Hasan Ertan Çetingül

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The mean shift algorithm, which is a nonparametric density estimator for detecting the modes of a distribution on a Euclidean space, was recently extended to operate on analytic manifolds. The extension is extrinsic in the sense that the inherent optimization is performed on the tangent spaces of these manifolds. This approach specifically requires the use(More)
There have been several studies that jointly use audio, lip intensity, and lip geometry information for speaker identification and speech-reading applications. This paper proposes using explicit lip motion information, instead of or in addition to lip intensity and/or geometry information, for speaker identification and speech-reading within a unified(More)
We address the problem of segmenting high angular resolution diffusion imaging (HARDI) data into multiple regions (or fiber tracts) with distinct diffusion properties. We use the orientation distribution function (ODF) to model diffusion and cast the ODF segmentation problem as a clustering problem in the space of ODFs. Our approach integrates tools from(More)
We present a new multimodal speaker/speech recognition system that integrates audio, lip texture and lip motion modalities. Fusion of audio and face texture modalities has been investigated in the literature before. The emphasis of this work is to investigate the benefits of inclusion of lip motion modality for two distinct cases: speaker and speech(More)
This paper addresses the selection of best lip motion features for biometric open-set speaker identification. The best features are those that result in the highest discrimination of individual speakers in a population. We first detect the face region in each video frame. The lip region for each frame is then segmented following registration of successive(More)
Reducing the amount of information stored in diffusion MRI (dMRI) data to a set of meaningful and representative scalar values is a goal of much interest in medical imaging. Such features can have far reaching applications in segmentation, registration, and statistical characterization of regions of interest in the brain, as in comparing features between(More)
This paper addresses the selection of robust lip-motion features for audio-visual open-set speaker identification problem. We consider two alternatives for initial lip motion representation. In the first alternative, the feature vector is composed of the 2D-DCT coefficients of the motion vectors estimated within the detected rectangular mouth region whereas(More)
We consider the problem of processing high angular resolution diffusion images described by orientation distribution functions (ODFs). Prior work showed that several processing operations, e.g., averaging, interpolation and filtering, can be reduced to averaging in the space of ODFs. However, this approach leads to anatomically erroneous results when the(More)
This paper presents a stochastic tractography algorithm to identify branching fibrous structures in 3-D images. Specifically, we employ a Bayesian formulation that involves sequential importance resampling of multiple fiber trajectories (particles). At each step, we sample local orientation candidates from a discrete importance density that is estimated by(More)