
Fernando PereiraInstituto Superior Técnico - Universidade de Lisboa
Fernando Pereira
Doctor of Philosophy
About
449
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Introduction
Skills and Expertise
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January 1992 - present
Publications
Publications (449)
Light fields are one of the emerging 3D representation formats with an effective potential to offer very realistic and immersive visual experiences. This capability comes at the cost of a very large amount of acquired data which practical use requires efficient coding solutions. This need was already addressed by the JPEG Pleno Light Field Coding s...
The present invention relates to a prediction-based technique for encoding light field data by removing redundant information of light field data, reducing a number of bits by employing a prediction of a pixel value in all four dimensions of the light field. Using this technique to represent light field data, allows it to be transferred through a l...
Point cloud coding solutions have been recently standardized to address the needs of multiple application scenarios. The design and assessment of point cloud coding methods require reliable objective quality metrics to evaluate the level of degradation introduced by compression or any other type of processing. Several point cloud objective quality...
Point cloud coding solutions have been recently standardized to address the needs of multiple application scenarios. The design and assessment of point cloud coding methods require reliable objective quality metrics to evaluate the level of degradation introduced by compression or any other type of processing. Several point cloud objective quality...
Point cloud coding solutions have been recently standardized to address the needs of multiple application scenarios. The design and assessment of point cloud coding methods require reliable objective quality metrics to evaluate the level of degradation introduced by compression or any other type of processing. Several point cloud objective quality...
Point clouds (PCs) are a powerful 3D visual representation paradigm for many emerging application domains, especially virtual and augmented reality, and autonomous vehicles. However, the large amount of PC data required for highly immersive and realistic experiences requires the availability of efficient, lossy PC coding solutions are critical. Rec...
We present a novel LSTM cell architecture capable of learning both intra- and inter-perspective relationships available in visual sequences captured from multiple perspectives. Our architecture adopts a novel recurrent joint learning strategy that uses additional gates and memories at the cell level. We demonstrate that by using the proposed cell t...
Light field (LF) cameras provide rich spatio-angular visual representations by sensing the visual scene from multiple perspectives and have recently emerged as a promising technology to boost the performance of human-machine systems such as biometrics and affective computing. Despite the significant success of LF representation for constrained faci...
Light field (LF) cameras provide rich spatio-angular visual representations by sensing the visual scene from multiple perspectives and have recently emerged as a promising technology to boost the performance of human-machine systems such as biometrics and affective computing. Despite the significant success of LF representation for constrained faci...
Long Short-Term Memory (LSTM) is a prominent recurrent neural network for extracting dependencies from sequential data such as time-series and multi-view data, having achieved impressive results for different visual recognition tasks. A conventional LSTM network, hereafter referred only as LSTM network, can learn a model to posteriorly extract info...
Recently, point clouds have shown to be a promising way to represent 3D visual data for a wide range of immersive applications, from augmented reality to autonomous cars. Emerging imaging sensors have made it easier to perform richer and denser point cloud acquisition, notably with millions of points, thus raising the need for efficient point cloud...
An increased interest in immersive applications has drawn attention to emerging 3D imaging representation formats, notably light fields and point clouds (PCs). Nowadays, PCs are one of the most popular 3D media formats, due to recent developments in PC acquisition, namely with new depth sensors and signal processing algorithms. To obtain high fidel...
The increasing demand for highly realistic and immersive visual experiences has led to the emergence of richer 3D visual representation models such as light fields, point clouds and meshes. Light fields may be modelled as a 2D array of 2D views, corresponding to a large amount of data, which demands for highly efficient coding solutions. Although s...
The International Standardization Committee ISO/IEC JTC1 SC29 WG1, better known as the Joint Photographic Experts Group (JPEG), has a long tradition in the creation of image coding standards. More than 27 years after the release of the first JPEG standard ISO/IEC 10918, the JPEG format stands as a synonym for digital pictures.
Due to the increasing shortage of fish in the seas, Vessel Monitoring Systems (VMS) play a very important role in fishing activity monitoring, control and surveillance. In this context, the detection of fishing activities in prohibited zones is a critical task. Although position, speed and other information are provided by the VMS system, detecting...
