a display, based on TN LCD panel, is examined. Noticeable variations of the crosstalk with the applied graygray input signals are demonstrated. It is also shown an asymmetry of the crosstalk, responsible for the light ghosting and a crosstalk, responsible for the dark ghosting.

Application of Pi-cells in time-multiplexed stereoscopic and autostereoscopic displays based on LCD panels

We investigated Pi-cell based polarization switches regarding their applications in both glass type and autostereoscopic 3D displays, which employ LCD as an image panel. It is found that Pi-cell should be divided into the number of individually addressable segments to be capable of switching in synchronism with line-by-line image update in order to reduce time-mismatch crosstalk. We estimated the number of segments, sufficient to reduce local and average crosstalk to acceptable level. It is found experimentally that the displayed stereoscopic image has unequal brightness and crosstalk in the right and left channels. The asymmetry of stereoscopic image parameters is probably caused by the asymmetry of rise/fall time, inherent in Pi-cells. The improved driving method capable of symmetrizing the crosstalk and brightness is proposed. It is also shown that the response time acceleration technique (RTA), developed for the reduction of motion blur, is capable of canceling the dynamic crosstalk caused by slow response of LCD pixels.

34.2: Field Sequential LC Barrier for a Full Resolution Auto-stereoscopic 3D Display

In this paper, we have developed 15.6 inch auto-stereoscopic 3D display with a field sequential LC parallax barrier which shows the full resolution image of the panel even in the 3D mode. By field sequential switching of a barrier and an image panel, we can compensate the loss of the resolution in the LC barrier type 3D display. We also investigated the field sequential switching effect on the performance of the LC parallax barrier type 3D display.

How much crosstalk can be allowed in a stereoscopic system at various grey levels

We have calculated a perceptual threshold of stereoscopic crosstalk on the basis of mathematical model of human vision sensitivity. Instead of linear model of just noticeable difference (JND) known as Webers law we applied nonlinear Bartens model. The predicted crosstalk threshold varies with the background luminance. The calculated values of threshold are in a reasonable agreement with known experimental data. We calculated perceptual threshold of crosstalk for various combinations of the applied grey level. This result can be applied for the assessment of grey-to-grey crosstalk compensation. Further computational analysis of the applied model predicts the increase of the displayable image contrast with reduction of the maximum displayable luminance.

Stereoscopic three-dimensional television using active glasses with switchable refraction

Abstract. We have devised a full-resolution stereoscopic television system incorporating both a patterned retarder and active glasses. Selective vision of the left image by the left eye and the right image by the right eye is achieved by a conventional combination of a patterned retarder and left and right polarized filters. Full resolution is provided by the active components of the glasses acting as a switchable refractive-type beam displacer. Pairs of line-interleaved images are displayed on an LCD screen sequentially at a frame rate of 120 Hz. With the help of active refraction glasses, the viewer can see full-resolution stereoscopic images as if they are displayed in an interlaced manner. Active glasses are flicker-free. Measured stereoscopic crosstalk is 0.6%, which is defined only by the performance of the patterned retarder.

