Ioannis Katsavounidis
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View article: FaceExpressions-70k: A Dataset of Perceived Expression Differences
FaceExpressions-70k: A Dataset of Perceived Expression Differences Open
View article: AIM 2024 Challenge on Efficient Video Super-Resolution for AV1 Compressed Content
AIM 2024 Challenge on Efficient Video Super-Resolution for AV1 Compressed Content Open
Video super-resolution (VSR) is a critical task for enhancing low-bitrate and low-resolution videos, particularly in streaming applications. While numerous solutions have been developed, they often suffer from high computational demands, r…
View article: Subjective and Objective Quality Assessment of Rendered Human Avatar Videos in Virtual Reality
Subjective and Objective Quality Assessment of Rendered Human Avatar Videos in Virtual Reality Open
We study the visual quality judgments of human subjects on digital human avatars (sometimes referred to as "holograms" in the parlance of virtual reality [VR] and augmented reality [AR] systems) that have been subjected to distortions. We …
View article: SVT-AV1 Encoding Bitrate Estimation Using Motion Search Information
SVT-AV1 Encoding Bitrate Estimation Using Motion Search Information Open
Enabling high compression efficiency while keeping encoding energy consumption at a low level, requires prioritization of which videos need more sophisticated encoding techniques. However, the effects vary highly based on the content, and …
View article: Real-Time 4K Super-Resolution of Compressed AVIF Images. AIS 2024 Challenge Survey
Real-Time 4K Super-Resolution of Compressed AVIF Images. AIS 2024 Challenge Survey Open
This paper introduces a novel benchmark as part of the AIS 2024 Real-Time Image Super-Resolution (RTSR) Challenge, which aims to upscale compressed images from 540p to 4K resolution (4x factor) in real-time on commercial GPUs. For this, we…
View article: Joint Quality Assessment and Example-Guided Image Processing by Disentangling Picture Appearance from Content
Joint Quality Assessment and Example-Guided Image Processing by Disentangling Picture Appearance from Content Open
The deep learning revolution has strongly impacted low-level image processing tasks such as style/domain transfer, enhancement/restoration, and visual quality assessments. Despite often being treated separately, the aforementioned tasks sh…
View article: Cut-FUNQUE: An Objective Quality Model for Compressed Tone-Mapped High Dynamic Range Videos
Cut-FUNQUE: An Objective Quality Model for Compressed Tone-Mapped High Dynamic Range Videos Open
High Dynamic Range (HDR) videos have enjoyed a surge in popularity in recent years due to their ability to represent a wider range of contrast and color than Standard Dynamic Range (SDR) videos. Although HDR video capture has seen increasi…
View article: Encoding Time and Energy Model for SVT-AV1 based on Video Complexity
Encoding Time and Energy Model for SVT-AV1 based on Video Complexity Open
The share of online video traffic in global carbon dioxide emissions is growing steadily. To comply with the demand for video media, dedicated compression techniques are continuously optimized, but at the expense of increasingly higher com…
View article: Estimating Metric Thresholds For Acceptability and Annoyance of User Generated Video Content
Estimating Metric Thresholds For Acceptability and Annoyance of User Generated Video Content Open
User expectation is one of the main factors that drives the user satisfaction for video streaming service providers and online social media platforms. Depending on the context, users may have different expectations of the video quality. Me…
View article: A FUNQUE Approach to the Quality Assessment of Compressed HDR Videos
A FUNQUE Approach to the Quality Assessment of Compressed HDR Videos Open
Recent years have seen steady growth in the popularity and availability of High Dynamic Range (HDR) content, particularly videos, streamed over the internet. As a result, assessing the subjective quality of HDR videos, which are generally …
View article: Bitrate Ladder Construction using Visual Information Fidelity
Bitrate Ladder Construction using Visual Information Fidelity Open
Recently proposed perceptually optimized per-title video encoding methods provide better BD-rate savings than fixed bitrate-ladder approaches that have been employed in the past. However, a disadvantage of per-title encoding is that it req…
View article: Table of Contents
Table of Contents Open
View article: Encoder Complexity Control in SVT-AV1 by Speed-Adaptive Preset Switching
Encoder Complexity Control in SVT-AV1 by Speed-Adaptive Preset Switching Open
Current developments in video encoding technology lead to continuously improving compression performance but at the expense of increasingly higher computational demands. Regarding the online video traffic increases during the last years an…
View article: Video Consumption in Context: Influence of Data Plan Consumption on QoE
Video Consumption in Context: Influence of Data Plan Consumption on QoE Open
International audience
View article: Study of Subjective and Objective Quality Assessment of Mobile Cloud Gaming Videos
Study of Subjective and Objective Quality Assessment of Mobile Cloud Gaming Videos Open
