The Experts below are selected from a list of 57945 Experts worldwide ranked by ideXlab platform
Jonathan C Horton - One of the best experts on this subject based on the ideXlab platform.
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vertical optokinetic stimulation induces diagonal eye movements in patients with idiopathic infantile nystagmus
Investigative Ophthalmology & Visual Science, 2020Co-Authors: John R Economides, Young Woo Suh, Joshua B Simmons, Daniel L Adams, Jonathan C HortonAbstract:Author(s): Economides, John R; Suh, Young-Woo; Simmons, Joshua B; Adams, Daniel L; Horton, Jonathan C | Abstract: Purpose:In patients with early ocular misalignment and nystagmus, vertical optokinetic stimulation reportedly increases the horizontal component of the nystagmus present during fixation, resulting in diagonal eye movements. We tested patients with infantile nystagmus syndrome but normal ocular alignment to determine if this crosstalk depends on strabismus. Methods:Eye movements were recorded in seven patients with infantile nystagmus. All but one patient had normal ocular alignment with high-grade stereopsis. Nystagmus during interleaved trials of right, left, up, and down optokinetic stimulation was compared with waveforms recorded during fixation. Six patients with strabismus but no nystagmus were also tested. Results:In infantile nystagmus syndrome, horizontal motion evoked a mostly jerk nystagmus with virtually no vertical component. A vertical optokinetic Pattern produced nystagmus with a diagonal trajectory. It was not simply a combination of a vertical component from optokinetic stimulation and a horizontal component from the subject's congenital nystagmus, rather in six of seven patients, the slow-phase velocity of the horizontal component during vertical optokinetic stimulation differed from that recorded during fixation. In the six strabismus patients without nystagmus, responses to vertical optokinetic stimulation were normal. Conclusions:In patients with congenital motor nystagmus, a vertical Noise Pattern drives a diagonal nystagmus. This appears to arise because of crosstalk between the vertical and horizontal components of the optokinetic system. This abnormal response to vertical stimulation is not caused by strabismus because it occurs in patients with infantile nystagmus without strabismus. Moreover, it is absent in patients with strabismus and no spontaneous nystagmus.
Nasir Memon - One of the best experts on this subject based on the ideXlab platform.
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analysis of seam carving based anonymization of images against prnu Noise Pattern based source attribution
IEEE Transactions on Information Forensics and Security, 2014Co-Authors: Ahmet Emir Dirik, Husrev T Sencar, Nasir MemonAbstract:The availability of sophisticated source attribution techniques raises new concerns about privacy and anonymity of photographers, activists, and human right defenders who need to stay anonymous while spreading their images and videos. Recently, the use of seam-carving, a content-aware resizing method, has been proposed to anonymize the source camera of images against the well-known photoresponse nonuniformity (PRNU)-based source attribution technique. In this paper, we provide an analysis of the seam-carving-based source camera anonymization method by determining the limits of its performance introducing two adversarial models. Our analysis shows that the effectiveness of the deanonymization attacks depend on various factors that include the parameters of the seam-carving method, strength of the PRNU Noise Pattern of the camera, and an adversary’s ability to identify uncarved image blocks in a seam-carved image. Our results show that, for the general case, there should not be many uncarved blocks larger than the size of $50\times 50$ pixels for successful anonymization of the source camera.
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seam carving based anonymization against image video source attribution
Multimedia Signal Processing, 2013Co-Authors: Sevinc Bayram, Husrev T Sencar, Nasir MemonAbstract:As image source attribution techniques have become significantly sophisticated and are now becoming commonplace, there is a growing need for capabilities to anonymize images and videos. Focusing on the photo response non-uniformity Noise Pattern based sensor fingerprinting technique, this work evaluates the effectiveness of well-established seam carving method to defend against sensor fingerprint matching. We consider ways in which seam-carving based anonymization can be countered and propose enhancements over conventional seam carving method. Our results show that applying geometrical distortion in addition to seam carving will make counter attack very ineffective both in terms of computational complexity and accuracy.
John R Economides - One of the best experts on this subject based on the ideXlab platform.
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vertical optokinetic stimulation induces diagonal eye movements in patients with idiopathic infantile nystagmus
Investigative Ophthalmology & Visual Science, 2020Co-Authors: John R Economides, Young Woo Suh, Joshua B Simmons, Daniel L Adams, Jonathan C HortonAbstract:Author(s): Economides, John R; Suh, Young-Woo; Simmons, Joshua B; Adams, Daniel L; Horton, Jonathan C | Abstract: Purpose:In patients with early ocular misalignment and nystagmus, vertical optokinetic stimulation reportedly increases the horizontal component of the nystagmus present during fixation, resulting in diagonal eye movements. We tested patients with infantile nystagmus syndrome but normal ocular alignment to determine if this crosstalk depends on strabismus. Methods:Eye movements were recorded in seven patients with infantile nystagmus. All but one patient had normal ocular alignment with high-grade stereopsis. Nystagmus during interleaved trials of right, left, up, and down optokinetic stimulation was compared with waveforms recorded during fixation. Six patients with strabismus but no nystagmus were also tested. Results:In infantile nystagmus syndrome, horizontal motion evoked a mostly jerk nystagmus with virtually no vertical component. A vertical optokinetic Pattern produced nystagmus with a diagonal trajectory. It was not simply a combination of a vertical component from optokinetic stimulation and a horizontal component from the subject's congenital nystagmus, rather in six of seven patients, the slow-phase velocity of the horizontal component during vertical optokinetic stimulation differed from that recorded during fixation. In the six strabismus patients without nystagmus, responses to vertical optokinetic stimulation were normal. Conclusions:In patients with congenital motor nystagmus, a vertical Noise Pattern drives a diagonal nystagmus. This appears to arise because of crosstalk between the vertical and horizontal components of the optokinetic system. This abnormal response to vertical stimulation is not caused by strabismus because it occurs in patients with infantile nystagmus without strabismus. Moreover, it is absent in patients with strabismus and no spontaneous nystagmus.
