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98 results on '"Balram, Nikhil"'

5. Noncausal predictive image codec

Author

Balram, Nikhil and Moura, Jose M.F.

Subjects
Image processing -- Digital techniques, Codecs -- Innovations, Image coding -- Equipment and supplies, Business, Computers, Electronics, Electronics and electrical industries
Abstract

A noncausal predictive image codec based on a noncausal prediction model alongwith vector quantization is more efficient in image compression than conventional causal predictors. An equivalent unilateral transformation of the noncausal model provides the advantages of recursive processing. This does not affect the optimality of the noncausal model. The causal predictor produces reconstructed images with high amount of streaking, while those produced by the noncausal predictor does not contain streaking. The codec gives high-quality compressed images at low bit rates.

Published
1996

6. Noncausal Gauss Markov random fields: parameter structure and estimation

Author

Balram, Nikhil and Moura, Jose M.F.

Subjects
Gaussian processes -- Research, Information theory -- Research, Maximum likelihood estimates (Statistics) -- Research
Abstract

The parameter structure of noncausal homogeneous Gauss Markov random fields (GMRF) defined on finite lattices is studied. For first-order (nearest neighbor) and a special class of second-order fields, we provide a complete characterization of the parameter space and a fast implementation of the maximum likelihood (ML) estimator of the field parameters. For general higher order fields, tight bounds for the parameter space are presented and an efficient procedure for ML estimation is described. Experimental results illustrate the application of the approach presented and the viability of the present method in fitting noncausal models to 2-D data.

Published
1993

12. Using Temporal Fill Factor to Reduce Frame Reconstruction Rates

Author

Larimer, James, Balram, Nikhil, Gille, Jennifer, and Luszcz, Jeffery

Subjects
Electronics And Electrical Engineering
Abstract

The newer active matrix display technologies such as TFT-LCD, DMD, PDP maintain their pixel values through the entire frame time, presenting a 100% temporal fill factor, in contrast to the duty cycle produced by the phosphor impulse response of the CRT. This sample-and-hold characteristic can be exploited to lower the displayed frame rate without affecting visual quality. The lower frame rate results in significantly lower transmission bandwidth, power, and cost.

Published
1997

20. 31‐1: Distinguished Paper: Measurement and Categorization of Alternate Subpixel Layout Near‐Eye Display Systems.

Author

Hoffman, David M., McKenzie, Chris, Koprowski, Brion, Iqbal, Asif, and Balram, Nikhil

Subjects
DISPLAY systems, INFORMATION display systems, HEAD-mounted displays, MEASUREMENT
Abstract

We analyzed displays with alternate subpixel layouts to assess the effective detail size that they can reproduce. The measurements can then be used to classify the display to an appropriate XR system tier. Responsive application design can then tailor content for the best possible experience on each system tier. [ABSTRACT FROM AUTHOR]

Published
2019
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26. 3‐2: Distinguished Paper: An 18 Megapixel 4.3″ 1443 ppi 120 Hz OLED Display for Wide Field of View High Acuity Head Mounted Displays.

Author

Vieri, Carlin, Lee, Grace, Balram, Nikhil, Jung, Sang Hoon, Yang, Joon Young, Yoon, Soo Young, and Kang, In Byeong

Subjects
ORGANIC light emitting diodes, LED displays, HEAD-mounted displays
Abstract

We developed and fabricated the world's highest resolution (18 megapixel, 1443 ppi) OLED on glass display panel. The design uses a white OLED with color filter structure for high density pixelization and an n‐type LTPS backplane for faster response time than mobile phone displays. A custom high bandwidth driver IC was fabricated. We developed a foveated pixel pipeline appropriate for VR and AR applications, especially mobile systems. [ABSTRACT FROM AUTHOR]

Published
2018
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27. Revelation and addressing of accommodation shifts in microlens array-based 3D near-eye light field displays

Author

Qin, Zong, Wu, Jui-Yi, Chou, Ping-Yen, Chen, Yu-Ting, Huang, Cheng-Ting, Balram, Nikhil, and Huang, Yi-Pai

Abstract

In a 3D near-eye light field display using microlens array-based integral imaging, the accommodation response is presumed to exactly coincide with the reconstructed depth plane (RDP) which, however, has been little examined. By employing a highly accurate image formation model to analyze retinal images, the accommodation response is revealed to significantly shift towards the central depth plane (CDP) because of defocusing. The shift is quantitatively characterized for various CDPs and RDPs with a preliminary verifying experiment to provide content producers an approach to address the accommodation shift to fully mitigate the vergence-accommodation conflict.

