Photochromic diarylethene for reversible holographic recording

A novel photochromic, diarylethene with 2,5-dihydrothiophene bridging unit la was synthesized, and the photochromic properties of 1 were also investigated. It showed that I exhibited excellent ring-open and ring-closed photochromism with UV/vis light irradiation. Holographic recording was measured by employing the thin film of PMMA-diarylethene 1 as recording media. It showed that six different images were recorded in the same place on the sample with the dimension of 64 mu m x 42 mu m by the intersecting of the object beam and a reference beam with an intensity of 15 mW/cm(2), and the stored information was readout by the attenuated reference beam with an intensity of 0.5 mW/cm(2). In addition, preliminary investigations showed that the material was thermally stable and fatigue resistant. (C) 2007 Elsevier B.V. All rights reserved.

Photochromic fulgide for holographic recording

(N-4'-methoxy-2-methyl-5-phenyl)-3-pyrryl-ethylidene (isopropylidene) succinic anhydride fulgide, doped in PMMA matrix, exhibits photochromic behavior. The fatigue resistance experiment shows no photodegradation is detected after more than 450 writing-erasing cycles. Study of fulgide material for holographic recording media shows the optimal exposure and the diffraction efficiency is 1047 mJ/cm(2) and 2.26%, respectively, with 10 mum thickness polymer film. Holographic grating with 1680 lines/mm at writing angle theta = 30degrees is also obtained. (C) 2004 Elsevier B.V. All rights reserved.

Dual-wavelength photochromic fulgides for parallel recording memory

Two photochromic fulgides, 2-{2-[4-(N,N-dimethylnilino)-5-methyl-4-oxazoly]}ethylidene-4-(1-methylethylidene) tetrahydrofuran-2,5-dione (A) and 3-(1,2-dimethyl-5-phenyl-3-pyrolloethylidene)-4-(1-methylethylidene)tetrahydrofuran-2,5-dione (B), doped in PMMA as candidates of dual-wavelength optical memory for parallel recording has been investigated. With 488 nm-laser and 650 nm-laser, both "cross" and "star" images are recorded on the fulgides-PMMA film and read out clearly, respectively. Crosstalk between two fulgides in PMMA matrix and nondestructive readout has also been explored. The results show that no significant cross-talk is detected between them, and nondestructive readout is up to 201 times. (C) 2005 Elsevier B.V. All rights reserved.

Polarization multiplexing holographic optical recording of a new photochromic diarylethene

A new unsymmetrical photochromic diarylethene 1a is synthesized, and the photochromic properties of it are also investigated. The compound exhibits good photochromism with UV/ visible light irradiation. Compound 1a in polymethyl methacrylate ( PMMA ) film changes color upon 313- nm light irradiation from colorless to blue, in which the absorption maximum is observed at 587 nm. Photon- mode polarization multiplexing holographic optical recording is performed successfully using this compound as a recording medium. In the diarylethene 1b/ PMMA film, polarization multiplexing hologram recording and retrieval, and a combination with the angular multiplexing scheme, are demonstrated systematically. The results indicate that recording capacity can be significantly improved with the combined method of polarization and angular multiplexing holographic recording. (C) 2008 Society of Photo- Optical Instrumentation Engineers.

A new half-flash architecture for high speed video ADC

In this paper a new half-flash architecture for high speed video ADC is presented. Based on a high speed single-way analog switch circuit, this architecture effectively reduces the number of elements. At the same lime no sacrifice of speed is needed compared with the normal half-flash structure.

Non-goal scene analysis for soccer video

The broadcast soccer video is usually recorded by one main camera, which is constantly gazing somewhere of playfield where a highlight event is happening. So the camera parameters and their variety have close relationship with semantic information of soccer video, and much interest has been caught in camera calibration for soccer video. The previous calibration methods either deal with goal scene, or have strict calibration conditions and high complexity. So, it does not properly handle the non-goal scene such as midfield or center-forward scene. In this paper, based on a new soccer field model, a field symbol extraction algorithm is proposed to extract the calibration information. Then a two-stage calibration approach is developed which can calibrate camera not only for goal scene but also for non-goal scene. The preliminary experimental results demonstrate its robustness and accuracy. (c) 2010 Elsevier B.V. All rights reserved.