Rainer Böhme - One of the best experts on this subject based on the ideXlab platform.
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The Dresden Image Database for Benchmarking Digital Image Forensics
Journal of Digital Forensic Practice, 2010Co-Authors: Thomas Gloe, Rainer BöhmeAbstract:ABSTRACT This article introduces and documents a novel image database specifically built for the purpose of development and benchmarking of camera-based digital forensic techniques. More than 14,000 images of various indoor and outdoor scenes have been acquired under controlled and thus widely comparable conditions from altogether 73 digital cameras. The cameras were drawn from only 25 different models to ensure that device-specific and model-specific characteristics can be disentangled and studied separately, as validated with results in this article. In addition, auxiliary images for the estimation of device-specific sensor Noise Pattern were collected for each camera. Another subset of images to study model-specific JPEG compression algorithms has been compiled for each model. The Dresden Image Database is freely available for scientific purposes. The database is intended to become a useful resource for researchers and forensic investigators. Using a standard database as a benchmark makes results more ...
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the dresden image database for benchmarking digital image forensics
ACM Symposium on Applied Computing, 2010Co-Authors: Thomas Gloe, Rainer BöhmeAbstract:This paper introduces and documents a novel image database specifically built for the purpose of development and bench-marking of camera-based digital forensic techniques. More than 14,000 images of various indoor and outdoor scenes have been acquired under controlled and thus widely comparable conditions from altogether 73 digital cameras. The cameras were drawn from only 25 different models to ensure that device-specific and model-specific characteristics can be disentangled and studied separately, as validated with results in this paper. In addition, auxiliary images for the estimation of device-specific sensor Noise Pattern were collected for each camera. Another subset of images to study model-specific JPEG compression algorithms has been compiled for each model. The 'Dresden Image Database' will be made freely available for scientific purposes when this accompanying paper is presented. The database is intended to become a useful resource for researchers and forensic investigators. Using a standard database as a benchmark not only makes results more comparable and reproducible, but it is also more economical and avoids potential copyright and privacy issues that go along with self-sampled benchmark sets from public photo communities on the Internet.
Daniel L Adams - One of the best experts on this subject based on the ideXlab platform.
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vertical optokinetic stimulation induces diagonal eye movements in patients with idiopathic infantile nystagmus
Investigative Ophthalmology & Visual Science, 2020Co-Authors: John R Economides, Young Woo Suh, Joshua B Simmons, Daniel L Adams, Jonathan C HortonAbstract:Author(s): Economides, John R; Suh, Young-Woo; Simmons, Joshua B; Adams, Daniel L; Horton, Jonathan C | Abstract: Purpose:In patients with early ocular misalignment and nystagmus, vertical optokinetic stimulation reportedly increases the horizontal component of the nystagmus present during fixation, resulting in diagonal eye movements. We tested patients with infantile nystagmus syndrome but normal ocular alignment to determine if this crosstalk depends on strabismus. Methods:Eye movements were recorded in seven patients with infantile nystagmus. All but one patient had normal ocular alignment with high-grade stereopsis. Nystagmus during interleaved trials of right, left, up, and down optokinetic stimulation was compared with waveforms recorded during fixation. Six patients with strabismus but no nystagmus were also tested. Results:In infantile nystagmus syndrome, horizontal motion evoked a mostly jerk nystagmus with virtually no vertical component. A vertical optokinetic Pattern produced nystagmus with a diagonal trajectory. It was not simply a combination of a vertical component from optokinetic stimulation and a horizontal component from the subject's congenital nystagmus, rather in six of seven patients, the slow-phase velocity of the horizontal component during vertical optokinetic stimulation differed from that recorded during fixation. In the six strabismus patients without nystagmus, responses to vertical optokinetic stimulation were normal. Conclusions:In patients with congenital motor nystagmus, a vertical Noise Pattern drives a diagonal nystagmus. This appears to arise because of crosstalk between the vertical and horizontal components of the optokinetic system. This abnormal response to vertical stimulation is not caused by strabismus because it occurs in patients with infantile nystagmus without strabismus. Moreover, it is absent in patients with strabismus and no spontaneous nystagmus.