Stefan Winkler

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In this paper, we present a no-reference blur metric for images and video. The blur metric is based on the analysis of the spread of the edges in an image. Its perceptual significance is validated through subjective experiments. The novel metric is near real-time, has low computational complexity and is shown to perform well over a range of image content.(More)
We present a fulland no-reference blur metric as well as a full-reference ringing metric. These metrics are based on an analysis of the edges and adjacent regions in an image and have very low computational complexity. As blur and ringing are typical artifacts of wavelet compression, the metrics are then applied to JPEG2000 coded images. Their perceptual(More)
Large face datasets are important for advancing face recognition research, but they are tedious to build, because a lot of work has to go into cleaning the huge amount of raw data. To facilitate this task, we describe an approach to building face datasets that starts with detecting faces in images returned from searches for public figures on the Internet,(More)
Tektronix Inc., Beaverton, Oregon; Communications Research Centre, Ottawa, Canada; National Institute of Standards and Technology, Gaithersburg, Maryland; U.S. Dept. of Commerce, Boulder, Colorado; Fondazione Ugo Bordoni, Rome, Italy; KPN Research, Leidschendam, Netherlands; CCETT/CNET, Sévigné Cedex, France; Centro Studi e Laboratori Telecomunicazioni,(More)
Databases of images or videos annotated with subjective ratings constitute essential ground truth for training, testing, and benchmarking algorithms for objective quality assessment. More than two dozen such databases are now available in the public domain; they are presented and analyzed in this paper. We propose several criteria for quantitative(More)
In this paper I present a distortion metric for color video sequences. It is based on a contrast gain control model of the human visual system that incorporates spatial and temporal aspects of vision as well as color perception. The model achieves a close fit to contrast sensitivity and contrast masking data from several different psychophysical experiments(More)
This paper presents the techniques employed in our team's submissions to the 2015 Emotion Recognition in the Wild contest, for the sub-challenge of Static Facial Expression Recognition in the Wild. The objective of this sub-challenge is to classify the emotions expressed by the primary human subject in static images extracted from movies. We follow a(More)
In this paper, investigations are conducted to simplify and re ne a vision model based video quality metric without compromising its prediction accuracy. Unlike other vision model based quality metrics, the proposed metric is parameterized using subjective quality assessment data recently provided by the Video Quality Experts Group (VQEG). The quality(More)
Color image quality depends on many factors, such as the initial capture system and its color image processing, compression, transmission, the output device, media and associated viewing conditions. In this paper, we are primarily concerned with color image quality in relation to compression and transmission. We review the typical visual artifacts that(More)