We present the outcomes of a recent large-scale subjective study of Mobile Cloud Gaming Video Quality Assessment (MCG-VQA) on a diverse set of gaming videos. Rapid advancements in cloud services, faster video encoding technologies, and inc…
View article: One Transform To Compute Them All: Efficient Fusion-Based Full-Reference Video Quality Assessment
One Transform To Compute Them All: Efficient Fusion-Based Full-Reference Video Quality Assessment Open
The Visual Multimethod Assessment Fusion (VMAF) algorithm has recently emerged as a state-of-the-art approach to video quality prediction, that now pervades the streaming and social media industry. However, since VMAF requires the evaluati…
View article: Lightweight Image Codec via Multi-Grid Multi-Block-Size Vector Quantization (MGBVQ)
Lightweight Image Codec via Multi-Grid Multi-Block-Size Vector Quantization (MGBVQ) Open
A multi-grid multi-block-size vector quantization (MGBVQ) method is proposed for image coding in this work. The fundamental idea of image coding is to remove correlations among pixels before quantization and entropy coding, e.g., the discr…
View article: Ptr-Cnn for In-Loop Filtering in Video Coding
Ptr-Cnn for In-Loop Filtering in Video Coding Open
View article: Towards much better SVT-AV1 quality-cycles tradeoffs for VOD applications
Towards much better SVT-AV1 quality-cycles tradeoffs for VOD applications Open
Software video encoders that have been developed based on the AVC, HEVC, VP9, and AV1 video coding standards have provided improved compression efficiency but at the cost of large increases in encoding complexity. As a result, there is cur…
View article: A Machine Learning Approach to Optimal Inverse Discrete Cosine Transform (IDCT) Design
A Machine Learning Approach to Optimal Inverse Discrete Cosine Transform (IDCT) Design Open
The design of the optimal inverse discrete cosine transform (IDCT) to compensate the quantization error is proposed for effective lossy image compression in this work. The forward and inverse DCTs are designed in pair in current image/vide…
View article: A Hitchhiker’s Guide to Structural Similarity
A Hitchhiker’s Guide to Structural Similarity Open
The Structural Similarity (SSIM) Index is a very widely used image/video\nquality model that continues to play an important role in the perceptual\nevaluation of compression algorithms, encoding recipes and numerous other\nimage/video proc…
View article: A Simple Model for Subject Behavior in Subjective Experiments
A Simple Model for Subject Behavior in Subjective Experiments Open
In a subjective experiment to evaluate the perceptual audiovisual quality of multimedia and television services, raw opinion scores collected from test subjects are often noisy and unreliable. To produce the final mean opinion scores (MOS)…
View article: A Simple Model for Subject Behavior in Subjective Experiments
A Simple Model for Subject Behavior in Subjective Experiments Open
In a subjective experiment to evaluate the perceptual audiovisual quality of multimedia and television services, raw opinion scores offered by subjects are often noisy and unreliable. Recommendations such as ITU-R BT.500, ITU-T P.910 and I…
View article: Towards Perceptually Optimized End-to-end Adaptive Video Streaming
Towards Perceptually Optimized End-to-end Adaptive Video Streaming Open
Measuring Quality of Experience (QoE) and integrating these measurements into video streaming algorithms is a multi-faceted problem that fundamentally requires the design of comprehensive subjective QoE databases and metrics. To achieve th…
View article: A user model for JND-based video quality assessment: theory and applications
A user model for JND-based video quality assessment: theory and applications Open
The video quality assessment (VQA) technology has attracted a lot of attention in recent years due to an increasing demand of video streaming services. Existing VQA methods are designed to predict video quality in terms of the mean opinion…
View article: Prediction of Satisfied User Ratio for Compressed Video
Prediction of Satisfied User Ratio for Compressed Video Open
A large-scale video quality dataset called the VideoSet has been constructed recently to measure human subjective experience of H.264 coded video in terms of the just-noticeable-difference (JND). It measures the first three JND points of 5…
View article: VideoSet: A large-scale compressed video quality dataset based on JND measurement
VideoSet: A large-scale compressed video quality dataset based on JND measurement Open
• A large-scale JND-based coded video quality dataset is presented. • The VideoSet contains 220 5-s sequences in four resolutions coded by H.264/AVC. • The subjective test procedure, JND data cleaning and properties are described. • The si…
View article: VideoSet: A Large-Scale Compressed Video Quality Dataset Based on JND Measurement
VideoSet: A Large-Scale Compressed Video Quality Dataset Based on JND Measurement Open
A new methodology to measure coded image/video quality using the just-noticeable-difference (JND) idea was proposed. Several small JND-based image/video quality datasets were released by the Media Communications Lab at the University of So…