@article {uttenweiler2003a, title = {Spatiotemporal anisotropic diffusion filtering to improve signal-to-noise ratios and object restoration in fluorescence microscopic image sequences.}, journal = {J Biomed Opt}, volume = {8}, number = {1}, year = {2003}, pages = {40--47}, publisher = {Ruprecht-Karls-Universit{\"a}t Heidelberg, Institut f{\"u}r Physiologie und Pathophysiologie Medical Biophysics, Im Neuenheimer Feld 326, 69120 Heidelberg, Germany. dietmar.uttenweiler@urz.uni-heidelberg.de}, abstract = {We present an approach for significantly improving the quantitative analysis of motion in noisy fluorescence microscopic image sequences. The new partial differential equation based method is a general extension of a 2-D nonlinear anisotropic diffusion filtering scheme to a specially adapted 3D nonlinear anisotropic diffusion filtering scheme, with two spatial image dimensions and the time t in the image sequence as the third dimension. Motion in image sequences is considered as oriented, line-like structures in the spatiotemporal x,y,t domain, which are determined by the structure tensor method. Image enhancement is achieved by a structure adopted smoothing kernel in three dimensions, thereby using the full 3D information inherent in spatiotemporal image sequences. As an example for low signal-to-noise ratio (SNR) microscopic image sequences we have applied this method to noisy in vitro motility assay data, where fluorescently labeled actin filaments move over a surface of immobilized myosin. With the 3D anisotropic diffusion filtering the SNR is significantly improved (by a factor of 3.8) and closed object structures are reliably restored, which were originally degraded by noise. Generally, this approach is very valuable for all applications where motion has to be measured quantitatively in low light level fluorescence microscopic image sequences of cellular, subcellular, and molecular processes.}, doi = {10.1117/1.1527627}, url = {http://dx.doi.org/10.1117/1.1527627}, author = {D. Uttenweiler and C. Weber and Bernd J{\"a}hne and Rainer H. A. Fink and Schaar, H.} } @conference {raisch2002, title = {Velocity and feature estimation of actin filaments using active contours in noisy fluorescence image sequences}, booktitle = {Proc. 2nd IASTED Int. Conf. Visualization, Imaging and Image Processing}, year = {2002}, pages = {645--650}, abstract = {We present a new approach for determining particle fea tures such as length, curvature and hence flexibility in addition to the velocity of moving single actin filaments in noisy fluorescence image sequences. The reliable deter mination of these features is essential for the analysis of the elementary force generation process of single motor molecules including heart and skeletal muscle myosins. First, the image sequence is preprocessed with the 3D structure tensor - where the third dimension is the time t in the image sequence - in order to eliminate noise and to obtain a measure for extracting coherently moving par ticles. Secondly, we determine the contour of the actin filaments with subpixel accuracy using active contours. Thereafter, we readjust a local coordinate system to elim inate inner movements of the active contour. In the fourth step, we estimate the initial position of the active contour in the next frame from the displacement vector field cal culated by the 3D structure tensor. The accuracy of the method is verified on synthetic test data, a prerequisite for the quantitative use of this method on experimentally obtained data. Finally this is demonstrated for fluorescence image sequences of actin filament movement in the in vitro motility assay.}, author = {Florian Raisch and Hanno Scharr and Norbert Kirchge{\ss}ner and Bernd J{\"a}hne and Rainer H. A. Fink and D. Uttenweiler} } @article {uttenweiler2000, title = {Motion determination in actin filament fluorescence images with a spatio-temporal orientation analysis method.}, journal = {Biophys J}, volume = {78}, number = {5}, year = {2000}, pages = {2709--2715}, publisher = {Institut f{\"u}r Physiologie und Pathophysiologie, Ruprecht-Karls-Universit{\"a}t Heidelberg, 69120 Heidelberg, Germany. uttenweiler@urz.uni-heidelberg.de}, abstract = {We present a novel approach of automatically measuring motion in series of microscopic fluorescence images. As a differential method, the three-dimensional structure tensor technique is used to calculate the displacement vector field for every image of the sequence, from which the velocities are subsequently derived. We have used this method for the analysis of the movement of single actin filaments in the in vitro motility assay, where fluorescently labeled actin filaments move over a myosin decorated surface. With its fast implementation and subpixel accuracy, this approach is, in general, very valuable for analyzing dynamic processes by image sequence analysis.}, doi = {10.1016/S0006-3495(00)76815-9}, author = {D. Uttenweiler and C. Veigel and R. Steubing and Carlo G{\"o}tz and Sven Mann and Horst Hau{\ss}ecker and Bernd J{\"a}hne and Rainer H. A. Fink} }