Browsing by Author "Onural, L."
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3D motion estimation and wireframe adaptation including photometric effects for modelbased coding of facial image sequences
Bozdağı, G.; Tekalp, A. M.; Onural, L. (IEEE, 199406)We propose a novel formulation where 3D global and local motion estimation and the adaptation of a generic wireframe model to a particular speaker are considered simultaneously within an optical flow based framework ... 
3D motion estimation of rigid objects for video coding applications using an improved iterative version of the Ematrix method
Alatan, A. A.; Onural, L. (Institute of Electrical and Electronics Engineers, 199802)As an alternative to current twodimensional (2D) motion models, a robust threedimensional (3D) motion estimation method is proposed to be utilized in objectbased video coding applications. Since the popular Ematrix ... 
3D model compression using connectivityguided adaptive wavelet transform built into 2D SPIHT
Köse K.; Çetin, A. Enis; Güdükbay, Uğur; Onural, L. (Academic Press, 201001)ConnectivityGuided Adaptive Wavelet Transform based mesh compression framework is proposed. The transformation uses the connectivity information of the 3D model to exploit the interpixel correlations. Orthographic ... 
3DTV: Capture, transmission, and Display of 3D Video
Triantafyllidis, G. A.; Çetin, A. Enis; Smolic, A.; Onural, L.; Sikora, T.; Watson, J. (2009)[No abstract available] 
A aurvey of signal processing problems and tools in holographic threedimensional television
Onural, L.; Gotchev, A.; Özaktaş, Haldun M.; Stoykova, E. (Institute of Electrical and Electronics Engineers, 2007)Diffraction and holography are fertile areas for application of signal theory and processing. Recent work on 3DTV displays has posed particularly challenging signal processing problems. Various procedures to compute ... 
Calculation of the scalar diffraction field from curved surfaces by decomposing the threedimensional field into a sum of Gaussian beams
Şahin, E.; Onural, L. (Optical Society of America, 2013)We present a local Gaussian beam decomposition method for calculating the scalar diffraction field due to a twodimensional field specified on a curved surface. We write the threedimensional field as a sum of Gaussian beams ... 
Circular holographic video display system
Yaraş, F.; Kang, H.; Onural, L. (Optical Society of American (OSA), 2011)A circular holographic video display system reconstructs holographic video. Phaseonly spatial light modulators are tiled in a circular configuration in order to increase the field of view. A beamsplitter is used to align ... 
A class of adaptive directional image smoothing filters
Gürelli, M. İ.; Onural, L. (Elsevier BV, 199612)The gray level distribution around a pixel of an image usually tends to be more coherent in some directions compared to other directions. The idea of adaptive directional filtering is to estimate the direction of higher ... 
A comparative study of light field representation and integral imaging
Sahin, E.; Onural, L. (Taylor and Francis, 20130718)Light field representation is a model for threedimensional (3D) image representation and integral imaging is an optical 3D imaging and representation method. A comparative investigation of light field representation and ... 
Convolution, filtering, and multiplexing in fractional Fourier domains and their relation to chirp and wavelet transforms
Özaktaş, Haldun M.; Barshan, B.; Mendlovic, D.; Onural, L. (1994)A concise introduction to the concept of fractional Fourier transforms is followed by a discussion of their relation to chirp and wavelet transforms. The notion of fractional Fourier domains is developed in conjunction ... 
Design and implementation of a generalpurpose median filter unit in CMOS VLSI
Karaman, M.; Onural, L.; Atalar, Abdullah (IEEE SolidState Circuits Society, 1990)A generalpurpose median filter unit configuration is proposed in the form of two singlechip median filters, one extensible and one realtime. The networks of the chips are pipelined and systolic at bit level and based ... 
Diffraction field computation from arbitrarily distributed data points in space
Esmer, G. B.; Uzunov, V.; Onural, L.; Özaktaş, Haldun M.; Gotchev, A. (Elsevier BV, 200702)Computation of the diffraction field from a given set of arbitrarily distributed data points in space is an important signal processing problem arising in digital holographic 3D displays. The field arising from such ... 
Diffraction from a wavelet point of view
Onural, L. (Optical Society of America, 19930601)The system impulse response representing the Fresnel diffraction is shown to form a wavelet family of functions. The scale parameter of the wavelet family represents the depth (distance). This observation relates ... 
Digital decoding of inline holograms
Onural, L.; Scott, P. D. (SPIE, 1987)Digitally sampled inline holograms may be linearly filtered to reconstruct a representation of the original object distribution, thereby decoding the information contained in the hologram. The decoding process is performed ... 
Digital holographic threedimensional video displays
Onural, L.; Yaras, F.; Kang, H. (IEEE, 20110204)Holography aims to record and regenerate volume filling light fields to reproduce ghostlike 3D images that are optically indistinguishable from their physical 3D originals. Digital holographic video displays are pixelated ... 
Estimation of depth fields suitable for video compression based on 3D structure and motion of objects
Alatan, A. A.; Onural, L. (Institute of Electrical and Electronics Engineers, 199806)Intensity prediction along motion trajectories removes temporal redundancy considerably in video compression algorithms. In threedimensional (3D) objectbased video coding, both 3D motion and depth values are required ... 
Evaluation of the validity of the scalar approximation in optical wave propagation using a systems approach and an accurate digital electromagnetic model
Kulce, O.; Onural, L.; Özaktaş, Haldun M. (Taylor and Francis Ltd., 2016)The cause and amount of error arising from the use of the scalar approximation in monochromatic optical wave propagation are discussed using a signals and systems formulation. Based on Gauss’s Law, the longitudinal component ... 
Exact analysis of the effects of sampling of the scalar diffraction field
Onural, L. (Optical Society of America, 2007)If the sampled diffraction pattern due to a planar object is used to reconstruct the object pattern by backpropagation, the obtained pattern is no longer the same as the original. The effect of such sampling on the ... 
Exact diffraction calculation from fields specified over arbitrary curved surfaces
Esmer, G. B.; Onural, L.; Özaktaş, Haldun M. (Elsevier, 20110730)Calculation of the scalar diffraction field over the entire space from a given field over a surface is an important problem in computer generated holography. A straightforward approach to compute the diffraction field from ... 
Exact solution for scalar diffraction between tilted and translated planes using impulse functions over a surface
Onural, L. (Optical Society of America, 20110204)The diffraction relation between a plane and another plane that is both tilted and translated with respect to the first one is revisited. The derivation of the result becomes easier when the impulse function over a surface ...