Da-Hai Li

Autostereoscopic display based on two-layer lenticular lenses

An autostereoscopic display based on two-layer lenticular lenses is proposed. The two-layer lenticular lenses include one-layer conventional lenticular lenses and additional one-layer concentrating-light lenticular lenses. Two prototypes of the proposed and conventional autostereoscopic displays are developed. At the optimum three-dimensional view distance, the luminance distribution of the prototypes along the horizontal direction is measured. By calculating the luminance distribution, the crosstalk of the prototypes is obtained. Compared with the conventional autostereoscopic display, the proposed autostereoscopic display has less crosstalk, a wider view angle, and higher efficiency of light utilization.

Autostereoscopic three-dimensional projector based on two parallax barriers

An autostereoscopic 3D projector using several 2D projectors, a projection screen, and two parallax barriers is proposed. Parallax barrier 1 facing the 2D projectors collimates the images that have aberrations on the edge of the projection screen. Parallax barrier 2 facing viewers acts as the parallax barrier in ordinary autostereoscopic 3D displays. The operation principle of the system, the calculation equations for the parallax barriers, and the capture and correction of parallax images are described in detail. A 60-inch autostereoscopic 3D projector prototype having four 2D projectors was developed. The presentation of 3D static, animation, and video images is realized by the prototype. The prototypes stereoscopic images without aberrations and with a little cross talk are sharp. Especially, its 3D resolution is the same as its 2D resolution.

Edge-Lighting Light Guide Plate Based on Micro-Prism for Liquid Crystal Display

We designed an edge-lighting light guide plate (LGP) based on a micro-prism structure for liquid crystal display. Its top and bottom surfaces have micro-prisms, and a layer of high reflection film is coated on the bottom surface. The principle of the LGP was analyzed. The optical simulation tool ASAP was used to calculate the apex angle and height of the micro-prism on the top of the LGP, the apex angle of the micro-prism on the bottom of the LGP and the emitting angle dependent luminous flux of the LGP. By adjusting the width of micro-prisms on the bottom, the LGP achieved uniform luminance. A 12-in LGP based on a micro-prism structure as an example was designed. The results proved that the LGP based on a micro-prism structure is thin and simple with uniform luminance and high efficiency.

An integral-imaging three-dimensional display with wide viewing angle

— The viewing angle and flipping areas of a conventional integral-imaging three-dimensional (3-D) display were analyzed. The pitches of the elemental image and micro-lens are identical. The more micro-lenses used, the smaller the viewing angle becomes and the wider the flipping areas become. In this paper, an improved integral-imaging 3-D display is presented. The pitch of the elemental image is larger than that of the micro-lens. The single-viewing angles of all micro-lenses converge and there are no flipping areas at the optimal viewing distance. Computational reconstructions of improved and conventional integral imaging were carried out, and experimental results demonstrate that improved integral-imaging 3-D displays have a wider viewing angle than the conventional ones and do not have flipping areas at the optimal viewing distance.

Image Processing to Eliminate Crosstalk Between Neighboring View Images in Three-Dimensional Lenticular Display

In the multiview autostereoscopic 3D lenticular displays, the crosstalk between the neighboring view images at each view images optimal viewing position influences the image quality and lowers the visual comfort of observers. A method is proposed to eliminate the crosstalk by correcting the intensity values of subpixels on synthetic images. We analyze the causes of crosstalk based on a synthetic image and deduce the equations of crosstalk elimination according to the relationship between the crosstalk coefficients of each view image observed through the lenticular sheet, the intensity values of subpixels displayed on the synthetic images, and the intensity values of subpixels observed through the lenticular sheet at the optimal viewing position. The experiment results verify the effectiveness of the proposed method. The method for crosstalk elimination is by means of image processing, and it does not change the parameters of the lenticular lens and the structure of the display screen.

Dual-view integral imaging three-dimensional display

In this paper, we propose a dual-view integral imaging (DVII) three-dimensional (3D) display that presents different 3D images in the left and right viewing directions simultaneously. The DVII 3D display consists of a display panel and a microlens array, and its elemental image array (EIA) is composed of two sub-EIAs. The sub-EIAs captured for two different 3D scenes are responsible for two different 3D images in the left-view and right-view integral imaging 3D displays, respectively. A prototype of the DVII 3D display using a pinhole array is developed, and good results are obtained.

Cross-talk reduction by correcting the subpixel position in a multiview autostereoscopic three-dimensional display based on a lenticular sheet

A method is proposed to alleviate the cross talk in multiview autostereoscopic three-dimensional displays based on a lenticular sheet. We analyze the positional relationship between subpixels on the image panel and the lenticular sheet. According to this relationship, optimal synthetic images are synthesized to minimize cross talk by correcting the positions of subpixels on the image panel. Experimental results show that the proposed method significantly reduces the cross talk of view images and improves the quality of stereoscopic images.

Pixel Arrangement of Autostereoscopic Liquid Crystal Displays Based on Parallax Barriers

The methods of pixel arrangement for autostereoscopic liquid crystal displays based on conventional vertical parallax barriers are summarized. A novel method of pixel arrangement for autostereoscopic liquid crystal displays based on step parallax barriers is proposed. The pixel arrangements are given for different inclined angles of parallax barriers and different column numbers of images. A demo of the autostereoscopic liquid crystal display using the new method of pixel arrangement presents very good stereo images. The results help to solve the process, storage and transmission of stereo images of autostereoscopic liquid crystal displays based on parallax barriers.

Improved formula of wavefront reconstruction from a radial shearing interferogram

A radial shearing (RS) interferogram obtained by the carrier fringe method is essentially the combination of radial and lateral shearing. The previous phase reconstruction algorithm neglects the effect of lateral shearing on the obtained RS interferogram. A mathematical formula for wavefront reconstruction from an RS interferogram is deduced. If the phase difference of the tested wavefront phase, the RS ratio s, and the laterally sheared amount x(0) in the x direction and y(0) in the y direction, respectively, have been determined, the tested wavefront phase can be precisely reconstructed using this formula. The result of simulation analysis and experiment shows that the formula is correct and more accurate.

Tilted elemental image array generation method for moiré-reduced computer generated integral imaging display.

In this paper, we propose a tilted elemental image array generation method for computer generated integral imaging display with reduced moiré patterns. The pixels of the tilted elemental image array are divided into border pixels and effective pixels. According to the optimal tilted angle, the effective pixels are arranged with uniform arrangement. Also, a pixel mapping method is proposed. Appropriate experiments are carried out and the experimental results show that not only the color moiré patterns are reduced remarkably, but also the resolution of the reconstructed 3D images are improved through the proposed method.