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- Johnathan M. Bardsley, Aaron Luttman
- Adv. Comput. Math.
- 2009

The noise contained in data measured by imaging instruments is often primarily of Poisson type. This motivates, in many cases, the use of the Poisson negative-log likelihood function in place of the ubiquitous least squares data fidelity when solving image deblurring problems. We assume that the underlying blurring operator is compact, so that, as in the… (More)

In image processing applications, image intensity is often measured via the counting of incident photons emitted by the object of interest. In such cases, image data-noise is accurately modeled by a Poisson distribution. This motivates the use of Poisson maximum likelihood estimation for image reconstruction. However, when the underlying model equation is… (More)

- Johnathan M. Bardsley
- SIAM J. Scientific Computing
- 2012

The connection between Bayesian statistics and the technique of regularization for inverse problems has been given significant attention in recent years. For example, Bayes' Law is frequently used as motivation for variational regularization methods of Tikhonov type. In this setting , the regularization function corresponds to the negative-log of the prior… (More)

SUMMARY The standard formulations of the Kalman filter (KF) and extended Kalman filter (EKF) require storing and multiplication of matrices of size n × n, where n is the size of the state space, and the inversion of matrices of size m × m, where m is the size of the observation space. For large dimensions implementation issues arise. In this paper we… (More)

- Johnathan M. Bardsley, Antti Solonen, Heikki Haario, Marko Laine
- SIAM J. Scientific Computing
- 2014

Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Abstract. High-dimensional inverse problems present a challenge for Markov… (More)

—The data in PET emission and transmission tomog-raphy and in low dose X-ray tomography, consists of counts of photons originating from random events. The need to model the data as a Poisson process poses a challenge for traditional integral geometry-based reconstruction algorithms. Although qualitative a priori information of the target may be available,… (More)

- Johnathan M. Bardsley, Curtis R. Vogel
- SIAM J. Scientific Computing
- 2004

We consider a large-scale convex minimization problem with nonnegativity constraints that arises in astronomical imaging. We develop a cost functional which incorporates the statistics of the noise in the image data and Tikhonov regularization to induce stability. We introduce an efficient hybrid gradient projection-reduced Newton (active set) method. By "… (More)

- Johnathan M. Bardsley, James G. Nagy
- SIAM J. Matrix Analysis Applications
- 2006

We consider the problem of solving ill-conditioned linear systems Ax = b subject to the nonnegativity constraint x ≥ 0, and in which the vector b is a realization of a random vectorˆb, i.e. b is noisy. We explore what the statistical literature tells us about solving noisy linear systems; we discuss the effect that a substantial black background in the… (More)

- Johnathan M Bardsley
- Journal of the Optical Society of America. A…
- 2004

Image reconstruction gives rise to some challenging large-scale constrained optimization problems. We consider a convex minimization problem with nonnegativity constraints that arises in astronomical imaging. To solve this problem, we use an efficient hybrid gradient projection-reduced Newton (active-set) method. By "reduced Newton," we mean that we take… (More)

- Johnathan Bardsley, Stuart Jefferies, James Nagy, Robert Plemmons
- Optics express
- 2006

In this paper, we present an algorithm for the restoration of images with an unknown, spatially-varying blur. Existing computational methods for image restoration require the assumption that the blur is known and/or spatially-invariant. Our algorithm uses a combination of techniques. First, we section the image, and then treat the sections as a sequence of… (More)