Nowadays, point clouds (PCs) are a promising representation format for immersive content and target several emerging applications, notably in virtual and augmented reality. However, efficient coding solutions are critically needed due to the large amount of PC data required for high quality user experiences. To address these needs, several PC codin...
JPEG Pleno is an upcoming standard from the ISO/IEC JTC 1/SC 29/WG 1 (JPEG) Committee. It aims to provide a standard framework for coding new imaging modalities derived from representations inspired by the plenoptic function. The image modalities addressed by the current standardization activities are light field, holography, and point clouds, wher...
A method for compressing light field data using variable block-size four-dimensional transform and bit-plane hexadeca-tree decomposition, the method including: partitioning a four-dimensional pixel data of a light field into four-dimensional blocks of independent fixed size; partitioning the four-dimensional blocks in a set of four-dimensional non-...
An increased interest in immersive applications has drawn attention to emerging 3D imaging representation formats, notably light fields and point clouds (PCs). Nowadays, PCs are one of the most popular 3D media formats, due to recent developments in PC acquisition, namely with new depth sensors and signal processing algorithms. To obtain high fidel...
Humans mainly communicate among them and with the world around them using light and vision, thus implying that visual representation technologies play a central role in human societies. While visual representation has been based on the 2D representation paradigm for many decades, multiple developments are nowadays pressing towards the adoption of m...
Reliable quality assessment of decoded point cloud geometry is essential to evaluate the compression performance of emerging point cloud coding solutions and guarantee some target quality of experience. This paper proposes a novel point cloud geometry quality assessment metric based on a generalization of the Hausdorff distance. To achieve this goa...
In recent years, visual sensors have been quickly improving, notably targeting richer acquisitions of the light present in a visual scene. In this context, the so-called lenslet light field (LLF) cameras are able to go beyond the conventional 2D visual acquisition models, by enriching the visual representation with directional light measures for ea...
In recent years, visual sensors have been quickly improving, notably targeting richer acquisitions of the light present in a visual scene. In this context, the so-called
lenslet light field (LLF) cameras
are able to go beyond the conventional 2D visual acquisition models, by enriching the visual representation with directional light measures for...
To offer more powerful video-enabled applications, it is increasingly more critical not only to visualize the decoded video but also to provide efficient searching capabilities for similar content. Video surveillance and personal communication are critical application examples asking for these dual visualization and searching functionalities. Howev...
Recently, point clouds have shown to be a promising way to represent 3D visual data for a wide range of immersive applications, from augmented reality to autonomous cars. Emerging imaging sensors have made easier to perform richer and denser point cloud acquisition, notably with millions of points, thus raising the need for efficient point cloud co...
In a world where security issues have been gaining growing importance, face recognition systems have attracted increasing attention in multiple application areas, ranging from forensics and surveillance to commerce and entertainment. To help to understand the landscape and abstraction levels relevant for face recognition systems, face recognition t...
Light field imaging is emerging as an prominent technology in the image and video processing area with a wide range of applications , from the media to the industry and medical fields. However, the huge amount of data generated by the cameras in this type of technology can render its use impractical. This work presents an attempt to use some of the...
Face recognition has attracted increasing attention due to its wide range of applications, but it is still challenging when facing large variations in the biometric data characteristics. Lenslet light field cameras have recently come into prominence to capture rich spatio-angular information, thus offering new possibilities for advanced biometric r...
With the emergence of lenslet light field cameras able to capture rich spatio-angular information from multiple directions, new frontiers in visual recognition performance have been opened. Since multiple 2D viewpoint images can be rendered from a light field, those multiple images, or descriptions extracted from them, can be organized as a pseudo-...
Guaranteeing interoperability between devices and applications is the core role of standards organizations. Since its first JPEG standard in 1992, the Joint Photographic Experts Group (JPEG) has published several image coding standards that have been successful in a plethora of imaging markets. Recently, these markets have become subject to potenti...
