Prof. Homer H. Chen Profile

Prof. Homer H. Chen

at National Taiwan Univ.

SPIE Involvement:

Author

Publications (17)

Proceedings Article | 12 March 2024 Presentation + Paper

Using autofocus data for 3D hand interaction

Chan-Yuan Huang, Chen-Han Lin, Homer Chen

Proceedings Volume 12913, 129130L (2024) https://doi.org/10.1117/12.3000801

KEYWORDS: Cameras, Distance measurement, Detection and tracking algorithms, 3D tracking, Gesture recognition, Calibration, Virtual reality

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Proceedings Article | 12 March 2024 Presentation + Paper

Geometric waveguide optimization for ghost reduction in near-eye light field display

Shan-Ling Chen, Li-Wei Fu, Jiun-Woei Huang, Kuang-Tsu Shih, Homer Chen

Proceedings Volume 12913, 129130H (2024) https://doi.org/10.1117/12.3003216

KEYWORDS: Waveguides, Reflection, Near eye displays, Mirrors, Eye, Stray light, Image quality, Visualization, Spatial resolution, Eye models

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Most near-eye displays with one fixed focal plane suffer from the vergence-accommodation conflict (VAC) and cause visual discomfort to users. In contrast, a light field display with continuous focal planes offers the most natural and comfortable AR/VR visual experiences without VAC and holds the promise to be the ultimate near-eye 3-D display. It projects light rays onto human retina as if the light rays were emanated from a real object. This paper considers a near-eye light field display comprising a light field generator, a collimator, and a geometric waveguide as the three main components. It takes 4-D light field data in the form of an array of 2-D subview images as input and generates a light field as output. The light field generator is the device responsible for converting the light emitted from the display panel to the light representing the light field of a virtual scene. The geometric waveguide along with a collimator ensures that the light rays propagating in the waveguide are collimated. The partially reflective mirrors of the waveguide replicate the optical path to achieve exit pupil expansion (EPE) and a large eyebox. However, existing waveguide eyepieces for near-eye AR/VR displays are not designed for, and hence may not fit light field displays. In this work, we look into a geometric waveguide for light field display and find that the light fields replicated by the partially reflective mirrors cannot perfectly overlap on the user’s retina, resulting in the appearance of multiple repetitive images—a phenomenon we call “ghost artifact”. This paper delves into the cause of this artifact and develops a solution for applications that require short-range interaction with virtual objects, such as surgical procedures. We define a working range devoid of noticeable ghost artifact based on the angular resolution characteristics of human eye and optimize the orientation of an array of partially reflective mirrors of the waveguide to meet the image quality requirement for short-range interaction. With the optimized waveguide, the ghost artifact is significantly reduced. More results of the optimized waveguide will be shown at the conference.

Proceedings Article | 16 March 2023 Presentation + Paper

A novel birdbath eyepiece for light field AR glasses

Chao-Chien Wu, Kuang-Tsu Shih, Jiun-Woei Huang, Homer H. Chen

Proceedings Volume 12449, 124490N (2023) https://doi.org/10.1117/12.2647315

KEYWORDS: Augmented reality, Glasses, Near eye displays, Design and modelling, Eye

