Prof. Alexander Wong Profile

Prof. Alexander Wong

at Univ of Waterloo

SPIE Involvement:

Author

Publications (37)

Proceedings Article | 8 April 2024 Presentation

Transient blood flow changes in the human retina in response to flicker stimulation measured with a combined OCT+ERG system

Khushmeet Dhaliwal, James Simmons, Alex Wong, Chris Hudson, Nadine Furtado, Tom Wright, Brian Ballios, Kostadinka Bizheva

Proceedings Volume PC12824, PC128240L (2024) https://doi.org/10.1117/12.3001798

KEYWORDS: Blood circulation, Optical coherence tomography, Retina, Visualization, Retinal diseases, Human subjects, Glaucoma, Frequency response, Doppler effect, Data acquisition

Read Abstract +

Proceedings Article | 13 March 2024 Poster

Non-stationary diffraction and defocus correction in optical coherence tomography images

Nima Abbasi, Keyu Chen, Alexander Wong, Kostadinka Bizheva

Proceedings Volume PC12830, PC128301P (2024) https://doi.org/10.1117/12.3005756

KEYWORDS: Optical coherence tomography, Diffraction, Tissues, Optical limiting, Image quality, Detection and tracking algorithms, Biological samples, Statistical modeling, Optical resolution, Optical imaging

Read Abstract +

Proceedings Article | 13 March 2024 Presentation

Second generation Powell lens line-field OCT for in-vivo, contactless, volumetric imaging of the cellular structure of the human cornea

Keyu Chen, Nima Abbasi, Alexander Wong, Kostadinka Bizheva

Proceedings Volume PC12824, PC128240V (2024) https://doi.org/10.1117/12.3005735

KEYWORDS: Cornea, In vivo imaging, Corneal imaging, Optical coherence tomography, Imaging systems, Visualization, Tissues, Optical design, Image resolution, Eye

Read Abstract +

Proceedings Article | 13 March 2024 Presentation

Computational approach to correcting defocus in human corneal images acquired with Powell lens line-field OCT

Nima Abbasi Firoozjah, Keyu Chen, Alexander Wong, Kostadinka Bizheva

Proceedings Volume PC12824, PC128240X (2024) https://doi.org/10.1117/12.3005888

KEYWORDS: Optical coherence tomography, Depth of field, Optical limiting, Image quality, Algorithm development, Yield improvement, Tissues, Optical signal processing, Optical imaging, Optical design

Read Abstract +

Proceedings Article | 13 March 2024 Presentation

Visually-evoked retinal blood vessel dilation in the human optic nerve head evaluated with a combined OCT+ERG system

Khushmeet Dhaliwal, James Simmons, Yadushan Thurairasa, Alex Wong, Chris Hudson, Nadine Furtado, Tom Wright, Brian Ballios, Kostadinka Bizheva

Proceedings Volume PC12830, PC1283003 (2024) https://doi.org/10.1117/12.3001795

KEYWORDS: Blood vessels, Visualization, Optical coherence tomography, Retinal diseases, Optic nerve, Head, Vascular diseases, Neurological disorders, Glaucoma, Frequency response

Read Abstract +

SPIE Journal Paper | 8 September 2020 Open Access

Global chlorophyll-a concentration estimation from moderate resolution imaging spectroradiometer using convolutional neural networks

Bowen Yu, Linlin Xu, Jun-huan Peng, Zhongzheng Hu, Alexander Wong

JARS, Vol. 14, Issue 03, 034520, (September 2020) https://doi.org/10.1117/12.10.1117/1.JRS.14.034520

KEYWORDS: MODIS, Data modeling, Image resolution, Satellites, Remote sensing, Convolution, Convolutional neural networks, Neurons, Machine learning, Statistical modeling

