Image Crosstalk Research Articles

Viewing-Angle-Enhanced and Dual-View Compatible Integral Imaging 3D Display Based on a Dual Pinhole Array.

Conventional integral imaging (InIm) three-dimensional (3D) display has the defect of a small viewing angle and usually presents a single 3D image. In this paper, we propose a viewing-angle-enhanced and dual-view compatible InIm 3D display system. The crosstalk pixel areas within the conventional elemental images (EIs) that result in image crosstalk were effectively utilized either for viewing angle enhancement or for dual-view 3D display. In the viewing-angle-enhanced 3D display mode, a composite elemental image (CEI) that consisted of a normal EI and two view-enhanced EIs was imaged by a dual pinhole array and formed an extended 3D viewing area. A precisely designed mask array was introduced to block the overlapped rays between adjacent viewing areas to eliminate image crosstalk. While in the dual-view 3D display mode, a CEI was composed of image information of two different 3D scenes. With the help of the dual pinhole array and mask array, two different 3D images were reconstructed for the left and right perspectives. Experiments demonstrated that both the left and right sides were increased by 6 degrees from the conventional 3D viewing angle, and also, a dual-view 3D display effect that retains the same viewing angle as the conventional system was achieved. The proposed system has a compact structure and can be freely switched between two display modes.

Visual angle enlargement method based on effective reconstruction area

The traditional integral imaging system has a small viewing angle, mainly due to the existence of interference pixels in the generated element image. At the same time, in the 3D reconstruction scene, the content that is not in the effective reconstruction area will also cause image crosstalk between adjacent viewpoints, which affects the display angle. In this paper, a viewing angle enlargement method based on an effective reconstruction area is proposed to establish the correspondence between the point pixels in the element image and the micro-lens in the micro-lens array, and the pixel information in the pixel recombination area is derived and updated. The effective reconstruction area is used for constraint, so as to enhance the effective use of the element image information. The experimental results show that the element image with the pixel update has a larger viewing angle and clearer reconstruction content.

Reducing Defocused-Information Crosstalk to Multi-View Holography by Using Multichannel Encryption of Random Phase Distribution

A new optical encryption algorithm, called the random-phase encryption algorithm, is proposed in this study. When this algorithm was applied in constructing computer-generated holograms, the out-of-focus image crosstalk was effectively reduced, and the image quality was greatly enhanced. In this study, the researchers encrypted each multi-depth or multi-view random phase sub-image with the phase-locked key to generate multi-channel encryption phase information. During the reconstruction, the switch of the phase-locked key of the sub-image was found to achieve different image reconstruction effects with different views or depths. This algorithm proved to substantially reduce the out-of-focus image crosstalk and to enhance the reconstruction quality of the original computer holography without concerning the mutual interference among the information of each view for multi-view and multi-depth holograms.

Crosstalk Reduction in Voxels for a See-Through Holographic Waveguide by Using Integral Imaging with Compensated Elemental Images

The representation of three-dimensional volumetric pixels, voxels, is an important issue for the near-to-eye displays (NEDs) to solve the vergence-accommodation conflict problem. Although the holographic waveguides using holographic optical element (HOE) couplers are promising technologies for NEDs with the ultra-thin structure and high transparency, most of them have presented only a single and fixed depth plane. In this paper, we analyze the imaging characteristics of holographic waveguides, particularly to represent the arbitrary voxels and investigate the voxel duplication problem arising from the non-collimated light from the voxels. In order to prevent the image crosstalk arising from the voxel duplication, we propose an adjustment method for the emission angle profile of voxels by using the integral imaging technique. In the proposed method, the sub-regions of elemental images, which correspond to the duplicated voxels, are masked in order to optimize the emission angle of integrated voxels. In the experimental verification, a see-through integral imaging system, based on the organic light-emitting diode display and a holographic waveguide with the thickness of 5 mm, was constructed. The fabricated HOE in the waveguide showed high diffraction efficiency of 72.8 %, 76.6%, and 72.5 % for 460 nm, 532 nm, and 640 nm lasers, respectively. By applying the masked elemental images, the proposed method resulted in a reduced crosstalk in the observed voxels by 2.35 times. The full-color experimental results of see-through holographic waveguide with integral imaging are provided, whereby the observed 3D images are presented clearly without the ghost images due to the voxel duplication problem.