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Natural and comfortable visual experience is critical to the success of metaverse, which has recently drawn worldwide attention. However, due to the vergence-accommodation conflict (VAC), most augmented reality (AR) or virtual reality (VR) displays on the market today can easily cause visual discomfort or eyestrain to users. Being able to resolve the VAC, light field display is commonly believed to be the ultimate display for metaverse. Similar to conventional near-eye AR displays, a near-eye light field AR display consists of three basic components: light source, projection unit, and eyepiece. Although the same light source can be used in both kinds of displays, the projection unit and the eyepiece of a near-eye light field AR display call for a new design to preserve the structure of light field when it reaches user’s retina. The primary focus of this paper is on the eyepiece design for a near-eye light field AR display. In consideration of the compact form factor and wide field of view, the birdbath architecture, which consists of a beam splitter and a combiner, is selected as the basis of our eyepiece design. We optimize the birdbath eyepiece for the light field projection module produced by PetaRay Inc. The birdbath eyepiece receives the light field emitted from the light field projection module and projects it fully into the user’s eye. Our design preserves the structure of light field and hence allows virtual objects at different depths to be properly perceived. In addition, the eyepiece design leads to a compact form factor for the near-eye light field AR display. Specifically, our eyepiece is designed by optimizing the tradeoff between the eyebox and the depth of focus (DOF) of the near-eye light field AR display. The resulting DOF allows the user to have a clear and sharp perception of any virtual object in the working range, which is from 30 cm to infinity. In addition, we optimize the entrance pupil position and the F-number of the eyepiece according to the exit pupil position and the divergence angle of the light field projection module. This way, the eyepiece is able to preserve the structure of light field, meaning that the angular relation between light rays coming from the same object point in space is preserved. To demonstrate the performance of our birdbath eyepiece, we use the Human Eye Model-Liou & Brennan (JOSA A 08/97) to simulate the image formation process.

SPIE Journal Paper | 3 May 2019

Modeling phase shift data of phase-detection autofocus by skew-normal distribution

Chin-Cheng Chan, Homer Chen

JEI, Vol. 28, Issue 03, 033001, (May 2019) https://doi.org/10.1117/12.10.1117/1.JEI.28.3.033001

KEYWORDS: Phase shifts, Data modeling, Sensors, Image sensors, Statistical analysis, Cameras, Image processing, Gaussian filters, Point spread functions, Reliability

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Proceedings Article | 27 February 2015 Paper

Overcoming the blooming effect on autofocus by fringe detection

Shao-Kang Huang, Dong-Chen Tsai, Homer Chen

Proceedings Volume 9404, 94040M (2015) https://doi.org/10.1117/12.2074816

KEYWORDS: Sensors, Image filtering, Cameras, Digital cameras, Photons, Image sensors, Image processing, Imaging systems, Image enhancement, Digital photography

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SPIE Journal Paper | 31 January 2013

Compensating specular highlights for non-Lambertian projection surfaces

Chen-Tai Kao, Tai-Hsiang Huang, Hua Lee, Homer Chen

JEI, Vol. 22, Issue 01, 011004, (January 2013) https://doi.org/10.1117/12.10.1117/1.JEI.22.1.011004

KEYWORDS: Cameras, Calibration, Projection systems, Image quality, Distortion, 3D modeling, Visualization, Reflectivity, Image analysis, Fourier transforms

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Proceedings Article | 21 February 2012 Paper

Quality assessment of images illuminated by dim LCD backlight

Tai-Hsiang Huang, Chen-Tai Kao, Homer Chen

Proceedings Volume 8291, 82911Q (2012) https://doi.org/10.1117/12.919904

KEYWORDS: Image quality, LCDs, Eye, Distortion, Image processing, Lanthanum, Electronic imaging, Reflective displays, Databases, Quality measurement

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Proceedings Article | 24 September 2011 Paper

Color enhancement for portable LCD displays in low-power mode

Kuang-Tsu Shih, Tai-Hsiang Huang, Homer Chen

Proceedings Volume 8135, 81350V (2011) https://doi.org/10.1117/12.895550

KEYWORDS: Image enhancement, LCDs, Human vision and color perception, Instrument modeling, Image quality, Colorimetry, Image processing, Superposition, Detection and tracking algorithms, Imaging devices

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Proceedings Article | 10 February 2009 Paper

Efficient construction of saliency map

Wen-Fu Lee, Tai-Hsiang Huang, Yi-Hsin Huang, Mei-Lan Chu, Homer Chen

Proceedings Volume 7240, 724018 (2009) https://doi.org/10.1117/12.811166

KEYWORDS: Visualization, Visual process modeling, Spatial frequencies, Image processing, Detection and tracking algorithms, Visual system, Signal processing, Image fusion, Information visualization, Image compression

