Christos Grecos

Christos Grecos
Central Washington University | CWU

About

199
Publications
16,618
Reads
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1,247
Citations
Introduction
Christos Grecos currently works at Central Washington University. Christos does research in Distributed Computing, Computer Graphics and Computer Communications (Networks). Their current project is 'video compression, analysis and transmission'.

Publications

Publications (199)
Article
This research addresses an interdisciplinary problem area concerning the long-term deployment of socially embedded technology in authentic environments. It concentrates on the case of ambient displays, where long-term research in the real world is still scant and evidentially requires methodological development. This study seeks to advance on this...
Chapter
Histogram-based watermarking schemes are invariant to pixel permutations and can thus be combined with permutation-based ciphers to form a commutative watermarking-encryption scheme. In this chapter, the authors demonstrate the feasibility of this approach for audio data and still image data. Typical histogram-based watermarking schemes based on co...
Article
Tai, X.; Wang, G.; Grecos, C., and Ren, P., 2020. Coastal image classification under noisy labels. In: Jung, H.-S.; Lee, S.; Ryu, J.-H., and Cui, T. (eds.), Advances in Geospatial Research of Coastal Environments. Journal of Coastal Research, Special Issue No. 102, pp. 151-156. Coconut Creek (Florida), ISSN 0749-0208. Remote sensing coastal images...
Article
Full-text available
High-Efficiency Video Coding (HEVC) is the new emerging video coding standard of the ITU-T Video Coding Experts Group (VCEG) and the ISO/IEC Moving Picture Experts Group (MPEG). The HEVC standard provides a significant improvement in compression efficiency in comparison with existing standards such as H264/AVC by means of greater complexity. In thi...
Conference Paper
Complex event processing (CEP) systems are typically utilised for smart environments to cope with large numbers of components and events without simultaneously increasing latencies for user interaction. Although CEP systems can simplify the development of components with CEP queries, it remains challenging to debug such complex distributed systems....
Article
Fast and accurate remote sensing image retrieval from large data archives has been an important research topic in the remote sensing research literature. Recently, hashing-based remote sensing image retrieval has attracted extreme attention because of its efficient search capabilities. Especially, deep remote sensing image hashing algorithms have b...
Article
Full-text available
Recently, the demand for remote sensing image retrieval is growing and attracting the interest of many researchers because of the increasing number of remote sensing images. Hashing, as a method of retrieving images, has been widely applied to remote sensing image retrieval. In order to improve hashing performance, we develop a cohesion intensive d...
Article
We develop a hierarchical generative adversarial network (HGAN) for generating future typhoon cloud remote sensing images, which enables a visual means to typhoon cloud prediction. The HGAN consists of a global generator and a local discriminator. The global generator aims at producing the future typhoon cloud images as realistic as possible and ac...
Article
Existing artificial intelligence solutions typically operate in powerful platforms with high computational resources availability. However, a growing number of emerging use cases such as those based on unmanned aerial systems (UAS) require new solutions with embedded artificial intelligence on a highly mobile platform. This paper proposes an innova...
Article
We exploit the alternating direction method of multipliers (ADMM) for developing an oil spill segmentation method, which effectively detects oil spill regions in blurry synthetic aperture radar (SAR) images. We commence by constructing energy functionals for SAR image deblurring and oil spill segmentation separately. We then integrate the two energ...
Conference Paper
Object detection systems mounted on Unmanned Aerial Vehicles (UAVs) have gained momentum in recent years in light of the widespread use cases enabled by such systems in public safety and other areas. Machine learning has emerged as an enabler for improving the performance of object detection. However, there is little existing work that has studied...
Article
Dynamic Adaptive Streaming over HTTP (DASH) is a popular over-the-top video content distribution technique that adapts the streaming session according to the user's network condition typically in terms of downlink bandwidth. This video quality adaptation can be achieved by scaling the frame quality, spatial resolution or frame rate. Despite the fle...
Article
Before being applied in oil fields, it’s necessary to evaluate the quality of fracturing proppants, for which sphericity and roundness are two important parameters. In this paper, we propose a new approach to the sphericity and roundness measurement of proppants based on an image processing method. Firstly, the OTSU method is introduced to binarize...
