Publications de Chandra Sekhar Seelamantula

HILBERT TRANSFORM RELATIONS IN FREQUENCY-DOMAIN OPTICAL-COHERENCE TOMOGRAPHIC IMAGING

Theo Lasser, Chandra Sekhar Seelamantula

Interferometric imaging techniques typically embed the object phase information in the magnitude during the measurement process. During reconstruction, the phase is recovered from the magnitude by certain approximations on the measured magnitude and underl ...

2013

A Shape-Template Based Two-Stage Corpus Callosum Segmentation Technique for Sagittal Plane T1-Weighted Brain Magnetic Resonance Images

Michaël Unser, Chandra Sekhar Seelamantula

We propose a semi-automatic technique to segment corpus callosum (CC) using a two-stage snake formulation: A restricted affine transform (RAT) constrained snake followed by an unconstrained snake in an iterative fashion. A statistical model is developed to ...

IEEE2013

Zero-crossing approach to high-resolution reconstruction in frequency-domain optical-coherence tomography

Theo Lasser, Marcel Leutenegger, Arno Pino Bouwens, Chandra Sekhar Seelamantula

We address the problem of high-resolution reconstruction in frequency-domain optical-coherence tomography (FDOCT). The traditional method employed uses the inverse discrete Fourier transform, which is limited in resolution due to the Heisenberg uncertainty ...

2012

Snakes With an Ellipse-Reproducing Property

Michaël Unser, Philippe Thévenaz, Chandra Sekhar Seelamantula, Ricard Delgado Gonzalo

We present a new class of continuously defined parametric snakes using a special kind of exponential splines as basis functions. We have enforced our bases to have the shortest possible support subject to some design constraints to maximize efficiency. Whi ...

IEEE2012

Local demodulation of holograms using the Riesz transform with application to microscopy

Michaël Unser, Christian Depeursinge, Nicolas Pavillon, Chandra Sekhar Seelamantula

We propose a Riesz transform approach to the demodulation of digital holograms. The Riesz transform is a higher-dimensional extension of the Hilbert transform and is steerable to a desired orientation. Accurate demodulation of the hologram requires a relia ...

Optical Society of America2012

Exact Complex-Wave Reconstruction in Digital Holography

Michaël Unser, Christian Depeursinge, Nicolas Pavillon, Chandra Sekhar Seelamantula

We address the problem of exact complex-wave reconstruction in digital holography. We show that, by confining the object-wave modulation to one quadrant of the frequency domain, and by maintaining a reference-wave intensity higher than that of the object, ...

OSA2011

A method and apparatus for enhanced spatial bandwidth wavefronts reconstructed from digital interferograms or holograms

Michaël Unser, Christian Depeursinge, Nicolas Pavillon, Chandra Sekhar Seelamantula

The present invention discloses a method and an apparatus to compute a complex wavefield, referred to as the object wave o, by means of measuring the intensity signal resulting from the interference of the said object wave with a second wave termed the ref ...

2010

A fast time-domain algorithm for the assessment of tissue blood flow in laser-Doppler flowmetry

Dimitri Nestor Alice Van De Ville, Chandra Sekhar Seelamantula

In this study, we derive a fast, novel time-domain algorithm to compute the nth-order moment of the power spectral density of the photoelectric current as measured in laser-Doppler flowmetry (LDF). It is well established that in the LDF literature these mo ...

Institute of Physics2010

A Time-Domain Wavelet-Based Approach for Fluorescence Diffuse Optical Tomography

Michaël Unser, Chandra Sekhar Seelamantula

Purpose: In the context of fluorescence diffuse optical tomography, determining the optimal way to exploit the time-resolved information has been receiving much attention and different features of the time-resolved signals have been introduced. In this art ...

AAPM2010

Performance Analysis of Reconstruction Techniques for Frequency-Domain Optical-Coherence Tomography

Michaël Unser, Chandra Sekhar Seelamantula

We address the issue of noise robustness of reconstruction techniques for frequency-domain optical-coherence tomography (FDOCT). We consider three reconstruction techniques: Fourier, iterative phase recovery, and cepstral techniques. We characterize the re ...

Institute of Electrical and Electronics Engineers2010