Holographic Sampling Display Based on Metagratings.

SummaryGlasses-free three-dimensional (3D) display is considered as a potential disruptive technology for display. The issue of visual fatigue, mainly caused by the inaccurate phase reconstruction in terms of image crosstalk, as well as vergence and accommodation conflict, is the critical obstacle that hinders the real applications of glasses-free 3D display. Here we propose a glasses-free 3D display by adopting metagratings for the pixelated phase modulation to form converged viewpoints. When the viewpoints are closely arranged, the holographic sampling 3D display can approximate a continuous light field. We demonstrate a video rate full-color 3D display prototype without visual fatigue under an LED white light illumination. The metagratings-based holographic sampling 3D display has a thin form factor and is compatible with traditional flat panel and thus has the potential to be used in portable electronics, window display, exhibition display, 3D TV, as well as tabletop display.

3-D image Crosstalk Reduction by Controlling the Width of the Electrode in a Liquid Lenticular Lens

In this paper, a liquid lenticular lens with correct focal length was designed by controlling the width of the electrode and analyzing the microfluidic phenomena at boundary between oil and salted water in the liquid lenticular lens. A liquid lenticular lens that has inaccurate focal length results in serious crosstalk and three-dimensional (3-D) image distortion. Therefore, to reduce the crosstalk, the liquid lenticular lens should be fabricated in such a way that the image plane of the LCD is at the focal plane of the lens. To do so, the width of the electrode was adjusted and saturation angle between two liquids and the sidewall of the chamber was measured. The optimum width of the electrode was derived by applying the saturation angle and a final sample having a short focal length was fabricated. When the width of the electrode was optimized, the crosstalk was measured at 21.95% and the value was 10% less than when not being optimized. Also, the viewing angle was increased up to 45°. As a result, this crosstalk reduction led to 3-D image enhancement.

Visible and Near‐Infrared Imaging with Nonfullerene‐Based Photodetectors

AbstractThe solution‐processed organic photodetectors underpin an emerging technology with inherent implications in the biological sensors and imaging displays. Conventional organic photodiodes, the core element of an organic photodetector, rely mainly on fullerene‐based acceptors, which in combination with high and middle bandgap donors, limit the spectral photosensitivity to the visible range. Even in the case of low bandgap polymers the oscillator strength and thus the extinction coefficient are usually limited in the NIR due to the nature of molecular orbital hybridization. Instead, it is showed that pairing prototypical poly(3‐hexylthiophene) (P3HT) with rhodanine‐benzothiadiazole‐coupled indacenodithiophene (IDTBR), a nonfullerene electron acceptor absorbing beyond 750 nm, as the photoactive material of a simple photodiode results in a highly efficient organic photodetector with a record responsivity of 0.42 A W−1 and external quantum efficiency (EQE) of 69% in the NIR (755 nm). Nonfullerene‐based photodiodes are processed on amorphous silicon active matrix backplanes to realize large area flat panel photodetector imagers able to detect objects under visible and NIR light conditions with an exceptional combination of responsivity, dynamic response and image crosstalk.

Bias-variance tradeoff in anticorrelated noise reduction for spectral CT.