Chapter
Histogram-based watermarking schemes are invariant to pixel permutations and can thus be combined with permutation-based ciphers to form a commutative watermarking-encryption scheme. In this chapter, the authors demonstrate the feasibility of this approach for audio data and still image data. Typical histogram-based watermarking schemes based on co...
Chapter
Mobile video applications have started to dominate the global mobile data traffic in recent years, and both opportunities and challenges have arisen when the emerging mobile cloud paradigm is introduced to support the resource-demanding video processing and networking services. This chapter offers in-depth discussions for content- and context-aware...
Conference Paper
Full-text available
Affective application developers often face a challenge in integrating the output of facial expression recognition (FER) software in interactive systems: although many algorithms have been proposed for FER, integrating the results of these algorithms into applications remains difficult. Due to inter-and within-subject variations further post-proces...
Article
We exploit the alternating direction method of multipliers (ADMM) for developing an oil spill segmentation method, which effectively detects oil spill regions in blurry synthetic aperture radar (SAR) images. We commence by constructing energy functionals for SAR image deblurring and oil spill segmentation separately. We then integrate the two energ...
Chapter
Digital healthcare is becoming increasingly important as the ageing population and the number of people diagnosed with chronic diseases is increasing. The face of healthcare delivery has changed radically and at its core is a digital and customer revolution. Connected health is the convergence of medical devices, security devices, and communication...
Conference Paper
Full-text available
In this paper, we provide insights towards achieving more robust automatic facial expression recognition in smart environments based on our benchmark with three labeled facial expression databases. These databases are selected to test for desktop, 3D and smart environment application scenarios. This work is meant to provide a neutral comparison and...
Chapter
Digital healthcare is becoming increasingly important as the ageing population and the number of people diagnosed with chronic diseases is increasing. The face of healthcare delivery has changed radically and at its core is a digital and customer revolution. Connected health is the convergence of medical devices, security devices, and communication...
Conference Paper
Full-text available
In this work we enhance our previously developed analysis method of provoked emotions in facial expressions through the analysis of physiological data. The presented work describes the integration of electrodermal activity, respiration and temperature sensors to enhance our exergaming system for emotional provocation. The combined analysis of facia...
Conference Paper
This paper contributes long-term findings on a custom ambient display solution (Ambient Surfaces) in the informative workspace of co-located agile (Scrum) software development teams. The study is based on the premise that displaying relevant information in a team's informative workspace is beneficial, as it readily provides information of common in...
Conference Paper
Scaling the number of supported users for Massive Multi-User Games (MMOGs) allows more users to experience its content together. Supporting this capability needs consider the chain of all components that constitute the system between the client software of any two users. A large body of research has been created over the last decades on the problem...
Article
The upsurge of mobile devices paired with highly interactive social web applications generates enormous amounts of requests web services have to deal with. Consequently in our previous work, a novel request flow scheme with scalable components was proposed for storing interdependent, permanently updated resources in a database. The major challenge...
Conference Paper
This paper proposes a new approach to improving the application of 3D video rendering and streaming by jointly exploring and optimizing both cloud-based virtualization and web-based delivery. The proposed web service architecture firstly establishes a software virtualization layer based on QEMU (Quick Emulator), an open-source virtualization softwa...
Conference Paper
Adaptive video streaming using HTTP has become popular in recent years for commercial video delivery. The recent MPEG-DASH standard allows interoperability and adaptability between servers and clients from different vendors. The delivery of the MPD (Media Presentation Description) files in DASH and the DASH client behaviours are beyond the scope of...
Conference Paper
As the capabilities of high end consumer devices increase, streaming and playback of ultra-high definition (UHD) is set to become commonplace. Already UHD televisions, display screens and even mobile devices with 4K (3840 x 2160) screen resolutions are widely available and full ultra-high definition (FUHD) 8K (7680 x 4320) televisions are beginning...
Conference Paper
Software Defined Networks (SDN), when combined with Network Function Virtualization (NFV) represents a paradigm shift in how future networks will behave and be managed. SDN’s are expected to provide the underpinning technologies for future innovations such as 5G mobile networks and the Internet of Everything. The SDN architecture offers features th...
Article
The high efficiency video coding standard provides excellent coding performance but is also very complex. Especially, the intra mode decision is very time-consuming due to the large number of available prediction modes and the flexible block partitioning scheme. In this paper, a highly parallel intra prediction algorithm for heterogeneous CPU+graph...