In a world where security issues have been gaining growing importance, face recognition systems have attracted increasing attention in multiple application areas, ranging from forensics and surveillance to commerce and entertainment. To help understanding the landscape and abstraction levels relevant for face recognition systems, face recognition t...
Recently, 3D visual representation models such as light fields and point clouds are becoming popular due to their capability to represent the real world in a more complete and immersive way, paving the road for new and more advanced visual experiences. The point cloud representation model is able to efficiently represent the surface of objects/scen...
Face recognition has attracted increasing attention due to its wide range of applications but it is still challenging when facing large variations in the biometric data characteristics. Lenslet light field cameras have recently come into prominence to capture rich spatio-angular information, thus offering new possibilities for designing advanced bi...
Vulnerability of face recognition systems to presentation attacks has attracted increasing attention from the biometrics and forensics communities. Moreover, the recent availability of light field cameras is opening new possibilities for designing improved face presentation attack detection solutions. In this context, this paper provides the first...
Ear recognition is an emerging research area in image-based biometrics. The commercial availability of lenslet light field cameras able to capture full spatio-angular information has brought momentum to biometric and forensic research exploiting this new type of imaging sensors. This study is the first to consider the usage of light field cameras f...
Light and vision are two sides of a coin playing a major role in everyday human life. Over the years, visual related technologies, notably acquisition, representation, coding, transmission, storage, and display have evolved to offer an increasingly large set of functionalities, applications, and services. With the invasion of the digital paradigm,...
Face recognition systems are becoming ubiquitous, but they are vulnerable to spoofing attacks. The recently available light field cameras can be used for spoofing attack detection. In this study, the IST Lenslet Light Field Face Spoofing Database (IST LLFFSD) is proposed, consisting of 100 genuine images, from 50 subjects, captured with a Lytro ILL...
Holography is an emerging technology to represent and display visual information with high expectations in terms of user experience. A hologram is a reproduction of a light field represented through the interference pattern between two wavefields, the reference and the object wavefields. Whatever their creation process, holograms may have a digital...
Popular local feature extraction schemes, such as SIFT, are robust when changes in illumination, translation and scale occur, and play an important role in visual content retrieval. However, these solutions are not very robust to 3D object rotations and camera viewpoint changes. In such scenarios, the emerging and richer lenslet light field image r...
Light field cameras are emerging as powerful devices to capture rich scene representations that provide unique advantages for analysis and representation purposes. Some recent works have shown the power and usefulness of the richer information carried out by light field imaging, notably for face recognition. However, it is still difficult to fully...
JPEG is starting with a new work item called JPEG Pleno. Plenoptic imaging is providing not only information about a pixel in a planar image, but even more how the light representation within a scene changes with the observation point.
In a typical video rate allocation problem, the objective is to optimally distribute a source rate budget among a set of (in)dependently coded data units to minimize the total distortion of all units. Conventional Lagrangian approaches convert the lone rate constraint to a linear rate penalty scaled by a multiplier in the objective, resulting in a...
In a typical video rate allocation problem, the objective is to optimally distribute a source rate budget among a set of (in)dependently coded data units to minimize the total distortion of all units. Conventional Lagrangian approaches convert the lone rate constraint to a linear rate penalty scaled by a multiplier in the objective, resulting in a...
The emerging Scalable HEVC (SHVC) video coding standard provides an efficient solution for transmission of video over heterogeneous and time dynamic networks, terminals, and usage environments. The encoding complexity and the error sensitivity associated to the efficient HEVC coding tools adopted in SHVC make this scalable codec less attractive to...
This paper reports results of subjective and objective quality assessments of responses to a grand challenge on light field image compression. The goal of the challenge was to collect and evaluate new compression algorithms for light field images. In total seven proposals were received, out of which five were accepted for further evaluations. For o...
We consider an interactive multiview video streaming (IMVS) system where
clients select their preferred viewpoint in a given navigation window. To
provide high quality IMVS, many high quality views should be transmitted to the
clients. However, this is not always possible due to the limited and
heterogeneous capabilities of the clients. In this pap...