In spectral CT, basis material decomposition is commonly used to generate a set of basis images showing the material composition at each point in the field of view. The noise in these images typically contains anticorrelations between the different basis images, which leads to increased noise in each basis image. These anticorrelations can be removed by changing the basis functions used in the material decomposition, but the resulting basis images can then no longer be used for quantitative measurements. Recent studies have demonstrated that reconstruction methods which take the anticorrelations into account give reduced noise in the reconstructed image. The purpose of this work is to analyze an analytically solvable denoising model problem and investigate its effect on the noise level and bias in the image as a function of spatial frequency. A denoising problem with a quadratic regularization term is studied as a mathematically tractable model for such a reconstruction method. An analytic formula for the resulting image in the spatial frequency domain is presented, and this formula is applied to a simple mathematical phantom consisting of an iodinated contrast agent insert embedded in soft tissue. We study the effect of the denoising on the image in terms of its transfer function and the visual appearance, the noise power spectrum and the Fourier component correlation coefficient of the resulting image, and compare the result to a denoising problem which does not model the anticorrelations in the image. Including the anticorrelations in the noise model of the denoising method gives 3-40% lower noise standard deviation in the soft-tissue image while leaving the iodine standard deviation nearly unchanged (0-1% difference). It also gives a sharper edge-spread function. The studied denoising method preserves the noise level and the anticorrelated structure at low spatial frequencies but suppresses the noise and removes the anticorrelations at higher spatial frequencies. Cross-talk between images gives rise to artifacts at high spatial frequencies. Modeling anticorrelations in a denoising problem can decrease the noise level in the basis images by removing anticorrelations at high spatial frequencies while leaving low spatial frequencies unchanged. In this way, basis image cross-talk does not lead to low spatial frequency bias but it may cause artifacts at edges in the image. This theoretical insight will be useful for researchers analyzing and designing reconstruction algorithms for spectral CT.

Reduction of optical aberration induced by refraction of light in a parallax barrier based autostereoscopic 3D display

We investigate the optical aberration effects caused by light refraction in a parallax barrier (PB) based autostereoscopic 3D display to reduce image crosstalk and to avoid distortion of optical properties designed such as optimum viewing distance (OVD). We compare three different structures of the parallax barriers by numerical simulation and experiment, two of which use glass substrates for transform-free PB patterns, while the other one assumes no use of such substrates but a set of thin PB slits in free space. For cases of using PB patterned glass substrate, we consider two different orientations of a PB glass substrate inserted between a display panel and a viewing zone, distinguishable by optical refraction that can occur either after or before PB patterned slits. For improved image quality, we suggest use of the glass substrate with the PB pattern facing the viewing zone, which is installed to allow an air gap between the display panel and PB. It is revealed that this PB structure that can also hold a benefit of rigidity of the slit pattern, does not suffer from a significantly curved feature of the OVD line or alteration of the OVD values from the designed one, thus offering reduced crosstalk. The relevant discussion is provided with the experimental measurement and the simulation results on the optical properties.

Multiplexed fluorescence mediated tomography with temporal and spectral data

We recently developed an algorithm for multiplexed fluorescence tomographic imaging of at least four fluorophores concurrently in the red and near-infrared wavelength region by jointly using spectral and temporal data. We report the design of a fluorescence tomography instrument that acquires spectral and temporal data, and validate its use in tissue-mimicking phantoms with four embedded fluorescent targets with highly overlapped spectral signatures. Critically, this requires measurement or computation of extended fluorophore signature libraries, which capture the variability in the measured signal due to the unknown position of the targets in the media. We demonstrate that we can demix and tomographically image all four fluorophores with zero image cross-talk, and 1 mm or better spatial resolution.

Diffraction effects incorporated design of a parallax barrier for a high-density multi-view autostereoscopic 3D display.

We present optical characteristics of view image provided by a high-density multi-view autostereoscopic 3D display (HD-MVA3D) with a parallax barrier (PB). Diffraction effects that become of great importance in such a display system that uses a PB, are considered in an one-dimensional model of the 3D display, in which the numerical simulation of light from display panel pixels through PB slits to viewing zone is performed. The simulation results are then compared to the corresponding experimental measurements with discussion. We demonstrate that, as a main parameter for view image quality evaluation, the Fresnel number can be used to determine the PB slit aperture for the best performance of the display system. It is revealed that a set of the display parameters, which gives the Fresnel number of ∼ 0.7 offers maximized brightness of the view images while that corresponding to the Fresnel number of 0.4 ∼ 0.5 offers minimized image crosstalk. The compromise between the brightness and crosstalk enables optimization of the relative magnitude of the brightness to the crosstalk and lead to the choice of display parameter set for the HD-MVA3D with a PB, which satisfies the condition where the Fresnel number lies between 0.4 and 0.7.