Conference Paper
The High Efficiency Video Coding (HEVC) standard provides an outstanding compression performance and is thus ideally suited for Ultra High Definition (UHD) content. However, the complexity of the encoder is substantial and therefore highly optimized implementations are required to achieve reasonable speeds. For this purpose, high-level parallelizat...
Article
We present a novel marine oil spill segmentation method that characterizes two smoothing modules at the label level and the pixel level separately. At the label level, we exploit the rolling guidance filter for smoothing the label cost volumes. It enables scale-aware labeling and thus alleviates the ambiguous segmentation that blurs the detailed st...
Chapter
Mobile video applications have started to dominate the global mobile data traffic in recent years, and both opportunities and challenges have arisen when the emerging mobile cloud paradigm is introduced to support the resource-demanding video processing and networking services. This chapter offers in-depth discussions for content- and context-aware...
Conference Paper
Full-text available
Content-fragile commutative watermarking-encryption requires that both the content-fragile image signature and the watermarking process are invariant under encryption. The pixel entropy, being dependent on first-order image statistics only, is invariant under permutations. In the present paper we embed semi-fragile signatures based on pixel entropy...
Conference Paper
Full-text available
In this work, we investigate the effect of how exercise game design elements generate deliberate real-time sensed emotional responses in gamers. Our experimental setup consists of a cycling game controller, a designed 3D first-person cycling game to provoke emotions, a data recording system, and an emotion analysis system. The physical cycling game...
Article
Connected health is the convergence of medical devices, security devices, and communication technologies. It enables patients to be monitored and treated remotely from their home or primary care facility rather than attend outpatient clinics or be admitted to hospital. Patients' data and medical records within a connected health system should be se...
Article
Nowadays, web services have to accommodate a significant and ever-increasing number of requests due to high interactivity of current applications. Although the built-in elasticity offered by a cloud can mitigate this challenge, it is highly desirable that applications can be built in a scalable fashion. State-of-the-art Web Application Frameworks (...
Article
The application of small civilian unmanned aerial vehicles (UAVs) has attracted great interest for disaster sensing. However, the limited computational capability and low energy resource of UAVs present a significant challenge to real-time data processing, networking and policy making, which are of vital importance to many disaster related applicat...
Conference Paper
The Motion Imagery Standards Board (MISB) specifies imaging standards in the military domain. MISB standards are based on commercial standards which, although proven, are at least 10 years old and do not represent the current state of the art in video encoding. High Efficiency Video Coding (HEVC), a major step forward in video compression technolog...
Conference Paper
Distributed Virtual Environments (DVEs) can handle large numbers of participants by optimizing the routing of state update messages sent to the computer of the individual participant. Often Area of Interest (AoI) management is used to limit the information an avatar can observe and thus the necessary state update messages that are sent to the clien...
Article
Full-text available
IntroductionMultimedia networking applications benefit from the rapid development of encoding/compression techniques multimedia data sources, effective Quality of Service (QoS) management mechanisms and Quality of Experience (QoE) criteria for system optimization. This special issue aims to expose the readership to the latest research results on mu...
Conference Paper
The latest trend to access mobile cloud services through wireless network connectivity has amplified globally among both entrepreneurs and home end users. Although existing public cloud service vendors such as Google, Microsoft Azure etc. are providing on-demand cloud services with affordable cost for mobile users, there are still a number of chall...
Article
The recent explosion in video-related Internet traffic has been driven by the widespread use of smart mobile devices, particularly smartphones with advanced cameras that are able to record high-quality videos. Although many of these devices offer the facility to record videos at different spatial and temporal resolutions, primarily with local stora...
Conference Paper
In recent years video traffic has become the dominant application on the Internet with global year-on-year increases in video-oriented consumer services. Driven by improved bandwidth in both mobile and fixed networks, steadily reducing hardware costs and the development of new technologies, many existing and new classes of commercial and industrial...
Conference Paper
Video streaming and other multimedia applications account for an ever increasing proportion of all network traffic. The recent adoption of High Efficiency Video Coding (HEVC) as the H.265 standard provides many opportunities for new and improved services multimedia services and applications in the consumer domain. Since the delivery of version one...
Chapter
Mobile video applications have started to dominate the global mobile data traffic in recent years, and both opportunities and challenges have arisen when the emerging mobile cloud paradigm is introduced to support the resource-demanding video processing and networking services. This chapter offers in-depth discussions for content- and context-aware...
