- Date & Time: Wednesday, June 15, 2011; 12:00 PM
Speaker: Dr. Yue M. Lu, Harvard School of Engineering and Applied Sciences
MERL Host: Petros T. Boufounos Abstract - Before the advent of digital image sensors, photography, for the most part of its history, used film to record light information. In this talk, I will present a new digital image sensor that is reminiscent of photographic film. Each pixel in the sensor has a binary response, giving only a one-bit quantized measurement of the local light intensity.
To analyze its performance, we formulate the binary sensing scheme as a parameter estimation problem based on quantized Poisson statistics. We show that, with a single-photon quantization threshold and large oversampling factors, the Cramer-Rao lower bound of the estimation variance approaches that of an ideal unquantized sensor, that is, as if there were no quantization in the sensor measurements. Furthermore, this theoretical performance bound is shown to be asymptotically achievable by practical image reconstruction algorithms based on maximum likelihood estimators.
Numerical results on both synthetic data and images taken by a prototype sensor verify the theoretical analysis and the effectiveness of the proposed image reconstruction algorithm. They also demonstrate the benefit of using the new binary sensor in applications involving high dynamic range imaging.
Joint work with Feng Yang, Luciano Sbaiz and Martin Vetterli.
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- Date & Time: Tuesday, June 14, 2011; 4:00 PM
Speaker: Tadayoshi Aoyama, Nagoya University
Research Area: Computer Vision
Abstract - First, the concept of "Multi-Locomotion Robot" that has multiple types of locomotion is introduced. The robot is developed to achieve a bipedal walk, a quadruped walk and a brachiation, mimicking locomotion ways of a gorilla. It therefore has higher mobility by selecting a proper locomotion type according to its environment and purpose. I show you some experimental videos with respect to realized motions before now.
Second, I focus on biped walk and talk about detail of bipedal walking. This part proposes a 3-D biped walking algorithm based on Passive Dynamic Autonomous Control (PDAC). The robot dynamics is modeled as an autonomous system of a 3-D inverted pendulum by applying the PDAC concept that is based on the assumption of point contact of the robot foot and the virtual constraint as to robot joints. Due to autonomy, there are two conservative quantities named "PDAC constant", that determine the velocity and direction of the biped walking. We also propose the convergence algorithm to make PDAC constants converge to arbitrary values, so that walking velocity and direction are controllable. Finally, experimental results validate the performance and the energy efficiency of the proposed algorithm.
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- Date: June 8, 2011
Where: IEEE International Symposium on Broadband Multimedia Systems and Broadcasting (BMSB)
MERL Contacts: Jinyun Zhang; Philip V. Orlik
Research Area: Communications
Brief - The paper "Resource Block Embedding: Towards High Throughput Broadband Multimedia Wireless Networks" by Annavajjala, R., Orlik, P.V. and Zhang, J. was presented at the IEEE International Symposium on Broadband Multimedia Systems and Broadcasting (BMSB).
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- Date: June 5, 2011
Where: IEEE International Conference on Communications (ICC)
MERL Contacts: Jinyun Zhang; Philip V. Orlik; Toshiaki Koike-Akino Brief - The papers "Reduced-Rate OFDM Transmission with Statistics-based ICI Mitigation" by Ma, J., Orlik, P., Zhang, J. and Li, G.Y., "Super-Resolution Blind Channel Modeling" by Pun, M.-O., Molisch, A.F., Orlik, P. and Okazaki, A., "Network-Coded Interference Alignment in K-Pair Bidirectional Relaying Channels" by Koike-Akino, T., Pun, M.-O. and Orlik, P., "Non-Coherent Grassmann TCM Design for Physical-Layer Network Coding in Bidirectional MIMO Relaying Systems" by Koike-Akino, T. and Orlik, P. and "Order-Extended Sparse RLS Algorithm for Doubly-Selective MIMO Channel Estimation" by Koike-Akino, T., Molisch, A.F., Annavajjala, R., Orlik, P. and Pun, M.-O. were presented at the IEEE International Conference on Communications (ICC).
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- Date & Time: Friday, June 3, 2011; 11:00 AM
Speaker: Prof. Namrata Vaswani, Iowa State University
MERL Host: Petros T. Boufounos Abstract - In this talk, I will discuss our recent work on Recursive Sparse Recovery (RecSparsRec) and show how it provides novel solutions to two very different problems in dynamic imaging. RecSparsRec refers to recursive approaches to causally recover a time sequence of signals/images from a greatly reduced number of measurements (compared to existing approaches), by utilizing their sparsity.
The motivating application for RecSparsRec is fast recursive dynamic magnetic resonance imaging (MRI) for real-time applications like MRI-guided surgery. MRI is a technique for cross-sectional imaging that acquires Fourier projections of the cross-section to be reconstructed, one-at-a-time. Thus, the ability to accurately reconstruct using fewer measurements directly translates into reduced scan times. This, along with online (causal) and fast (recursive) reconstruction algorithms, can enable real-time imaging of fast changing physiological phenomena, and thus make real-time MRI feasible. Cross-sectional images of the brain, heart, or other organs are known to be wavelet sparse. Our recent work was the first to observe that, in a time sequence, their sparsity pattern changes quite slowly. Using this fact, we were able to reformulate the RecSparsRec problem as one of sparse reconstruction with partially known support. We introduced a simple, but very powerful, approach called!