Published
2020

28. 31‐1: Distinguished Paper:Measurement and Categorization of Alternate Subpixel Layout Near‐Eye Display Systems

Author

Hoffman, David M., McKenzie, Chris, Koprowski, Brion, Iqbal, Asif, and Balram, Nikhil

Abstract

We analyzed displays with alternate subpixel layouts to assess the effective detail size that they can reproduce. The measurements can then be used to classify the display to an appropriate XR system tier. Responsive application design can then tailor content for the best possible experience on each system tier.

Published
2019
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29. 73‐4: Distinguished Paper:Image Formation Modeling and Analysis of Near‐Eye Light Field Displays

Author

Qin, Zong, Chou, Ping-Yen, Chen, Yu-Ting, Wu, Jui-Yi, Lin, Ting-Ru, Lin, Ting-Hsuan, Balram, Nikhil, and Huang, Yi-Pai

Abstract

The image formation of microlens array‐based near‐eye light field displays is modeled with near‐perfect accuracy by incorporating diffraction, ray aberration, defocusing, and pixel sampling. Based on this model, algorithms and hardware parameters are suggested for resolution optimization, and the resolution variations with FOV and image depth are analyzed.

Published
2019
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30. 31‐4: Invited Paper:3D Eyebox in Augmented and Virtual Reality Optics

Author

Cakmakci, Ozan, Hoffman, David M., and Balram, Nikhil

Abstract

The eyebox volume is a key design parameter in the optical design of augmented and virtual reality optics. The extent of the eyebox volume determines the experience of a user in seeing the entire virtual magnified image. Furthermore, a 3D description of eyebox facilitates the design of augmented and virtual reality products for a population of users. We define 3D eyebox and discuss visualization approaches to communicate it within interdisciplinary product design groups focused on research and development of augmented and virtual reality optics.

Published
2019
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37. 3‐2: Distinguished Paper:An 18 Megapixel 4.3″ 1443 ppi 120 Hz OLED Display for Wide Field of View High Acuity Head Mounted Displays

Author

Vieri, Carlin, Lee, Grace, Balram, Nikhil, Jung, Sang Hoon, Yang, Joon Young, Yoon, Soo Young, and Kang, In Byeong

Abstract

We developed and fabricated the world's highest resolution (18 megapixel, 1443 ppi) OLED on glass display panel. The design uses a white OLED with color filter structure for high density pixelization and an n‐type LTPS backplane for faster response time than mobile phone displays. A custom high bandwidth driver IC was fabricated. We developed a foveated pixel pipeline appropriate for VR and AR applications, especially mobile systems.

Published
2018
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47. 24.1: Invited Paper: Design Principles for Light Field Image Capture and Display.

Author

Berkner, Kathrin, Toši, Ivana, Wu, Wanmin, Meng, Lingfei, Bedard, Noah, and Balram, Nikhil

Subjects
THREE-dimensional display systems, INFORMATION display systems, THREE-dimensional imaging, IMAGING systems, IMAGE processing
Abstract

Light field capture and display technologies have been rapidly emerging in the past decade. The high dimensional design space of light field systems, however, imposes new challenges for end to end system design and evaluation. We discuss design principles for task specific light field camera systems and outline how such principles can be applied to or need to be modified for the design of personal light field displays. [ABSTRACT FROM AUTHOR]

Published
2015
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50. Personal Near-to-Eye Light-Field Displays.

Author

Wanmin Wu, Berkner, Kathrin, Tošić, Ivana, and Balram, Nikhil

Subjects
THREE-dimensional display systems, DISPLAY systems, VIRTUAL reality, AUGMENTED reality, WEARABLE technology
Abstract

The article discusses aspects of the near-to-eye (NTE) light-field three dimensional (3D) display system. Topics include the NTE component of a Mobile Information Gateway (MIG), the two classification of NTE displays, which are the virtual-reality (VR) and augmented-reality (AR) displays, and the main components of a personal light-field-display system. Also mentioned are the process of achieving true 3-D projection in a wearable display.

Published
2014
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