2,803 research outputs found
Unsupervised Multi Class Segmentation of 3D Images with Intensity Inhomogeneities
Intensity inhomogeneities in images constitute a considerable challenge in
image segmentation. In this paper we propose a novel biconvex variational model
to tackle this task. We combine a total variation approach for multi class
segmentation with a multiplicative model to handle the inhomogeneities. Our
method assumes that the image intensity is the product of a smoothly varying
part and a component which resembles important image structures such as edges.
Therefore, we penalize in addition to the total variation of the label
assignment matrix a quadratic difference term to cope with the smoothly varying
factor. A critical point of our biconvex functional is computed by a modified
proximal alternating linearized minimization method (PALM). We show that the
assumptions for the convergence of the algorithm are fulfilled by our model.
Various numerical examples demonstrate the very good performance of our method.
Particular attention is paid to the segmentation of 3D FIB tomographical images
which was indeed the motivation of our work
Joint denoising and distortion correction of atomic scale scanning transmission electron microscopy images
Nowadays, modern electron microscopes deliver images at atomic scale. The
precise atomic structure encodes information about material properties. Thus,
an important ingredient in the image analysis is to locate the centers of the
atoms shown in micrographs as precisely as possible. Here, we consider scanning
transmission electron microscopy (STEM), which acquires data in a rastering
pattern, pixel by pixel. Due to this rastering combined with the magnification
to atomic scale, movements of the specimen even at the nanometer scale lead to
random image distortions that make precise atom localization difficult. Given a
series of STEM images, we derive a Bayesian method that jointly estimates the
distortion in each image and reconstructs the underlying atomic grid of the
material by fitting the atom bumps with suitable bump functions. The resulting
highly non-convex minimization problems are solved numerically with a trust
region approach. Well-posedness of the reconstruction method and the model
behavior for faster and faster rastering are investigated using variational
techniques. The performance of the method is finally evaluated on both
synthetic and real experimental data
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