Dr. Brian W. Keelan Profile

Dr. Brian W. Keelan

Senior Research Staff

SPIE Involvement:

Author | Instructor

Publications (16)

Proceedings Article | 24 January 2012 Paper

Sensor defect probability estimation and yield

Honghong Peng, Brian Keelan

Proceedings Volume 8299, 829903 (2012) https://doi.org/10.1117/12.912142

KEYWORDS: Sensors, Numerical simulations, Image quality, Defect detection, Detection and tracking algorithms, Image sensors, Visualization, Retina, Digital photography, Electronic imaging

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Proceedings Article | 24 January 2012 Paper

Detection thresholds of structured noise in the presence of shot noise

Feng Li, Brian Keelan, Robin Jenkin, Alex Dokoutchaev

Proceedings Volume 8299, 82990B (2012) https://doi.org/10.1117/12.909588

KEYWORDS: Signal to noise ratio, Visualization, Interference (communication), Sensors, Modulation transfer functions, Electrons, Visual system, Data modeling, Detection theory, Contrast sensitivity

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Proceedings Article | 24 January 2012 Paper

Quality versus color saturation and noise

Brian Keelan, Robin Jenkin, Elaine Jin

Proceedings Volume 8299, 82990F (2012) https://doi.org/10.1117/12.905377

KEYWORDS: Signal to noise ratio, Image quality, Interference (communication), RGB color model, Cameras, Steiner quadruple pulse system, Visualization, Solids, Signal attenuation, Sensors

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Proceedings Article | 24 January 2011 Paper

Perceptually relevant evaluation of noise power spectra in adaptive pictorial systems

Robin Jenkin, Brian Keelan

Proceedings Volume 7867, 786708 (2011) https://doi.org/10.1117/12.871848

KEYWORDS: Signal to noise ratio, Digital filtering, Denoising, RGB color model, Gaussian filters, Image filtering, Modulation transfer functions, Interference (communication), Imaging systems, Image processing

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Proceedings Article | 24 January 2011 Paper

Development of a perceptually calibrated objective metric of noise

Brian Keelan, Elaine Jin, Sergey Prokushkin

Proceedings Volume 7867, 786707 (2011) https://doi.org/10.1117/12.871633

KEYWORDS: Image quality, Steiner quadruple pulse system, Calibration, Cameras, Visualization, Modulation transfer functions, RGB color model, Interference (communication), Objectives, Retina

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Proceedings Article | 8 September 2010 Paper

Objective and subjective measurement and modeling of image quality: a case study

Brian Keelan

Proceedings Volume 7798, 779815 (2010) https://doi.org/10.1117/12.862523

KEYWORDS: Image quality, Modulation transfer functions, Signal to noise ratio, Quality measurement, Spatial frequencies, Systems modeling, Quantum efficiency, Visualization, Interference (communication), Image processing

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SPIE Journal Paper | 1 January 2010

Slider-adjusted softcopy ruler for calibrated image quality assessment

Elaine Jin, Brian Keelan

JEI, Vol. 19, Issue 01, 011009, (January 2010) https://doi.org/10.1117/12.10.1117/1.3271133

KEYWORDS: Image quality, Calibration, Sensors, Modulation transfer functions, Cameras, Distortion, Standards development, Image quality standards, Steiner quadruple pulse system, Image sensors

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Proceedings Article | 2 September 2009 Paper

Focus recovery for extended depth-of-field mobile imaging systems

Dan Lelescu, Kartik Venkataraman, Rob Mullis, Pravin Rao, Cheng Lu, Junqing Chen, Brian Keelan

Proceedings Volume 7443, 74430H (2009) https://doi.org/10.1117/12.824623

KEYWORDS: Image restoration, Point spread functions, Signal to noise ratio, Sensors, Interference (communication), Image processing, Imaging systems, Image sensors, Cameras, Signal processing

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Proceedings Article | 19 January 2009 Paper

Softcopy quality ruler method: implementation and validation

Elaine Jin, Brian Keelan, Junqing Chen, Jonathan Phillips, Ying Chen

Proceedings Volume 7242, 724206 (2009) https://doi.org/10.1117/12.805922

KEYWORDS: Modulation transfer functions, Image quality, Cameras, Standards development, Image quality standards, Steiner quadruple pulse system, Image processing, Zoom lenses, Digital imaging, Calibration

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Proceedings Article | 19 January 2009 Paper

Weighting of field heights for sharpness and noisiness

Brian Keelan, Elaine Jin

Proceedings Volume 7242, 72420Z (2009) https://doi.org/10.1117/12.805628

KEYWORDS: Image quality, Visualization, Modulation transfer functions, Photography, Interference (communication), Signal to noise ratio, Image segmentation, Manufacturing, Image processing, Data centers

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Proceedings Article | 11 September 2008 Paper

Imaging with depth extension: where are the limits in fixed-focus cameras?