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Proceedings Article | 29 January 2007 Paper

Edge-based automatic white balancing with linear illuminant constraint

Homer Chen, Chun-Hung Shen, Pei-Shan Tsai

Proceedings Volume 6508, 65081D (2007) https://doi.org/10.1117/12.704020

KEYWORDS: Sensors, Edge detection, Cameras, Light sources, Reflectivity, Error analysis, Detection and tracking algorithms, RGB color model, Black bodies, Digital cameras

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Proceedings Article | 24 June 2005 Paper

Rolling shutter distortion correction

Chia-Kai Liang, Yu-Chun Peng, Homer Chen

Proceedings Volume 5960, 59603V (2005) https://doi.org/10.1117/12.632671

KEYWORDS: Camera shutters, Cameras, Distortion, CMOS sensors, Motion estimation, Video, Mathematical modeling, Image sensors, Digital image processing, Analog electronics

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Proceedings Article | 28 December 1998 Paper

Robust image compression with packetization: the JPEG-2000 case

Iole Moccagatta, Osama Al-Shaykh, Homer Chen

Proceedings Volume 3653, (1998) https://doi.org/10.1117/12.334715

KEYWORDS: Computer programming, Image compression, Wavelets, Image quality, Standards development, Multimedia, Image processing, Quantization, Image quality standards, Internet

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Proceedings Article | 17 July 1998 Paper

Contrast gain control for color image quality

Michael D'Zmura, Tsae-Pyng Shen, Wei Wu, Homer Chen, Marius Vassiliou

Proceedings Volume 3299, (1998) https://doi.org/10.1117/12.320111

KEYWORDS: Visual process modeling, Spatial frequencies, Image quality, Image compression, Visualization, Image processing, Colorimetry, Visual compression, Visual system, Contrast sensitivity

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Proceedings Article | 21 April 1995 Paper

Lip synchronization in talking head video utilizing speech information

Tsuhan Chen, H. Graf, Homer Chen, Wu Chou, Barry Haskell, Eric Petajan, Yao Wang

Proceedings Volume 2501, (1995) https://doi.org/10.1117/12.206706

KEYWORDS: Mouth, Laser induced plasma spectroscopy, Video, Image analysis, Head, Eye, Video coding, Detection and tracking algorithms, Image processing, Image quality standards

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Proceedings Article | 21 April 1995 Paper

Speech recognition for acoustic-assisted video coding and animation

Homer Chen, Wu Chou, Barry Haskell, Tsuhan Chen

Proceedings Volume 2501, (1995) https://doi.org/10.1117/12.206731

KEYWORDS: Acoustics, Mouth, Visualization, 3D modeling, Video, Laser induced plasma spectroscopy, Speech recognition, Video coding, Image compression, Computer programming

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Proceedings Article | 21 April 1995 Paper

Joint motion estimation and segmentation for very low bit rate video coding

Touradj Ebrahimi, Homer Chen, Barry Haskell

Proceedings Volume 2501, (1995) https://doi.org/10.1117/12.206785

KEYWORDS: Motion estimation, Video coding, Image segmentation, Image quality, Motion measurement, Video, Visualization, Low bit rate video, Computer programming, Motion detection

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Proceedings Article | 21 April 1995 Paper

Mouth shape detection and tracking using an active mesh

Yao Wang, Ru-Shang Wang, Ouseb Lee, Tsuhan Chen, Homer Chen, Barry Haskell

Proceedings Volume 2501, (1995) https://doi.org/10.1117/12.206647

KEYWORDS: Mouth, Detection and tracking algorithms, Laser induced plasma spectroscopy, Chemical elements, Finite element methods, Computer simulations, Algorithm development, Teeth, Eye models, Head

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Showing 5 of 17 publications

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