Read Abstract +

The accurate estimation of global chlorophyll-a (Chla) concentration from the large remote sensing data in a timely manner is crucial for supporting various applications. Moderate resolution imaging spectroradiometer (MODIS) is one of the most widely used earth observation data sources, which has the characteristics of global coverage, high spectral resolution, and short revisit period. So the estimation of global Chla concentration from MODIS imagery in a fast and accurate manner is significant. Nevertheless, the estimation of Chla concentration from MODIS using traditional machine learning approaches is challenging due to their limited modeling capability to capture the complex relationship between MODIS spatial–spectral observations and the Chla concentration, and also their low computational efficiency to address large MODIS data in a timely manner. We, therefore, explore the potential of deep convolutional neural networks (CNNs) for Chla concentration estimation from MODIS imagery. The Ocean Color Climate Change Initiative (OC-CCI) Chla concentration image is used as ground truth because it is a well-recognized Chla concentration product that is produced by assimilating different satellite data through a complex data processing steps. A total of 12 monthly OC-CCI global Chla concentration maps and the associated MODIS images are used to investigate the CNN approach using a cross-validation approach. The classical machine learning approach, i.e., the supported vector regression (SVR), is used to compare with the proposed CNN approach. Comparing with the SVR, the CNN performs better with the mean log root-mean-square error and R2 of being 0.129 and 0.901, respectively, indicating that using the MODIS images alone, the CNN approach can achieve results that is close to the OC-CCI Chla concentration images. These results demonstrate that CNNs may provide Chla concentration images that are reliable, stable and timely, and as such CNN constitutes a useful technique for operational Chla concentration estimation from large MODIS data.

DOWNLOAD PAPER

Proceedings Article | 4 March 2019 Paper

Resolution-enhanced digital epiluminescence microscopy using deep computational optics

Dino Kabiljagic, Alexander Wong

Proceedings Volume 10881, 108811P (2019) https://doi.org/10.1117/12.2507484

KEYWORDS: Skin, Digital imaging, Optical signal processing, Computational imaging, Spatial resolution, Skin cancer, Image enhancement, Cancer, Calibration, Microscopy

Read Abstract +

Proceedings Article | 4 March 2019 Paper

A multispectral Bayesian-based computational microscopy method for enhancing image quality

Jason Deglint, Chao Jin, Alexander Wong

Proceedings Volume 10881, 1088117 (2019) https://doi.org/10.1117/12.2506894

KEYWORDS: Image enhancement, Microscopy, Point spread functions, Image quality, Water, Chromatic aberrations, Image processing, Imaging systems

Read Abstract +

Proceedings Article | 28 February 2019 Paper

Fully automated corneal nerve segmentation algorithm for corneal nerves analysis from in-vivo UHR-OCT images

Zohreh Hosseinaee, Bingyao Tan, Olivera Kralj, Le Han, Alexander Wong, Luigina Sorbara, Kostadinka Bizheva

Proceedings Volume 10858, 1085823 (2019) https://doi.org/10.1117/12.2513288

KEYWORDS: Image segmentation, Nerve, In vivo imaging, Optical coherence tomography, Eye, Imaging systems, Cornea, Image processing algorithms and systems, Diffusion, Image resolution

Read Abstract +

Proceedings Article | 21 February 2019 Paper

Enhanced spectral lightfield fusion microscopy via deep computational optics for whole-slide pathology

Farnoud Kazemzadeh, Hector Li-Chang, Alexander Wong

Proceedings Volume 10883, 1088312 (2019) https://doi.org/10.1117/12.2510952

KEYWORDS: Microscopy, Computer programming, Pathology, Interferometry, Computational imaging, Digital signal processing

Read Abstract +

Proceedings Article | 20 February 2018 Paper

Non-contact assessment of obstructive sleep apnea cardiovascular biomarkers using photoplethysmography imaging

Robert Amelard, Kaylen Pfisterer, Shubh Jagani, David Clausi, Alexander Wong

Proceedings Volume 10501, 1050113 (2018) https://doi.org/10.1117/12.2290672

KEYWORDS: Photoplethysmography, Absorbance, Imaging systems, Arteries, Hemodynamics, Blood, Blood circulation, Sensors

Read Abstract +

Proceedings Article | 20 February 2018 Paper

Computational circular dichroism estimation for point-of-care diagnostics via vortex half-wave retarders

Shahid Haider, Megan Tran, Alexander Wong

Proceedings Volume 10501, 1050108 (2018) https://doi.org/10.1117/12.2290619

KEYWORDS: Wave plates, Polarization, Detector arrays, Point-of-care devices, Diagnostics, Dichroic materials, Molecules, Optical activity, Biological research

Read Abstract +

Proceedings Article | 20 February 2018 Paper

Differential color space analysis for investigating nutrient content in a pureed food dilution-flavor matrix: a step toward objective malnutrition risk assessment

Kaylen Pfisterer, Robert Amelard, Alexander Wong

Proceedings Volume 10501, 105010J (2018) https://doi.org/10.1117/12.2289028

KEYWORDS: Food inspection, Absorption, RGB color model, Reflectivity, Chromophores, Absorbance, Imaging systems