Article
Video and multimedia streaming services continue to grow in popularity and are rapidly becoming the largest consumers of network capacity in both fixed and mobile networks. In this article, we discuss the latest advances in video compression technology and demonstrate their potential to improve service quality for consumers whilst reducing bandwidt...
Article
The received signal strength (RSS) of wireless signals has been widely used in communications, localization and tracking. Theoretical modelling and practical applications often make a white noise assumption when dealing with RSS measurements. However, as we will show in this paper, the noise present in RSS measurements has time-dependency propertie...
Article
High Efficiency Video Coding (HEVC), the latest video compression standard, will play an important role in many multimedia applications in the foreseeable future. Its superior compression performance enables HEVC to be particularly suitable for high-definition videos in consumer electronics environments; however, it comes with the price of substant...
Article
Full-text available
Invariant Commutative Watermarking-Encryption means to use a cipher that does not have any impact on a certain feature space, which can thus be used for embedding watermarks either before or after encryption. For example, histogram-based watermarking schemes are invariant to pixel permutations and can be combined with permutation-based ciphers to f...
Article
When multiple mobile robots (e.g., robotic equipment and unmanned aerial vehicles (UAVs)) are deployed to work cooperatively, it is usually difficult to jointly optimize the algorithms involving the following two aspects: finding optimal paths and maintaining reliable network connectivity. This is due to the fact that both these objectives require...
Conference Paper
Full-text available
This paper presents a common stochastic modeling framework for physiological signals which allows patient simulation following a synthesis-by-analysis approach. Within this framework, we propose a general model-based methodology able to reconstruct missing or artifacted signal intervals in cardiovascular monitoring applications. The proposed model...
Article
The high efficiency video coding standard (HEVC) is the next-generation standard developed by the Joint Collaborative Team in Video Coding (JCT-VC). This new standard aims to achieve 50 % bit rate saving with similar objective quality compared to H.264/AVC. A very flexible quadtree coding structure characterized by coding units (CUs), prediction u...
Conference Paper
We present a real-time multi-target tracking system that effectively deals with false positive detections. In order to achieve this, we build a novel motion model that treats false positives on background objects and false positives on foreground objects such as shoulders or bags separately. In addition we train a new head detector based on the Agg...
Conference Paper
The social web and huge growth of mobile smart devices dramatically increases the performance requirements for web services. State-of-the-art Web Application Frameworks (WAFs) do not offer complete scaling concepts with automatic resource-provisioning, elastic caching or guaranteed maximum response times. These functionalities, however, are support...
Conference Paper
Mobile cloud computing is receiving world-wide momentum for ubiquitous on-demand cloud services for mobile users provided by Amazon, Google etc. with low capital cost. However, Internet-centric clouds introduce wide area network (WAN) delays that are often intolerable for real-time applications such as video streaming. One promising approach to add...
Conference Paper
Mobile cloud computing is receiving world-wide momentum for ubiquitous on-demand cloud services for mobile users provided by Amazon, Google etc. with low capital cost. However, Internet-centric clouds introduce wide area network (WAN) delays that are often intolerable for real-time applications such as video streaming. One promising approach to add...
Conference Paper
Real-time HTTP streaming has gained global popularity for delivering video content over Internet. In particular, the recent MPEG-DASH (Dynamic Adaptive Streaming over HTTP) standard enables on-demand, live, and adaptive Internet streaming in response to network bandwidth fluctuations. Meanwhile, emerging is the new-generation video coding standard,...
Conference Paper
This paper describes a comprehensive empirical performance evaluation of 3D video processing employing the physical/virtual architecture implemented in a cloud environment. Different virtualization technologies, virtual video cards and various 3D benchmarks tools have been utilized in order to analyse the optimal performance in the context of 3D on...
Article
— Users of modern portable consumer devices (smartphones, tablets etc.) expect ubiquitous delivery of high quality services, which fully utilise the capabilities of their devices. Video streaming is one of the most widely used yet challenging services for operators to deliver with assured service levels. This challenge is more apparent in wireless...
Conference Paper
In emergency situations, the ability to remotely monitor unfolding events using high-quality video feeds will significantly improve the incident commander’s understanding of the situation and thereby aids effective decision making. This paper presents a novel, adaptive video monitoring system for emergency situations where the normal communications...