JOIG leads with cutting-edge research in image, video, and graphics technology - your gateway to innovations enhancing daily life and shaping a smart future. Peer-reviewed articles, published quarterly, illuminate the path to tomorrow's solutions.

Digital audio–tactile maps (DATMs) on touchscreen devices provide valuable opportunities for people who are visually impaired (PVIs) to explore the spatial environment for engaging in travel activities. Existing solutions for DATMs usually require extensive training for the PVIs to understand the feedback mechanism. Due to the shortage of human resources for training specialists, as well as PVIs’ desire for frequent practice to maintain their usage skills, it has become challenging to widely adopt DATMs in real life. This paper discusses the use of large language models (LLMs) to provide a verbal evaluation of the PVIs’ perception, which is crucial for the independent practice of DATM usage. A smartphone-based prototype providing DATMs of simple floor plans was developed for a preliminary investigation. The evaluation results have proven that the interaction with the LLM could help the participants better understand the DATMs’ content and could vividly replicate them by drawings.

In mobile short-form video streaming, the video application usually provides the user with a playlist of recommended videos to be played one by one. In order to prevent playback stalls caused by possible fluctuations in the mobile network, after finishing buffering the currently-playing video, commercial video players continue to prebuffer (i.e., buffer in advance before playback) one subsequent video in the playlist with as much content as possible. However, since the user can skip a video at any time if he/she does not like it, prebuffering too much video content leads to the wastage of mobile data. Contrarily, without prebuffering any subsequent video, the video player is exposed to high risks of stalling events, which threaten the user’s quality of experience (QoE). In this paper, a novel Sprinkle Prebuffer Strategy (SPS) is proposed to overcome such drawbacks. Once the currently-playing video’s buffer reaches an optimal buffer threshold, the proposed SPS attempts to concurrently prebuffer all subsequent videos in the playlist, each up to an optimal prebuffer threshold. Based on the evaluation results, it is proven that the proposed SPS outperforms the referenced methods in providing the best user’s QoE with reasonable compensation for data wastage.

This paper presents a novel approach to mind-wandering prediction in the context of webcam-based online learning. We implemented a Singular Value Decomposition (SVD)-based 1D temporal eye-signal extraction method, which relies solely on eye landmark detection and eliminates the need for gaze tracking or specialized hardware, then extract suitable features from the signals to train the prediction model. Our thorough experimental framework facilitates the evaluation of our approach alongside baseline models, particularly in the analysis of temporal eye signals and the prediction of attentional states. Notably, our SVD-based signal captures both subtle and major eye movements, including changes in the eye boundary and pupil, surpassing the limited capabilities of eye aspect ratio (EAR)-based signals. Our proposed model exhibits a 2% improvement in the overall Area Under the Receiver Operating Characteristics curve (AUROC) metric and 7% in the F1-score metric for ‘not-focus’ prediction, compared to the combination of EAR-based and computationally intensive gaze-based models used in the baseline study These contributions have potential implications for enhancing the field of attentional state prediction in online learning, offering a practical and effective solution to benefit educational experiences.

In light field compression, graph-based coding is powerful to exploit signal redundancy along irregular shapes and obtains good energy compaction. However, apart from high time complexity to process high dimensional graphs, their graph construction method is highly sensitive to the accuracy of disparity information between viewpoints. In real-world light field or synthetic light field generated by computer software, the use of disparity information for super-rays projection might suffer from inaccuracy due to vignetting effect and large disparity between views in the two types of light fields, respectively. This paper introduces two novel projection schemes resulting in less error in disparity information, in which one projection scheme can also significantly reduce computation time for both encoder and decoder. Experimental results show projection quality of super-pixels across views can be considerably enhanced using the proposals, along with rate-distortion performance when compared against original projection scheme and HEVC-based or JPEG Pleno-based coding approaches.