Read Abstract +

SPIE Journal Paper | 17 October 2017

Fully automated segmentation of prostate whole gland and transition zone in diffusion-weighted MRI using convolutional neural networks

Tyler Clark, Junjie Zhang, Sameer Baig, Alexander Wong, Masoom Haider, Farzad Khalvati

JMI, Vol. 4, Issue 04, 041307, (October 2017) https://doi.org/10.1117/12.10.1117/1.JMI.4.4.041307

KEYWORDS: Image segmentation, Prostate, Magnetic resonance imaging, Diffusion weighted imaging, Convolution, Convolutional neural networks, Prostate cancer, Image processing algorithms and systems, 3D image processing, Detection and tracking algorithms

Read Abstract +

Proceedings Article | 21 March 2017 Paper

Computational laser intensity stabilisation for organic molecule concentration estimation in low-resource settings

Shahid Haider, Farnoud Kazemzadeh, Alexander Wong

Proceedings Volume 10055, 100550W (2017) https://doi.org/10.1117/12.2253380

KEYWORDS: Computational modeling, Gas lasers, Biological research, Laser stabilization, Polarization, Helium neon lasers, Biomedical optics, Doppler effect, Linear polarizers

Read Abstract +

Proceedings Article | 17 February 2017 Presentation + Paper

Assessing photoplethysmographic imaging performance beyond facial perfusion analysis

Robert Amelard, Richard Hughson, Danielle Greaves, David Clausi, Alexander Wong

Proceedings Volume 10072, 100720Q (2017) https://doi.org/10.1117/12.2252114

KEYWORDS: Photoplethysmography, Imaging systems, Arteries, Diffuse reflectance spectroscopy, Bandpass filters, Sensing systems, Tissue optics, Blood, Biomedical optics, Heart, Hemodynamics, Ultrasonography, Neck, Analytical research

Read Abstract +

Proceedings Article | 17 February 2017 Presentation + Paper

A stochastically fully connected conditional random field framework for super resolution OCT

A. Boroomand, B. Tan, A. Wong, K. Bizheva

Proceedings Volume 10053, 100532C (2017) https://doi.org/10.1117/12.2250645

KEYWORDS: Optical coherence tomography, Super resolution, Image resolution, Speckle, Image quality, Lawrencium, Point spread functions, Spatial resolution, Retina, Visualization

Read Abstract +

Proceedings Article | 8 February 2017 Presentation + Paper

Non-contact arrhythmia assessment in natural settings: a step toward preventive cardiac care

Robert Amelard, Richard Hughson, David Clausi, Alexander Wong

Proceedings Volume 10042, 1004205 (2017) https://doi.org/10.1117/12.2252133

KEYWORDS: Photoplethysmography, Blood, Imaging systems, Cardiovascular system, Hemodynamics, Signal detection, Diagnostics and therapeutics, Cardiology, Time-frequency analysis, Wavelets, Heart, Absorbance, Image fusion, Near infrared

Read Abstract +

SPIE Journal Paper | 25 November 2016 Open Access

Spatial probabilistic pulsatility model for enhancing photoplethysmographic imaging systems

Robert Amelard, David Clausi, Alexander Wong

JBO, Vol. 21, Issue 11, 116010, (November 2016) https://doi.org/10.1117/12.10.1117/1.JBO.21.11.116010

KEYWORDS: Photoplethysmography, Systems modeling, Blood, Data modeling, Statistical modeling, Heart, Imaging systems, Signal to noise ratio, Beam propagation method, Error analysis

Read Abstract +

DOWNLOAD PAPER

Proceedings Article | 10 March 2016 Paper

Photoplethysmographic imaging via spectrally demultiplexed erythema fluctuation analysis for remote heart rate monitoring

Jason Deglint, Audrey Chung, Brendan Chwyl, Robert Amelard, Farnoud Kazemzadeh, Xiao Yu Wang, David Clausi, Alexander Wong

Proceedings Volume 9701, 970111 (2016) https://doi.org/10.1117/12.2213532

KEYWORDS: Photoplethysmography, Heart, RGB color model, Imaging systems, Skin, Reflectivity, Motion analysis, Digital cameras, Video, Cameras, Sensors, Beam propagation method

Read Abstract +

Proceedings Article | 10 March 2016 Paper

Non-contact hematoma damage and healing assessment using reflectance photoplethysmographic imaging

Robert Amelard, Kaylen Pfisterer, David Clausi, Alexander Wong

Proceedings Volume 9701, 970112 (2016) https://doi.org/10.1117/12.2213539

KEYWORDS: Optical components, Photoplethysmography, Tissues, Reflectivity, Visualization, Near infrared, Blood, Blood circulation, Wound healing, Data acquisition, Absorption, Imaging systems, Absorbance, Heart, Hemodynamics

