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Time filter

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Camas, WA, United States

Van Beek P.,Sharp Labs of America | Yang J.,University of Illinois at Chicago | Yamamotoc S.,Sharp Corporation | Ueda Y.,Sharp Corporation
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

In this paper, we investigate the use of the non-local means (NLM) denoising approach in the context of image deblurring and restoration. We propose a novel deblurring approach that utilizes a non-local regularization constraint. Our interest in the NLM principle is its potential to suppress noise while effectively preserving edges and texture detail. Our approach leads to an iterative cost function minimization algorithm, similar to common deblurring methods, but incorporating update terms due to the non-local regularization constraint. The dataadaptive noise suppression weights in the regularization term are updated and improved at each iteration, based on the partially denoised and deblurred result. We compare our proposed algorithm to conventional deblurring methods, including deblurring with total variation (TV) regularization. We also compare our algorithm to combinations of the NLM-based filter followed by conventional deblurring methods. Our initial experimental results demonstrate that the use of NLM-based filtering and regularization seems beneficial in the context of image deblurring, reducing the risk of over-smoothing or suppression of texture detail, while suppressing noise. Furthermore, the proposed deblurring algorithm with non-local regularization outperforms other methods, such as deblurring with TV regularization or separate NLM-based denoising followed by deblurring. © 2010 SPIE. Source


Seo H.-J.,Sharp Labs of America | Milanfar P.,University of California at Santa Cruz
Eurasip Journal on Advances in Signal Processing | Year: 2012

A practical problem addressed recently in computational photography is that of producing a good picture of a poorly lit scene. The consensus approach for solving this problem involves capturing two images and merging them. In particular, using a flash produces one (typically high signal-to-noise ratio [SNR]) image and turning off the flash produces a second (typically low SNR) image. In this article, we present a novel approach for merging two such images. Our method is a generalization of the guided filter approach of He et al., significantly improving its performance. In particular, we analyze the spectral behavior of the guided filter kernel using a matrix formulation, and introduce a novel iterative application of the guided filter. These iterations consist of two parts: a nonlinear anisotropic diffusion of the noisier image, and a nonlinear reaction-diffusion (residual) iteration of the less noisy one. The results of these two processes are combined in an unsupervised manner. We demonstrate that the proposed approach outperforms state-of-the-art methods for both flash/no-flash denoising, and deblurring. © 2012 Seo and Milanfar. Source


Ma Z.,New York University | Segall A.,Sharp Labs of America
Proceedings - International Conference on Image Processing, ICIP | Year: 2011

In this paper, we propose a novel hybrid frame buffer compression algorithm to reduce the memory bandwidth for low-power video coding. In our work, we first decompose the full-resolution image into low resolution (LR) and high resolution (HR) components. We then calculate the HR residual by taking the difference between original HR pixel and an estimate derived from surrounding LR pixels. Finally, we use absolute moment block truncation coding to quantize and compress the LR pixel and HR residual data so as to reduce the memory bandwidth. We integrate our approach into the JCT-VC reference software for High Efficiency Video Coding (HEVC). Results show negligible impact on coding efficiency with significant memory bandwidth reduction. Specifically, we observe a bit rate increase of 0.38% and 1% with 21% and 31% memory bandwidth reduction, respectively. © 2011 IEEE. Source


Jagodic R.,University of Illinois at Chicago | Renambot L.,University of Illinois at Chicago | Johnson A.,University of Illinois at Chicago | Leigh J.,University of Illinois at Chicago | Deshpande S.,Sharp Labs of America
Future Generation Computer Systems | Year: 2011

As the amount and the resolution of collected scientific data increase, scientists are realizing the potential benefits that large high-resolution displays can have in assimilating this incoming data. Often this data has to be processed on powerful remote computing and storage resources, converted to high-resolution digital media and yet visualized on a local tiled-display. This is the basic premise behind the OptIPuter model. While the streaming middleware to enable this kind of work exists and the optical networking infrastructure is becoming more widely available, enabling multi-user interaction in such environments is still a challenge. In this paper, we present an interaction system we developed to support collaborative work on large high-resolution displays using multiple interaction devices and scalable, distributed user interface widgets. This system allows multiple users to simultaneously interact with local or remote data, media and applications, through a variety of physical interaction devices on large high-resolution displays. Finally, we present our experiences with using the system over the past two years. Most importantly, having an actual working system based on the OptIPuter model allows us to focus our research efforts to better understand how to make such high-resolution environments more user-friendly and usable in true real-world collaborative scenarios as opposed to constrained laboratory settings. © 2010 Elsevier B.V. All rights reserved. Source


Li F.,Aptina | Pelz J.B.,Rochester Institute of Technology | Daly S.J.,Sharp Labs of America
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

Smooth pursuit eye movements align the retina with moving targets, ideally stabilizing the retinal image. At a steadystate, eye movements typically reach an approximately constant velocity which depends on, and is usually lower than the target velocity. Experiment 1 investigated the effect of target size and velocity on smooth pursuit induced by realistic images (color photographs of an apple and flower subtending 2° and 17°, respectively), in comparison with a small dot subtending a fraction of a degree. The extended stimuli were found to enhance smooth pursuit gain. Experiment 2 examined the absolute velocity limit of smooth pursuit elicited by the small dot and the effect of the extended targets on the velocity limit. The eye velocity for tracking the dot was found to be saturated at about 63 deg/sec while the saturation velocity occurred at higher velocities for the extended images. The difference in gain due to target size was significant between dot and the two extended stimuli, while no statistical difference exists between an apple and flower stimuli of wider angular extent. Detailed knowledge of the smooth pursuit eye movements is important for several areas of electronic imaging, in particular, assessing perceived motion blur of displayed objects. © 2010 Copyright SPIE - The International Society for Optical Engineering. Source

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