Flicker-free shutter glasses for full high-definition 3D viewing

Three-dimensional displays based on shutter-glasses offer full resolution, high-fidelity stereoscopic images. Left and right perspectives are displayed in a sequence on the same TV screen. Conventional shutter glasses use a liquid crystal (LC) cell enclosed between two polarizers to alternately block the left and right eyes from viewing the ‘wrong’ image so that the left image is viewed by only the left eye and the right image by only the right eye: see Figure 1(a). If the ambient light source is much brighter than the TV screen image, the viewer may perceive flicker.1 Another source of perceived flicker is artificial light sources, most of which emit light modulated at a high frequency. Although they are not normally perceived as flickering, interference between the light source modulation and the shutter switching can be perceived as a (lower) frequency flicker: see Figure 1(b). In conventional shutter glasses, a pulsed voltage is applied to the LC cell and (via a microcontroller) synchronized with the TV set by an IR or RF signal. The shutter is opaque when the voltage is ON and translucent when the voltage is off. Since the light emitted by the LCD panel is polarized, the front polarizer facing the screen can be removed without loss of functionality: see Figure 2(a). However, omitting the front polarizer to improve flicker creates another problem. When the viewer’s head is tilted, there is severe ghosting on the stereoscopic image caused by ‘crosstalk’ between the left and right images: the left eye receives some of the image intended for the right eye and vice versa. One way to overcome this is to apply a tilt-dependent voltage to the LC cell. We found that a better design for the shutter replaces the front polarizer with a quarter-wave retardation film. This has fast and slow orthogonal principal axes. Incident light polarized parallel to either principal axis is unchanged, but incident light polarized between the axes is transformed to elliptically polarized light Figure 1. (a) Ambient light condition and shutter’s structure. (b) Low frequency flicker by interference of shutter and blinking light source. The shutters switch at 60Hz and the light source is modulated at 50Hz, providing perceived ‘flicker’ of 10Hz. LC: Liquid crystal.

Stereoscopic display technologies for FHD 3D LCD TV

Stereoscopic display technologies have been developed as one of advanced displays, and many TV industrials have been trying commercialization of 3D TV. We have been developing 3D TV based on LCD with LED BLU (backlight unit) since Samsung launched the worlds first 3D TV based on PDP. However, the data scanning of panel and LCs response characteristics of LCD TV cause interference among frames (that is crosstalk), and this makes 3D video quality worse. We propose the method to reduce crosstalk by LCD driving and backlight control of FHD 3D LCD TV.

Development of Time-Multiplexed Autostereoscopic Display Based on LCD Panel

The main advantage of time-multiplexed stereoscopic display is that high-resolution stereoscopic images can be displayed using single monitor. In a time-multiplexed stereoscopic system left and right images of a stereopair consequently appear on the screen of 2-D display. The viewer is able to see the left and right images separately due to special shutter glasses or passive polarized eyeglasses combined with a polarization switch, sequentially occluding the left and the right eyes, thus preventing the viewer’s eyes from seeing wrong images. Since conventional 2-D images and components of the stereopair may be displayed with the same full resolution of the image panel, 2-D / 3-D switching of the display is potentially unnecessary. Both 3-D and 2-D content can be displayed on the same screen simultaneously. Time-multiplexed stereoscopic systems, utilizing polarization shutter glasses and polarization switchable screens are well-known and have been the objective of much research [1,2,3,4,5]. The shutter glasses system has two wearable optical switches, capable of switching their transparency thus blocking the left or right eye. The passive polarized eyeglasses system has one large (screen size) optical polarization switch switchable between two

Full resolution stereoscopic television using flicker-free active beam displacement glasses

We have devised full resolution stereoscopic television system incorporating both patterned retarder and active glasses. Selective vision of the left image by the left eye and the right image by the right eye is achieved by conventional combination of patterned retarder and left and right polarized filters. Full resolution is provided by active components of glasses acting as a switchable beam displacer. Pairs of line-interleaved images are displayed on LCD screen sequentially at a frame-rate 120 Hz. Viewer can see full resolution stereoscopic images as if they are displayed in interlaced manner by active glasses. Active glasses are flicker free. Patterned retarder defines crosstalk level in a range below 1%.

Flicker-free 3D shutter glasses by retardnace control of LC cell

Ambient light inside viewing field of shutter-glasses 3DTV system can cause perceivable flicker due to high brightness of the light source. Omitting front polarizer of shutter glasses can be a solution for improving ambient light flicker, but it makes noticeable ghosting whenever 3D viewers tilt their heads. In this paper, we propose the new flicker-free shutter glasses compensated for viewers head tilt using tilt sensor. The crosstalk level, inserted by the shutter is below 1.6% within the tilt angle range from 0 to ±50°.