A Video Quality Assessment Metric Based on Human Visual System

It is important for practical application to design an effective and efficient metric for video quality. The most reliable way is by subjective evaluation. Thus, to design an objective metric by simulating human visual system (HVS) is quite reasonable and available. In this paper, the video quality assessment metric based on visual perception is proposed. Three-dimensional wavelet is utilized to decompose video and then extract features to mimic the multichannel structure of HVS. Spatio-temporal contrast sensitivity function (S-T CSF) is employed to weight coefficient obtained by three-dimensional wavelet to simulate nonlinearity feature of the human eyes. Perceptual threshold is exploited to obtain visual sensitive coefficients after S-T CSF filtered. Visual sensitive coefficients are normalized representation and then visual sensitive errors are calculated between reference and distorted video. Finally, temporal perceptual mechanism is applied to count values of video quality for reducing computational cost. Experimental results prove the proposed method outperforms the most existing methods and is comparable to LHS and PVQM.

Biologically Inspired Features for Scene Classification in Video Surveillance

Inspired by human visual cognition mechanism, this paper first presents a scene classification method based on an improved standard model feature. Compared with state-of-the-art efforts in scene classification, the newly proposed method is more robust, more selective, and of lower complexity. These advantages are demonstrated by two sets of experiments on both our own database and standard public ones. Furthermore, occlusion and disorder problems in scene classification in video surveillance are also first studied in this paper.

Towards an Example-Based Image Compression Architecture for Video-Conferencing

This paper consists of two major parts. First, we present the outline of a simple approach to very-low bandwidth video-conferencing system relying on an example-based hierarchical image compression scheme. In particular, we discuss the use of example images as a model, the number of required examples, faces as a class of semi-rigid objects, a hierarchical model based on decomposition into different time-scales, and the decomposition of face images into patches of interest. In the second part, we present several algorithms for image processing and animation as well as experimental evaluations. Among the original contributions of this paper is an automatic algorithm for pose estimation and normalization. We also review and compare different algorithms for finding the nearest neighbors in a database for a new input as well as a generalized algorithm for blending patches of interest in order to synthesize new images. Finally, we outline the possible integration of several algorithms to illustrate a simple model-based video-conference system.

Monitoring Activities from Multiple Video Streams: Establishing a Common Coordinate Frame

Passive monitoring of large sites typically requires coordination between multiple cameras, which in turn requires methods for automatically relating events between distributed cameras. This paper tackles the problem of self-calibration of multiple cameras which are very far apart, using feature correspondences to determine the camera geometry. The key problem is finding such correspondences. Since the camera geometry and photometric characteristics vary considerably between images, one cannot use brightness and/or proximity constraints. Instead we apply planar geometric constraints to moving objects in the scene in order to align the scene"s ground plane across multiple views. We do not assume synchronized cameras, and we show that enforcing geometric constraints enables us to align the tracking data in time. Once we have recovered the homography which aligns the planar structure in the scene, we can compute from the homography matrix the 3D position of the plane and the relative camera positions. This in turn enables us to recover a homography matrix which maps the images to an overhead view. We demonstrate this technique in two settings: a controlled lab setting where we test the effects of errors in internal camera calibration, and an uncontrolled, outdoor setting in which the full procedure is applied to external camera calibration and ground plane recovery. In spite of noise in the internal camera parameters and image data, the system successfully recovers both planar structure and relative camera positions in both settings.

Learning object segmentation from video data

This memo describes the initial results of a project to create a self-supervised algorithm for learning object segmentation from video data. Developmental psychology and computational experience have demonstrated that the motion segmentation of objects is a simpler, more primitive process than the detection of object boundaries by static image cues. Therefore, motion information provides a plausible supervision signal for learning the static boundary detection task and for evaluating performance on a test set. A video camera and previously developed background subtraction algorithms can automatically produce a large database of motion-segmented images for minimal cost. The purpose of this work is to use the information in such a database to learn how to detect the object boundaries in novel images using static information, such as color, texture, and shape. This work was funded in part by the Office of Naval Research contract #N00014-00-1-0298, in part by the Singapore-MIT Alliance agreement of 11/6/98, and in part by a National Science Foundation Graduate Student Fellowship.