Modified-CS that achieves provably exact reconstruction (in the noise-free case) and whose error is provably stable over time (in the noisy case), with using much fewer measurements than existing work. Our preliminary experiments indicate that Modified-CS needs roughly 5-times fewer measurements than existing MR scanner technology and 1.5-times fewer than existing research literature.
I will briefly also discuss our ongoing work on the difficult video analysis problem of separating foreground moving objects from a background scene that is itself is changing and dong this in real-time. This can be posed as a recursive robust principal components analysis (PCA) problem in the presence of correlated sparse outliers or equivalently, as a problem of recursive sparse recovery in the presence of very large, but ``low rank" noise (noise with a low rank covariance matrix).
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- Date & Time: Thursday, June 2, 2011; 12:00 PM
Speaker: Ramesh Annavajjala, MERL
MERL Host: Philip V. Orlik Abstract - For orthogonal frequency-division multiplexing (OFDM) based wireless systems, a resource block (RB) in a two-dimensional time-frequency plane is defined as a data block spanned by a number of consecutive OFDM symbols over a number of consecutive subcarriers. Traditionally, RBs contain modulation symbols for data transmission and pilot symbols for channel estimation.
In this talk, I present a novel approach to RB designs for OFDM systems with multiple antennas at the transmitter and the receiver (i.e., MIMO-OFDM). The proposed approach, termed resource block embedding, does not require explicit pilot symbols to estimate the channel at the receiver, and hence reduces the channel estimation overhead significantly. I describe, in detail, the encoding and decoding algorithms for our proposed embedded resource blocks (ERB) for single-user single-antenna transmission, two transmitter antenna Alamouti code, four transmitter antenna stacked Alamouti code, and multi-stream spatial multiplexing. I also outline construction of ERBs for multi-user MIMO systems.
This is a joint work with Phil Orlik and Jin Zhang.
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- Date: May 23, 2011
Where: IEEE Radar Conference (RadarCon)
Research Area: Signal Processing
Brief - The paper "Low Complexity STAP via Subspace Tracking in Compound-Gaussian Environment" by Wang, P., Pun, M.O. and Sahinoglu, Z. was presented at the IEEE Radar Conference (RadarCon).
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- Date: May 23, 2011
Where: IEEE Transactions on Information Theory
MERL Contact: Petros T. Boufounos
Research Area: Computational Sensing
Brief - The article "Sparse Recovery from Combined Fusion Frame Measurements" by Boufounos, P.T., Kutyniok, G. and Rauhut, H. was published in IEEE Transactions on Information Theory.
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- Date: May 22, 2011
Where: IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)
MERL Contact: Petros T. Boufounos Brief - The papers "Compressive Sensing for Over-the-Air Ultrasound" by Boufounos, P.T., "Privacy Preserving Probabilistic Inference with Hidden Markov Models" by Pathak, M., Rane, S., Sun, W. and Raj, B., "Saturation-robust SAR Image Formation" by Wei, D. and Boufounos, P.T. and "Scale-Invariant GLRT in Stochastic Partially Homogeneous Environments" by Wang, P., Sahinoglu, Z., Pun, M.-O., Li, H. and Himed, B. were presented at the IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP).
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- Date: May 15, 2011
Where: IEEE International Symposium on Circuits and Systems (ISCAS)
MERL Contact: Anthony Vetro
Research Area: Digital Video
Brief - The paper "Efficient Dictionary Based Video Coding with Reduced Side Information" by Kang, J.-W., Kuo, C.-C. J., Cohen, R. and Vetro, A. was presented at the IEEE International Symposium on Circuits and Systems (ISCAS).
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- Date: May 15, 2011
Where: IEEE Vehicular Technology Conference (VTC)
Research Area: Communications
Brief - The paper "Performance Evaluation of Cross-Polarized Antenna Selection over 2 GHz Measurement-Based Channel Models" by Nishimoto, H., Taira, A., Kubo, H., Pun, M.O., Annavajjala, R. and Molisch, A.F. was presented at the IEEE Vehicular Technology Conference (VTC).
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- Date: May 12, 2011
Where: CIRP Conference on Modeling of Machining Operations
Research Area: Computer Vision
Brief - The paper "Modeling Cutting Forces for 5-Axis Machining of Sculptured Surfaces" by Boz, Y., Erdim, H. and Lazoglu, I. was presented at the CIRP Conference on Modeling of Machining Operations.
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- Date: May 9, 2011
Where: IEEE International Conference on Robotics and Automation (ICRA)
Research Area: Computer Vision
Brief - The papers "Pose Estimation using Both Points and Lines for Geo-Localization" by Ramalingam, S., Bouaziz, S. and Sturm, P. and "Finding a Needle in a Specular Haystack" by Shroff, N., Taguchi, Y., Tuzel, O., Veeraraghavan, A., Ramalingam, S. and Okuda, H. were presented at the IEEE International Conference on Robotics and Automation (ICRA).