Read Abstract +

Proceedings Article | 10 March 2016 Paper

Spectral photoplethysmographic imaging sensor fusion for enhanced heart rate detection

Robert Amelard, David Clausi, Alexander Wong

Proceedings Volume 9701, 970113 (2016) https://doi.org/10.1117/12.2213687

KEYWORDS: Photoplethysmography, Heart, Sensors, Skin, Hemodynamics, Blood, Signal to noise ratio, Sensor fusion, Imaging systems, Fusion energy, Near infrared

Read Abstract +

Proceedings Article | 22 September 2015 Paper

Virtual spectral multiplexing for applications in in-situ imaging microscopy of transient phenomena

Jason Deglint, Farnoud Kazemzadeh, Mohammad Javad Shafiee, Edward Li, Iman Khodadad, Simarjeet Saini, Alexander Wong, David Clausi

Proceedings Volume 9599, 95992D (2015) https://doi.org/10.1117/12.2188228

KEYWORDS: Microscopy, Imaging systems, Sensors, Multiplexing, RGB color model, Data modeling, Signal detection, Microscopes, Spectroscopy, Nanowires

Read Abstract +

Proceedings Article | 22 September 2015 Paper

Inference of dense spectral reflectance images from sparse reflectance measurement using non-linear regression modeling

Jason Deglint, Farnoud Kazemzadeh, Alexander Wong, David Clausi

Proceedings Volume 9599, 95992G (2015) https://doi.org/10.1117/12.2188262

KEYWORDS: RGB color model, Data modeling, Cameras, Reflectivity, Multispectral imaging, Imaging devices, Imaging systems, Light sources, Hyperspectral imaging, Nonlinear optics

Read Abstract +

Proceedings Article | 4 September 2015 Paper

Sparse reconstruction of compressed sensing multispectral data using a cross-spectral multilayered conditional random field model

Edward Li, Mohammad Javad Shafiee, Farnoud Kazemzadeh, Alexander Wong

Proceedings Volume 9599, 959902 (2015) https://doi.org/10.1117/12.2188252

KEYWORDS: Compressed sensing, Data modeling, Reconstruction algorithms, Imaging systems, Sensors, Cameras, Image resolution, Multilayers, Visualization, Spatial resolution

Read Abstract +

Proceedings Article | 3 September 2015 Paper

Concurrent fluorescence macro-imaging across multiple spectral regions in the visible and the near infrared

Farnoud Kazemzadeh, Shahid Haider, Chao Jin, David Clausi, Alexander Wong

Proceedings Volume 9579, 957907 (2015) https://doi.org/10.1117/12.2188209

KEYWORDS: Imaging systems, Luminescence, Cameras, Sensors, Visible radiation, Near infrared, Optical filters, Multispectral imaging, Light sources, Image resolution

Read Abstract +

Proceedings Article | 3 September 2015 Paper

Multispectral digital holographic microscopy with applications in water quality assessment

Farnoud Kazemzadeh, Chao Jin, Mei Yu, Robert Amelard, Shahid Haider, Simarjeet Saini, Monica Emelko, David Clausi, Alexander Wong

Proceedings Volume 9579, 957906 (2015) https://doi.org/10.1117/12.2187705

KEYWORDS: Digital holography, Holography, Water, Microscopy, Microscopes, Imaging systems, Image resolution, Interferometry, Contamination, Sensors

Read Abstract +

Proceedings Article | 1 September 2015 Paper

Integrated computational imaging system for enhanced polarimetric measurements

Shahid Haider, Farnoud Kazemzadeh, David Clausi, Alexander Wong

Proceedings Volume 9613, 961309 (2015) https://doi.org/10.1117/12.2188276

KEYWORDS: Polarimetry, Sensors, Computing systems, Detector arrays, Computational imaging, Molecules, Polarization, Imaging systems, Polarizers, System integration

Read Abstract +

Proceedings Article | 5 March 2015 Paper

Non-contact assessment of melanin distribution via multispectral temporal illumination coding

Robert Amelard, Christian Scharfenberger, Alexander Wong, David Clausi

Proceedings Volume 9316, 93160N (2015) https://doi.org/10.1117/12.2078393

KEYWORDS: Light emitting diodes, Cameras, Skin, Chromophores, Ultraviolet radiation, Melanoma, Visible radiation, Electromagnetism, Imaging systems, Near infrared