Optical effects of anti-glare films on a dual-view display

The effects of different anti-glare films on an 8-inch dual-view display were investigated. To quantify the display performance, the image sharpness, speckle, and crosstalk were evaluated. The image sharpness and sparkle were first measured, and the obtained values were compared with the results of a jury appraisal for devising acceptance levels. For image sparkle, it was found that the standard deviation for the individual pixel luminance must be less than 40 to be acceptable to the user. Finally, it was found that the crosstalk of the display needs to be less than 0.5 to be unnoticeable and less than 1.0 to be acceptable.

Image crosstalk correction method of the infrared multispectral camera

There are two bands in the wavelength of 1. 55- 2. 35 μm region for the infrared multispectral camera. Due to the detectors being located on the same focal plane assembly and the design of the readout circuits,one band was found to have crosstalk from other band. Firstly,the crosstalk phenomenon in the infrared multispectral camera image was described and the mechanism of crosstalk phenomenon was investigated. Secondly,based on the aspects of the inner structure of the Hg Cd Te detector's focal plane array and some important parameters of the detector,it was found that light is reflected and transported by multiple reflections in the focal plane area,which was mechanism of optical and electrical crosstalk phenomenon. Meanwhile,the readout circuits' inaccurate design could also lead to crosstalk phenomenon. Mathematical model was built based on crosstalk phenomenon. The research shows that the crosstalk phenomenon( negative / positive pulse) of B10 is relevant to the step( ascending / descending edge) of B11. At last,the crosstalk math model is validated and relevant correction algorithm is developed.

Interpolating vertical parallax for an autostereoscopic three-dimensional projector array

We present a technique for achieving tracked vertical parallax for multiple users using a variety of autostereoscopic projector array setups, including front- and rear-projection and curved display surfaces. This hybrid parallax approach allows for immediate horizontal parallax as viewers move left and right and tracked parallax as they move up and down, allowing cues such as three-dimensional (3-D) perspective and eye contact to be conveyed faithfully. We use a low-cost RGB-depth sensor to simultaneously track multiple viewer head positions in 3-D space, and we interactively update the imagery sent to the array so that imagery directed to each viewer appears from a consistent and correct vertical perspective. Unlike previous work, we do not assume that the imagery sent to each projector in the array is rendered from a single vertical perspective. This lets us apply hybrid parallax to displays where a single projector forms parts of multiple viewers’ imagery. Thus, each individual projected image is rendered with multiple centers of projection, and might show an object from above on the left and from below on the right. We demonstrate this technique using a dense horizontal array of pico-projectors aimed into an anisotropic vertical diffusion screen, yielding 1.5 deg angular resolution over 110 deg field of view. To create a seamless viewing experience for multiple viewers, we smoothly interpolate the set of viewer heights and distances on a per-vertex basis across the array’s field of view, reducing image distortion, cross talk, and artifacts from tracking errors.

Elimination of motion, pulsatile flow and cross-talk artifacts using blade sequences in lumbar spine MR imaging

The purpose of this study is to evaluate the ability of T2 turbo spin echo (TSE) axial and sagittal BLADE sequences in reducing or even eliminating motion, pulsatile flow and cross-talk artifacts in lumbar spine MRI examinations. Forty four patients, who had routinely undergone a lumbar spine examination, participated in the study. The following pairs of sequences with and without BLADE were compared: a) T2 TSE Sagittal (SAG) in thirty two cases, and b) T2 TSE Axial (AX) also in thirty two cases. Both quantitative and qualitative analyses were performed based on measurements in different normal anatomical structures and examination of seven characteristics, respectively. The qualitative analysis was performed by experienced radiologists. Also, the presence of image motion, pulsatile flow and cross-talk artifacts was evaluated. Based on the results of the qualitative analysis for the different sequences and anatomical structures, the BLADE sequences were found to be significantly superior to the conventional ones in all the cases. The BLADE sequences eliminated the motion artifacts in all the cases. In our results, it was found that in the examined sequences (sagittal and axial) the differences between the BLADE and conventional sequences regarding the elimination of motion, pulsatile flow and cross-talk artifacts were statistically significant. In all the comparisons, the T2 TSE BLADE sequences were significantly superior to the corresponding conventional sequences regarding the classification of their image quality. In conclusion, this technique appears to be capable of potentially eliminating motion, pulsatile flow and cross-talk artifacts in lumbar spine MR images and producing high quality images in collaborative and non-collaborative patients.

