Publications de Emrah Bostan | EPFL Graph Search

Variations of intracellular density during the cell cycle arise from tip-growth regulation in fission yeast

Intracellular density impacts the physical nature of the cytoplasm and can globally affect cellular processes, yet density regulation remains poorly understood. Here, using a new quantitative phase imaging method, we determined that dry-mass density in fis ...

ELIFE SCIENCES PUBLICATIONS LTD2021

Combined Multi-Plane Tomographic Phase Retrieval and Stochastic Optical Fluctuation Imaging for 4D Cell Microscopy

Theo Lasser, Hilal Lashuel, Anne-Laure Mahul Mellier, Marcel Leutenegger, Emrah Bostan, Arno Pino Bouwens, Tomas Lukes, Adrien Charles-François Raymond Descloux

Super-resolution fluorescence microscopy provides unprecedented insight into cellular and subcellular structures. However, going beyond the diffraction barrier comes at a price since most far-field super-resolution imaging techniques trade temporal for spa ...

Nature Publishing Group2018

Learning Convex Regularizers for Optimal Bayesian Denoising

Michaël Unser, Emrah Bostan, Quy Ha Nguyen

2018

MMSE Denoising of Sparse and Non-Gaussian AR(1) Processes

Michaël Unser, Emrah Bostan, Pedram Pad, Pouria Tohidi

We propose two minimum-mean-square-error (MMSE) estimation methods for denoising non-Gaussian first-order autoregressive (AR(1)) processes. The first one is based on the message passing framework and gives the exact theoretic MMSE estimator. The second is ...

IEEE2016

Variational Phase Imaging Using the Transport-of-Intensity Equation

Michaël Unser, Daniel Sage, Emrah Bostan, Masih Nilchian, Emmanuel Augustin Julien Froustey

We introduce a variational phase retrieval algorithm for the imaging of transparent objects. Our formalism is based on the transport-of-intensity equation (TIE), which relates the phase of an optical field to the variation of its intensity along the direct ...

IEEE2016

Joint absorption and phase retrieval in grating-based x-ray radiography

Michaël Unser, Masih Nilchian, Emrah Bostan, Marco Stampanoni, Mohammad Reza Nilchiyan

Given the raw absorption and differential phase-contrast images obtained from a grating-based x-ray radiography, we formulate the joint denoising of the absorption image and retrieval of the non-differential phase image as a regularized inverse problem. Th ...

Optical Society of America2016

Sparsity-Based Data Reconstruction Models for Biomedical Imaging

Emrah Bostan

We propose new regularization models to solve inverse problems encountered in biomedical imaging applications. In formulating mathematical schemes, we base our approach on the sparse signal processing principles that have emerged as a central paradigm in t ...

EPFL2016

Divergence-Free Wavelet Frames

Michaël Unser, Emrah Bostan, John Paul Ward

We propose an efficient construction of wavelet frames in any number of dimensions that are divergence-free. Our approach is based on applying the Leray projector, which is scale-invariant, to a standard wavelet frame. We prove that the projected wavelets ...

IEEE Institute of Electrical and Electronics Engineers2015

Wavelet Statistics of Sparse and Self-Similar Images

Michaël Unser, Emrah Bostan, Julien René Pierre Fageot

It is well documented that natural images are compressible in wavelet bases and tend to exhibit fractal properties. In this paper, we investigate statistical models that mimic these behaviors. We then use our models to make predictions on the statistics of ...

Siam Publications2015

Improved Variational Denoising of Flow Fields with Application to Phase-Contrast MRI Data

Michaël Unser, Nikolaos Stergiopoulos, Emrah Bostan, Orestis Vardoulis, Stamatios Lefkimmiatis

We propose a new variational framework for the problem of reconstructing flow fields from noisy measurements. The formalism is based on regularizers penalizing the singular values of the Jacobian of the field. Specifically, we rely on the nuclear norm. Our ...

IEEE Institute of Electrical and Electronics Engineers2015