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121 results on '"Zhao, Chumin"'

6. Image quality characterization of near‐eye displays.

Author

Beams, Ryan, Zhao, Chumin, and Badano, Aldo

Subjects
*VIRTUAL reality, *SPATIAL resolution, *EVALUATION methodology, *MEASUREMENT
Abstract

We review the literature and relevant standards related to image quality characterization of medical devices using near‐eye displays (NEDs). First, we discuss the experimental considerations for NED measurements and the methods for aligning the light measuring device (LMD) to the NED. Second, we discuss measurement methods for several critical image quality characteristics, namely luminance, contrast, spatial resolution, geometrical distortion, and spatiotemporal properties including the methods' limitations. These characteristics were selected due to the importance of medical device NED applications. Finally, modeling methods for image quality of NEDs are discussed. Accurate and reproducible evaluation methods for image quality are essential for the safe and effective adoption of augmented and virtual reality NEDs into medical applications. [ABSTRACT FROM AUTHOR]

Published
2024
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8. P‐49: Angular Dependent Point Spread Function Analysis for Virtual Reality Head Mounted Displays.

Author

Beams, Ryan, Johnson, Matthew, Zhao, Chumin, and Varshney, Amitabh

Subjects
TRANSFER functions, SPATIAL resolution, VIRTUAL reality, IMAGE converters, METROLOGY, HEAD-mounted displays
Abstract

We demonstrate a point spread function method for measuring the angular dependence of the spatial resolution of a virtual reality head mounted display. The angular dependence of spatial resolution of the imaging detector was characterized to remove the detector's contribution at each angular location measured on the VR HMD. This method allows measuring the twodimensional spatial resolution and modulation transfer function. [ABSTRACT FROM AUTHOR]

Published
2024
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9. 82‐1: Distinguished Paper: Geometric Distortion on Video See‐Through Head‐Mounted Displays.

Author

Zhao, Chumin and Beams, Ryan

Subjects
VIRTUAL reality, METROLOGY, CALIBRATION, CAMERAS, VIDEOS, HEAD-mounted displays
Abstract

We evaluate the geometric distortion on video see‐through (VST) head‐mounted displays (HMDs) with single‐camera and dualcamera design. We present the experimental setup and metrology for geometric calibration and VST geometric distortion measurement. Physical geometric distortion is compared to the distortion of digital content on a VST HMD. We investigate the impacts of camera misalignment and depth distance on VST geometric distortion with angular‐based distortion correction. [ABSTRACT FROM AUTHOR]

Published
2024
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12. 82‐1: Distinguished Paper:Geometric Distortion on Video See‐Through Head‐Mounted Displays

Author

Zhao, Chumin and Beams, Ryan

Abstract

We evaluate the geometric distortion on video see‐through (VST) head‐mounted displays (HMDs) with single‐camera and dualcamera design. We present the experimental setup and metrology for geometric calibration and VST geometric distortion measurement. Physical geometric distortion is compared to the distortion of digital content on a VST HMD. We investigate the impacts of camera misalignment and depth distance on VST geometric distortion with angular‐based distortion correction.

Published
2024
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14. Geometric distortion on video see‐through head‐mounted displays.

Author

Zhao, Chumin and Beams, Ryan

Subjects
*HEAD-mounted displays, *VIDEOS, *AUGMENTED reality
Abstract

Video see‐through (VST) head‐mounted displays (HMDs) reconstruct the physical world using outward‐facing cameras and depth sensors. One of the major challenges for VST HMDs is the geometric distortion of the physical pass‐through content. In this study, we present the experimental setup and metrology for VST geometric distortion measurement on single‐camera and dual‐camera VST HMDs. The VST geometric distortion is compared to the digital distortion by the HMD. Finally, we investigate the impacts of camera misalignment and depth distance on VST geometric distortion without and with angular‐based distortion correction. The results demonstrate that camera misalignment with respect to the eye position is the primary root cause for the distortion. Dual‐camera setup is necessary to minimize the VST geometric distortion by placing the cameras close to the eye positions. Although distortion correction can partially mitigate VST geometric distortion in a 2D plane, it remains a challenge for VST distortion correction at multiple depth distance in the 3D space. The method and findings presented of this study may provide guidelines for evaluation of spatial accuracy on VST HMDs and hardware design. [ABSTRACT FROM AUTHOR]

Published
2024
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28. 82‐1: Distinguished Paper:Radially Variant Contrast in Virtual Reality Headsets

Author

Zhao, Chumin, Beams, Ryan, and Badano, Aldo

Abstract

Monocular image quality on virtual reality (VR) head‐mounted displays (HMDs) is radially variant on each eye piece. The virtual image is blurred at the periphery of display field of view primarily by thin lenses stacked on top of the VR display backplane, resulting in image resolution and contrast degradation. Conventional measurement methods adopted from flat‐panel display evaluation do not consider the spatially variant image artifacts by the additional optical components, and thus may not be adequate to assess the image quality in VR. We develop novel test patterns and a new method to measure the radially variant Michelson contrast on VR HMDs. The new method demonstrates efficient VR image quality evaluation using varied interpupillary distance settings.

Published
2023
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40. Screening and verification of outer membrane proteins of Cronobacter sakazakiiwith potential adhesion capability to human ileocecal adenocarcinoma cells

Author

Zhao, Chumin, Li, Ping, Fan, Yufei, Zhu, Dongdong, Jiao, Jingbo, Li, Yue, Xiao, Zehui, Du, Xinjun, and Wang, Shuo

Abstract

Cronobacter sakazakii(C. sakazakii), a food-borne pathogen, can cause severe intestinal diseases, such as intestinal damage and necrotizing enterocolitis, and even death in neonates and infants through its adhesion to intestinal epithelium cells by protein-protein interaction and translocation across the intestinal barrier. Nevertheless, the mechanisms of adhesion, translocation, and pathogenesis remain unclear. This study aimed to screen and validate the outer membrane proteins of C. sakazakiicapable of adhering to the surface of intestinal cells through biotinylated protein adhesion and LC-MS/MS identification. A total of 319 proteins were identified. Gene Ontology and KEGG analysis revealed significant enrichment of ligand proteins in metabolism-related processes and catalytic activity. The identified 37 outer membrane proteins and 41 proteins of unknown subcellular localization or function mainly enriched in five protein-protein interaction clusters. Ten of these outer membrane/unknown proteins were selected to test their roles on C. sakazakiiadhesion and invasion of intestinal cells by silencing the encoding gene expression and nine of the ten proteins, Protein_26/30/34/38/42/98/104/194/282, were shown to be critical in this process. This study contributes to the understanding of proteins involved in the host adhesion process by C. sakazakiias well as the mechanisms for its translocation across the intestinal barrier.

Published
2024
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