Dmitry Bakin, Brian Keelan

Proceedings Volume 7061, 706106 (2008) https://doi.org/10.1117/12.795664

KEYWORDS: Cameras, Sensors, Image resolution, Point spread functions, Imaging systems, Solids, Image quality, Digital signal processing, Image processing, Modulation transfer functions

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Proceedings Article | 20 March 2007 Paper

Advanced system model for the prediction of the clinical task performance of radiographic systems

Karin Töpfer, Brian Keelan, Francisca Sugiro

Proceedings Volume 6515, 651512 (2007) https://doi.org/10.1117/12.709570

KEYWORDS: Sensors, Lung, Systems modeling, Dual energy imaging, Modulation transfer functions, Image processing, Visual process modeling, Radiography, Interference (communication), Target detection

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A flexible software tool was developed that combines predictive models for detector noise and blur with image simulation and an improved human observer model to predict the clinical task performance of existing and future radiographic systems. The model starts with high-fidelity images from a database and mathematical models of common disease features, which may be added to the images at desired contrast levels. These images are processed through the entire imaging chain including capture, the detector, image processing, and hardcopy or softcopy display. The simulated images and the viewing conditions are passed to a human observer model, which calculates the detectability index d' of the signal (disease or target feature). The visual model incorporates a channelized Hotelling observer with a luminance-dependent contrast sensitivity function and two types of internal visual system noise (intrinsic and image background-induced). It was optimized based on three independent human observer studies of target detection, and is able to predict d' over a wide range of viewing conditions, background complexities, and target spatial frequency content. A more intuitive metric of system performance, Task-Specific Detective Efficiency (TSDE), is defined to indicate how much detector improvements would translate to better radiologist performance. The TSDE is calculated as the squared ratio of d' for a system with the actual detector and a hypothetical system containing an ideal detector. A low TSDE, e.g., 5% for the detection of 0.1 mm microcalcifications in typical mammography systems, indicates that improvements in the detector characteristics are likely to translate to better detection performance. The TSDE of lung nodule detection is as high as 75% even with the detective quantum efficiency (DQE) of the detector not exceeding 24%. Applications of the model to system optimizations for flat-panel detectors, in mammography and dual energy digital radiography, are discussed.

Proceedings Article | 12 April 2005 Paper

Effect of grayscale resolution on the performance of lung nodule detection on a softcopy display

W. James Sehnert, Brian Keelan, Karin Toepfer

Proceedings Volume 5744, (2005) https://doi.org/10.1117/12.593766

KEYWORDS: Heart, Lung, LCDs, Calibration, Video, Sensors, Image resolution, Chest, X-rays, Selenium

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Proceedings Article | 17 January 2005 Paper

ISO 12232 revision: determination of chrominance noise weights for noise-based ISO calculation

Sean Kelly, Brian Keelan

Proceedings Volume 5668, (2005) https://doi.org/10.1117/12.582447

KEYWORDS: Visualization, Signal to noise ratio, Standards development, Cameras, Data modeling, Digital cameras, Device simulation, Image processing, Interference (communication), Image quality

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Proceedings Article | 4 May 2004 Paper

Relative impact of detector noise and anatomical structure on lung nodule detection

Brian Keelan, Karin Topfer, John Yorkston, William Sehnert, Jacquelyn Ellinwood

Proceedings Volume 5372, (2004) https://doi.org/10.1117/12.536733

KEYWORDS: Lung, Sensors, Heart, Signal to noise ratio, X-rays, X-ray imaging, Modulation transfer functions, Chest, X-ray detectors, Signal detection

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Proceedings Article | 18 December 2003 Paper

ISO 20462: a psychophysical image quality measurement standard

Brian Keelan, Hitoshi Urabe

Proceedings Volume 5294, (2003) https://doi.org/10.1117/12.532064

KEYWORDS: Image quality, Standards development, Image quality standards, Steiner quadruple pulse system, Calibration, Modulation transfer functions, Quality measurement, Binary data, Electronic imaging, Statistical analysis

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Showing 5 of 16 publications

Course Instructor

SC593: Characterization and Prediction of Image Quality

This course explains how to evaluate the quality of an image using numerical scales and physical standards; and how to predict the distribution of quality that would be produced by a pictorial imaging system under conditions of actual customer use. A framework is presented for conducting calibrated, extensible psychometric research so that results from different experiments can be rigorously integrated to construct predictive software using Monte Carlo simulations. Development of generalized objective metrics correlating with perceptual attributes based on psychometric data is discussed in detail and a number of examples of practical applications to product design are provided.

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