Learn More
We address the task of reconstructing images corrupted by Poisson noise, which is important in various applications, such as fluorescence microscopy, positron emission tomography (PET), or astronomical imaging. In this work, we focus on reconstruction strategies, combining the expectation-maximization (EM) algorithm and total variation (TV) based(More)
In this work we analyze and compare two recent variational models for image denoising and improve their reconstructions by applying a Bregman iteration strategy. One of the standard techniques in image denoising, the ROF-model (cf. Rudin et al. in Phys-ica D 60:259–268, 1992), is well known for recovering sharp edges of a signal or image, but also for(More)
—PET measurements of tracers with a lower dose rate or short radioactive half life suffer from extremely low SNRs. In these cases standard reconstruction methods (OSEM, EM, filtered backprojection) deliver unsatisfactory and noisy results. Here, we propose to introduce nonlinear variational methods into the reconstruction process to make an efficient use of(More)
Measurements in nanoscopic imaging suffer from blurring effects concerning different point spread functions (PSF). Some apparatus even have PSFs that are locally dependent on phase shifts. Additionally , raw data are affected by Poisson noise resulting from laser sampling and "photon counts" in fluorescence microscopy. In these applications standard(More)
Given a graph where vertices represent alternatives and pairwise comparison data, y ij , is given on the edges, the statistical ranking problem is to find a potential function, defined on the vertices, such that the gradient of the potential function agrees with pairwise comparisons. We study the dependence of the statistical ranking problem on the(More)
Results on J== production in ep interactions in the H1 experiment at HERA are presented. The J== mesons are produced by almost real photons (Q 2 0) and detected via their leptonic decays. The data have been taken in 1994 and correspond to an integrated luminosity of 2:7 pb ?1. The p cross section for elastic J== production is observed to increase strongly(More)
Measurements in nanoscopic imaging suffer from blurring effects modeled with different point spread functions (PSF). Some apparatus even have PSFs that are locally dependent on phase shifts. Additionally, raw data are affected by Poisson noise resulting from laser sampling and " photon counts " in fluorescence microscopy. In these applications standard(More)
This paper deals with denoising of density images with bad Poisson statistics (low count rates), where the reconstruction of the major structures seems the only reasonable task. Obtaining the structures with sharp edges can also be a prerequisite for further processing, e.g. segmentation of objects. A variety of approaches exists in the case of Gaussian(More)
  • Bartel, M Barth, U Bassler, H P Beck, H.-J Behrend, A Belousov +108 others
  • 2007
Evidence is presented using data taken with the H1 detector at HERA for a class of deep inelastic electron{proton scattering (DIS) events (5 < Q 2 < 120 GeV 2) at low Bjorken-x (10 ?4 < x < 10 ?2) which have almost no hadronic energy ow in a large interval of pseudo-rapidity around the proton remnant direction and which cannot be attributed to our present(More)
We present a study of J== meson production in collisions of 26:7 GeV electrons with 820 GeV protons, performed with the H1-detector at the HERA collider at DESY. The J== mesons are detected via their leptonic decays both to electrons and muons. Requiring exactly two particles in the detector, a cross section of (ep ! J==X) = (8:8 2:0 2:2) nb is determined(More)