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- Date: May 2, 2011
Where: International Conference on Sampling Theory and Applications (SampTA)
MERL Contact: Petros T. Boufounos
Research Area: Computational Sensing
Brief - The paper "Hierarchical Distributed Scalar Quantization" by Boufounos, P.T. was presented at the International Conference on Sampling Theory and Applications (SampTA).
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- Date: Sunday, May 1, 2011
MERL Contact: Anthony Vetro Brief - Anthony Vetro is Guest Editor for the Special Issue on Distributed Image Processing and Communications of the IEEE Signal Processing Magazine.
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- Date: April 27, 2011
Where: SPIE Defense, Security and Sensing, Algorithms for Synthetic Aperture Radar Imagery
MERL Contacts: Anthony Vetro; Petros T. Boufounos
Research Area: Digital Video
Brief - The paper "Low-Complexity Efficient Raw SAR Data Compression" by Rane, S., Boufounos, P., Vetro, A. and Okada, Y. was presented at SPIE Defense, Security and Sensing, Algorithms for Synthetic Aperture Radar Imagery.
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- Date: April 21, 2011
Where: IEEE Transactions on Wireless Communications
MERL Contacts: Jinyun Zhang; Philip V. Orlik
Research Area: Communications
Brief - The article "Pilot Matrix Design for Estimating Cascaded Channels in Two-Hop MIMO Amplify-and-Forward Relay Systems" by Ma, J., Orlik, P., Zhang, J. and Li, G.Y. was published in IEEE Transactions on Wireless Communications.
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- Date: April 21, 2011
Where: IEEE Transactions on Signal Processing
Research Area: Communications
Brief - The article "Comparative Analysis of Pilot-Assisted Distributed Co-phasing Approaches in Wireless Sensor Networks" by Chaythanya, K.V., Annavajjala, R. and Murthy, C.R. was published in IEEE Transactions on Signal Processing.
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- Date: April 15, 2011
Where: Proceedings of the IEEE
MERL Contact: Anthony Vetro
Research Area: Digital Video
Brief - The article "Overview of the Stereo and Multiview Video Coding Extensions of the H.264/MPEG-4 AVC Standard" by Vetro, A., Wiegand, T. and Sullivan, G. J. was published in Proceedings of the IEEE.
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- Date: April 11, 2011
Where: European Conference on Antennas and Propagation (EuCAP)
MERL Contacts: Bingnan Wang; Koon Hoo Teo; William S. Yerazunis
Research Areas: Applied Physics, Electric Systems
Brief - The paper "Wireless Power Transfer with Metamaterials" by Wang, B., Teo, K.H., Nishino, T., Yerazunis, W., Barnwell, J. and Zhang, J. was presented at the European Conference on Antennas and Propagation (EuCAP).
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- Date: April 10, 2011
Where: Eurographics Workshop on 3D Object Retrieval
Research Area: Computer Vision
Brief - The paper "Shape Retrieval on Non-rigid 3D Watertight Meshes" by Lian, Z., Godil, A., Bustos, B., Daoudi, M., Hermans, J., Kawamura, S., Kurita, Y., Lavoua, G., Nguyen, H.V., Ohbuchi, R., Ohkita, Y., Porikli, F., Reuter, M., Sipiran, I., Smeets, P., Suetens, P., Tabia, H. and Vandermeulen, D. was presented at the Eurographics Workshop on 3D Object Retrieval.
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- Date: April 8, 2011
Where: IEEE Transactions on Pattern Analysis and Machine Intelligence Brief - The articles "Coded Strobing Photography: Compressive Sensing of High-Speed Periodic Events" by Veeraraghavan, A.N., Reddy, D. and Raskar, R. and "Statistical Computations on Grassmann and Stiefel Manifolds for Image and Video-Based Recognition" by Turaga, P., Veeraraghavan, A., Srivastava, A. and Chellappa, R. were published in IEEE Transactions on Pattern Analysis and Machine Intelligence.
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- Date: April 4, 2011
Where: Symposium on Simulation for Architecture and Urban Design (SimAUD)
Research Area: Computer Vision
Brief - The paper "Sensor Placement Tool for Rapid Development of Video Sensor Layouts" by Garaas, T.W. was presented at the Symposium on Simulation for Architecture and Urban Design (SimAUD).
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- Date: Friday, April 1, 2011
MERL Contact: Anthony Vetro Brief - Anthony Vetro is Guest Editor for the Special Issue on 3D Media & Displays of the Proceedings of the IEEE.
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- Date: March 29, 2011
Where: Data Compression Conference (DCC)
MERL Contact: Anthony Vetro
Research Area: Digital Video
Brief - The paper "Robust Learning of 2-D Separable Transforms for Next-Generation Video Coding" by Sezer, O.G., Cohen, R. and Vetro, A. was presented at the Data Compression Conference (DCC).
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