分时驱动式LED显示屏图像串扰的解决方法

The technology of time-sharing driver type LED has become very mature,but parasitic element will be produced in the circuit board level during the operation of the high frequency hardware circuit,which leads to picture crosstalk.The reasons of the parasitic capacitance in the actual circuit are analysed,then the voltage regulator circuit is adopted to eliminate the inter-row parasitic capacitance,and column driver circuit with two state gate output is designed based on FPGA.The experimental result shows that the method proposed can eliminate the image crosstalk phenomenon completely compared with the traditional time-sharing driver type LED.

Optical structure for a three-dimensional liquid-crystal cell using a wide-band and wide-view half-wave retarder

In order to improve the image crosstalk for a film patterned retarder (FPR) of a linear polarizer type in a stereoscopic three dimensional (3D) display, we propose an optical structure with wideband and wide viewing angle characteristics and using only two half-wave retarders. This proposed half-wave retarder of the FPR 3D cell consists of a λ/2 biaxial film and a patterned λ/2 A-film. We calculated the phase retardation and confirmed the polarization states of the light passing through each film on the Poincare over all visible wavelengths by using the Stokes vector and the Muller matrix method. Then, we optimized the optical parameters of the two retardation films in the oblique direction by using the parameter space method as a function of the optical axis and the NZ parameter of the biaxial λ/2 film. Consequently, we verified that the left 3D crosstalk of the proposed FPR 3D cell could be improved by about 91.87% in the horizontal viewing direction and 97.22% in the vertical viewing direction. The right 3D crosstalk could almost maintain the crosstalk value of the conventional structure.

Creating a static stereoscopic latent image using photoaligned liquid crystal polymers

A static stereoscopic latent image (SSLI) created using photoaligned liquid crystal polymers is introduced. The image crosstalk and contrast are theoretically analyzed by adopting the Jones matrix method. The SSLI does not show any information for the naked eye, but displays a stereoscopic image using polarization spectacles. The image has three domains with even retardances but different optical axes directions with an angular separation of 45 deg. The two-eye view contrast is 0.6433 and the crosstalk is nearly zero, which agree with the theoretical results. This image is applicable to document security and information presentation, among others.

Bidirectionally pumped Cr^4+:YAG crystal fiber light source for optical coherence tomography

A broadband Cr4+:YAG double-clad crystal fiber light source with a collimated output power of 3.15mW was demonstrated by using a bidirectional pump scheme. The bidirectional pump scheme increased the pumping efficiency and reduced the thermal problem along the fiber. Good agreement on the output power of the broadband fluorescence was achieved between experiment and theory, which showed a peak net gain coefficient of 0.03cm−1 at the center wavelength near 1380nm. The 3dB bandwidth of 222nm with a Gaussian-like spectrum makes it eminently suitable for broadband interferometric technique to have low image cross talk. The calculated interference signal shows a 3dB width of 3.62μm with a cross talk smaller than −24dB for adjacent axial image pixels.

Autostereoscopic display based on multi-layer lenticular lens

An autostereoscopic display based on a multi-layer lenticular lens was proposed. The autostereoscopic display is composed of a flat panel display and a multi-layer lenticular lens sheet, which includes a traditional single lenticular lens and an additional transparent layer. The focal length of the multi-layer lenticular lens can be changed by choosing the refractive index of the additional transparent layer to adjust the stereoscopic depth, and it is an easier and much more flexible way than changing lenticular lens's curvature radius. A 22-in. 9-view autostereoscopic display prototype was developed. The image crosstalk of the prototype is very small and it has good presentation to several viewers without wearing eyeglasses.