Rolf‐Rainer Grigat

Hamburg University of Technology

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Co-Authors

Thomas Pralow

Philips (Germany)

André Gooßen

Philips (Germany)

Thorsten Gernoth

Apple (Israel)

Jan Marek Marcinczak

Hamburg University of Technology

Marc Hensel

Philips (Finland)

I. Shdaifat

Hamburg University of Technology

Philipp Urban

Fraunhofer Institute for Computer Graphics Research

H. Siegfried Stiehl

Universität Hamburg

K. Wiehler

Hamburg University of Technology

Christoph Schnörr

Heidelberg University

Cooperative Institutions

Universität Hamburg

Hamburg University of Technology

Deutsches Elektronen-Synchrotron DESY

Center for Free-Electron Laser Science

Philips (Germany)

Philips (Finland)

Max Planck Institute for the Structure and Dynamics of Matter

University of Minnesota

Heidelberg University

Hamburg Centre for Ultrafast Imaging

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A system for audio-visual speech recognition

Interspeech 2022 (2005)

I. Shdaifat Rolf‐Rainer Grigat

Audio visual

Audio mining

10.21437/interspeech.2005-367

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Citations (4)

Pose-robust face recognition using shape-adapted texture features

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2011)

Thorsten Gernoth André Gooßen Rolf‐Rainer Grigat

Unconstrained environments with variable ambient illumination and changes of head pose are still challenging for many face recognition systems. To recognize a person independent of pose, we first fit an active appearance model to a given facial image. Shape information is used to transform the face into a pose-normalized representation. We decompose the transformed face into local regions and extract texture features from these not necessarily rectangular regions using a shape-adapted discrete cosine transform. We show that these features contain sufficient discriminative information to recognize persons across changes in pose. Furthermore, our experimental results show a significant improvement in face recognition performance on faces with pose variations when compared with a block-DCT based feature extraction technique in an access control scenario.

Discriminative model

Three-dimensional face recognition

Texture (cosmology)

Feature (linguistics)

10.1117/12.872535

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Recognition of the German Visemes Using Multiple Feature Matching

Lecture notes in computer science (2001)

I. Shdaifat Rolf‐Rainer Grigat Stefan Lütgert

Feature (linguistics)

10.1007/3-540-45404-7_58

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Citations (1)

A System for Automatic Lip Reading.

AVSP (2003)

I. Shdaifat Rolf‐Rainer Grigat D. Langmann

Source

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Citations (3)

Pencil Mouse: Real-Time Estimation of 6-D Pose, Position, and Motion Parameters from a Monocular View

I. Shdaifat Rolf‐Rainer Grigat

Monocular

Pencil (optics)

Position (finance)

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Illumination flicker frequency classification in rolling shutter camera systems

IEEE International Conference on Signal and Image Processing (2007)

Touraj Tajbakhsh Rolf‐Rainer Grigat

In many modern imagers employing CMOS pixel arrays the optical integration time is controlled by a rolling shutter. This integration technique, combined with fluorescent illuminators exhibiting an alternating light intensity, causes spatial flicker in images. This flicker can be avoided when the integration time of the imager is adjusted to a multiple of the flicker period. Since the flicker frequency can vary upon the local AC power frequency, a classification must be performed beforehand. This is either performed utilizing an additional illumination intensity detector or, in the case we focus on, restricting to image information only. In this paper we review the state of the art techniques of flicker frequency classification and flicker correction, and propose two robust classification methods based on a clear mathematical model of the illumination flicker problem. We present our simulation results with synthesized image series under different illumination frequencies and shutter widths, whereas our approaches classify robustly in most imaging situations.

Rolling shutter

Flicker fusion threshold

Source

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Citations (3)

Structure from Motion Based Approaches to 3D Reconstruction in Minimal Invasive Laparoscopy

Lecture notes in computer science (2012)

Andres Marmol Jan Marek Marcinczak Rolf‐Rainer Grigat

Bundle adjustment

Ground truth

Lookup table

Surface reconstruction

Structure from Motion

Parametrization (atmospheric modeling)

10.1007/978-3-642-31298-4_35

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Citations (4)

Combined Demosaicing and Adaptive Filtering on CFA Images

Touraj Tajbakhsh Rolf‐Rainer Grigat

The gate-count of Image Signal Processing (ISP) units in digital cameras is significantly dominated by the amount of line buffers utilized by the CFA (Color Filter Array) image interpolation algorithm. Subsequent image filtering on RGB data requires further line buffers for each color channel. We present a local-adaptive Wiener filter for noise cancellation and image enhancement with incorporation of Chang's Variable Number of Gradients interpolation method deploying a 5×5 neighborhood for each pixel. Four line buffers in total are utilized for demosaicing and filtering. Our experimental results indicate a significant increase in SNR whereas edges are preserved and image contrast is enhanced.

Demosaicing

Color filter array

RGB color model

Wiener filter

Interpolation

Bayer filter

Line (geometry)

10.1109/isce.2006.1689422

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Citations (1)

Segmentation of image sequences for object oriented coding

Sven Siggelkow Rolf‐Rainer Grigat Achim Ibenthal

This paper presents an algorithm for segmentation of image sequences where specially aspects for object oriented coding are taken into account. A fundamental requirement of such applications is the temporal stability of the segmentation. This is improved compared to other existing approaches by including motion estimation into the segmentation process. Additionally, a hierarchical approach enables an efficient predictive coding on one hand and a semantic data access on the other hand. As a direct result from using full colour information for the segmentation process, coding of the chrominance information can be done with extremely high compression ratios. Thus there is nearly no extra coding effort for colour images compared to greyscale images.

Chrominance

Segmentation-based object categorization

Predictive coding

10.1109/icip.1996.560892

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Citations (7)

Ruler-Based Automatic Stitching of Spatially Overlapping Radiographs

Informatik aktuell (2008)

André Gooßen Mathias Schlüter Marc Hensel Thomas Pralow Rolf‐Rainer Grigat

Image stitching

Robustness

Feature (linguistics)

10.1007/978-3-540-78640-5_39

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Citations (7)