Light field (LF) videos contain rich spatial, angular, and temporal information, resulting in immense data volumes and posing significant challenges for low-bitrate compression. Existing LF video compression methods focus on modifying the structure of traditional video codecs to encode all LF views, but they are insufficient to achieve low-bitrate compression of LF video. To address these limitations, we propose a low-bitrate LF video compression framework that exploits spatial-angular-temporal correlations through sparse coding and joint reconstruction. On the encoding side, we introduce a content-adaptive prediction structure for sparse key view sequences selection. This structure is adapted to LF video content, leveraging the most similar view as a reference to enhance prediction accuracy and significantly reduce bitrate. On the decoding side, we observe that pixels missing in the current view are often captured in adjacent angular and/or temporal views. As a result, we develop a spatial-angular-temporal based joint reconstruction network that integrates cues across the different domains. This approach supplements missing texture details near occlusion areas and reconstructs high-quality non-key views. Experimental results demonstrate the efficiency of our framework, achieving an average gain of about 60 % in terms of bitrate savings and 2 dB in terms of reconstruction quality compared to the state-of-the-art methods.

The detection results of many existing co-saliency detection methods are easily interfered by the unrelated salient objects, which have similar appearance characteristics to co-salient objects. Therefore, mining the inter-saliency cues which contain the common category information of multiple related images is the core of co-saliency detection. To address above concern, a novel group weakly supervised learning induced co-saliency detection (GWSCoSal) model is proposed in this paper. First of all, a novel group class activation maps (GCAM) network is constructed and trained through a group weakly supervised learning scheme, which adopts the common category of a group of related images as the ground truth. The GCAM produced by the trained GCAM network are considered as the inter-saliency cues, which can only highlight the regions covered by the objects with common category. Afterwards, the GCAM are integrated into a feature pyramid networks (FPN) based backbone trained by the pixel-level labels to infer the co-saliency maps. The group weakly supervised and the pixel-level learning are jointly implemented for end-to-end training of GWSCoSal model. The comprehensive comparisons with 13 state-of-the-art methods demonstrate that, our GWSCoSal model can detect the co-salient objects more accurately under the condition of being interfered by the similar unrelated salient objects, and the overall performance of which has achieved the level of state-of-the-art methods. The ablation study of our GWSCoSal model validates the effectiveness of proposed GCAM network.

MOTIVATION: Identifying protein subchloroplast localization in chloroplast organelle is very helpful for understanding the function of chloroplast proteins. There have existed a few computational prediction methods for protein subchloroplast localization. However, these existing works have ignored proteins with multiple subchloroplast locations when constructing prediction models, so that they can predict only one of all subchloroplast locations of this kind of multilabel proteins. RESULTS: To address this problem, through utilizing label-specific features and label correlations simultaneously, a novel multilabel classifier was developed for predicting protein subchloroplast location(s) with both single and multiple location sites. As an initial study, the overall accuracy of our proposed algorithm reaches 55.52%, which is quite high to be able to become a promising tool for further studies. AVAILABILITY AND IMPLEMENTATION: An online web server for our proposed algorithm named MultiP-SChlo was developed, which are freely accessible at http://biomed.zzuli.edu.cn/bioinfo/multip-schlo/. CONTACT: [email protected] or [email protected] SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Chloroplasts are organelles in most green plant and some algal cells. Identifying protein subchloroplast localization in chloroplast organelle is very helpful for understanding the function of chloroplast proteins. There have existed a few computational prediction methods for protein subchloroplast localization. However, these existing works have ignored proteins with multiple subchloroplast locations when constructing prediction models, so that they can only predict one of all subchloroplast locations of this kind of multilabel proteins. To address this problem, through utilizing label-specific features and label correlations simultaneously, a novel multi-label classifier was developed for predicting protein subchloroplast location(s) with both single and multiple location sites. As an initial study, the overall accuracy of our proposed algorithm reach 55.52%, which is quite high to be able to become a promising tool for further studies.

Inaccuracy depth estimation may influence on depth coding and virtual view rendering in the free-viewpoint television (FTV) system, an improved depth map estimation is proposed to solve the problem for coding and view synthesis. Firstly, check the consistency of initial depth, and the influence of initial miss-matches is minimized by introduction of an additional adaptive matching error selection that penalizes the unreliable matches. Then according to certain criteria, the multi-reference depth maps are merged into one disparity map to improve the quality of disparity map. Finally, a multilateral filtering is used to preserve details in the depth map and simultaneously smooth the depths in occluded areas at object boundary, less texture and discontinuity regions. Experimental results show a significant improvement of the initial input depth maps and coding efficiency, as well as a reduction of view synthesis artifacts.

A depth map represents three-dimensional (3D) scene information and is used to synthesize virtual views in 3D video. Since the quality of synthesized virtual views highly depends on the quality of depth map, efficient depth compression is crucial to realize the 3D video system. However compressing depth map using existing video coding techniques yields unacceptable distortions while rendering virtual views. To solve this problem, we propose an efficient depth map compression method for the view rendering, a novel distortion metric base on view rendering distortions instead of distortion of depth map itself. First, we derive relationships between distortions in coded depth map and rendered view. Then, a region based video characteristics distortion model is proposed for precisely estimation distortion in view synthesis. Finally, experimental results have shown that 1.8 dB coding gain in terms of PSNR and subjective quality improvement of synthesized views are achieved by the proposed method.

Since MODIS data have the feature of huge capacity and multi-spectrum, it needs too much time and frequent I/O operations to correct them by RS software. This paper proposes a parallel algorithm for MODIS Data based on triangulation network. The input images are divided into several pieces and each CPU processes a piece independently. By implementing the algorithm on a cluster system, the results show that, this parallel algorithm improves the efficiency of geometrical correction greatly.