Read Abstract +

Proceedings Article | 5 March 2015 Paper

Illumination-compensated non-contact imaging photoplethysmography via dual-mode temporally coded illumination

Robert Amelard, Christian Scharfenberger, Alexander Wong, David Clausi

Proceedings Volume 9316, 931607 (2015) https://doi.org/10.1117/12.2078197

KEYWORDS: Cameras, Heart, Blood, Imaging systems, Light emitting diodes, Microcontrollers, Light sources and illumination, Light, Absorbance, Photoplethysmography

Read Abstract +

Proceedings Article | 5 March 2015 Paper

High-resolution motion-compensated imaging photoplethysmography for remote heart rate monitoring

Audrey Chung, Xiao Yu Wang, Robert Amelard, Christian Scharfenberger, Joanne Leong, Jan Kulinski, Alexander Wong, David Clausi

Proceedings Volume 9316, 93160A (2015) https://doi.org/10.1117/12.2078397

KEYWORDS: Heart, Video, Skin, Imaging systems, Motion measurement, Beam propagation method, Independent component analysis, Blood, Biological research, Photoplethysmography

Read Abstract +

Proceedings Article | 4 March 2015 Paper

Restoration of block-transform compressed images via homotopic regularized sparse reconstruction

Jeffrey Glaister, Shahid Haider, Alexander Wong, David Clausi

Proceedings Volume 9410, 941005 (2015) https://doi.org/10.1117/12.2082861

KEYWORDS: Image compression, Reconstruction algorithms, Quantization, Image processing, Image quality, Visualization, Video compression, Video, Image restoration, Image quality standards

Read Abstract +

Proceedings Article | 2 March 2015 Paper

Lateral resolution enhancement via imbricated spectral domain optical coherence tomography in a maximum-a-posterior reconstruction framework

A. Boroomand, M. Shafiee, A. Wong, K. Bizheva

Proceedings Volume 9312, 931240 (2015) https://doi.org/10.1117/12.2081494

KEYWORDS: Optical coherence tomography, Image resolution, Resolution enhancement technologies, Image enhancement, Spectral resolution, Imaging systems, Deconvolution, Image analysis, Image processing, Cornea

Read Abstract +

Proceedings Article | 2 March 2015 Paper

Axial resolution improvement in spectral domain optical coherence tomography using a depth-adaptive maximum-a-posterior framework

Ameneh Boroomand, Bingyao Tan, Alexander Wong, Kostadinka Bizheva

Proceedings Volume 9312, 931241 (2015) https://doi.org/10.1117/12.2081493

KEYWORDS: Optical coherence tomography, Image resolution, Point spread functions, Imaging systems, Deconvolution, Spectral resolution, Resolution enhancement technologies, Visualization, Speckle, Stochastic processes

Read Abstract +

Proceedings Article | 8 February 2015 Paper

Multi-polarimetric textural distinctiveness for outdoor robotic saliency detection

S. A. Haider, C. Scharfenberger, F. Kazemzadeh, A. Wong, D. Clausi

Proceedings Volume 9406, 94060A (2015) https://doi.org/10.1117/12.2082860

KEYWORDS: Polarization, Polarimetry, Robotics, Cameras, Chemical species, Volume rendering, Mobile robots, Color imaging, Visible radiation, Statistical modeling

Read Abstract +

Proceedings Article | 23 September 2014 Paper

Reconstruction of compressive multispectral sensing data using a multilayered conditional random field approach

Farnoud Kazemzadeh, Mohammad Shafiee, Alexander Wong, David Clausi

Proceedings Volume 9217, 921712 (2014) https://doi.org/10.1117/12.2062135

KEYWORDS: Reconstruction algorithms, Data acquisition, Sensors, Image compression, Compressed sensing, Multilayers, Chromium, Imaging systems, Bandpass filters, Image restoration

Read Abstract +

Proceedings Article | 12 February 2011 Paper

Despeckling vs averaging of retinal UHROCT tomograms: advantages and limitations

Justin Eichel, Donghyun Lee, Alexander Wong, Paul Fieguth, David Clausi, Kostadinka Bizheva

Proceedings Volume 7889, 78893C (2011) https://doi.org/10.1117/12.875867

KEYWORDS: Composites, Signal to noise ratio, Optical coherence tomography, Image quality, Speckle, Image processing, Image registration, Denoising, Imaging systems, Retina

Read Abstract +

Showing 5 of 37 publications

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years