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Lossless coding of light field images based on minimum-rate predictors

JOURNAL OF VISUAL COMMUNICATION AND IMAGE REPRESENTATION 2018年第Jul.期54卷 21-30页

作者： Santos, Joao M. Assuncao, Pedro A. A. da Silva Cruz, Luis A. Tavora, Luis M. N. Fonseca-Pinto, Rui Faria, Sergio M. M. Inst Telecomunicacoes IPLeiria Campus 2 P-2411901 Leiria Portugal Univ Coimbra Fac Sci & Technol Dept Elect & Comp Engn P-3030290 Coimbra Portugal Inst Politecn Leiria ESTG P-2411901 Leiria Portugal

Recent developments in light field acquisition and computational photography are driving new research efforts on light field encoding methods, capable of exploiting the specific features of this type of visual data. This paper presents a research study of lossless light field image compression, using Minimum-Rate Predictors (MRP) and mainstream image and video encoders. The research is focused on three light field representation formats: lenslet images, stack of sub-aperture images and epipolar images. The main contributions of this work are the 'Spiral-blackend' serialization method and the use of MRP for the lossless compression of light fields with joint encoding of RGB data. The results show that the lenslet format yields lower compression efficiencies than other formats. Furthermore, it is demonstrated that the MRP algorithm consistently outperforms HEVC-RExt, JPEG2000, JPEG-LS and CALIC when light fields are represented by either a stack of sub-aperture or epipolar images.

关键词： Image coding Lossless compression light field coding

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A low complexity Wyner-Ziv coding solution for light field image transmission and storage

A low complexity Wyner-Ziv coding solution for Light Field i...

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IEEE International Symposium on Broadband Multimedia Systems and Broadcasting (BMSB)

作者： Cong, Huy Phi Perry, Stuart HoangVan, Xiem VNU Univ Engn & Technol Hanoi Vietnam VNU Univ Engn & Technol JTIRC Hanoi Vietnam Univ Technol Sydney Sch Elect & Data Engn Sydney NSW Australia Univ Technol Sydney Sydney NSW Australia

ISBN: (纸本)9781728121505

Compressing light field (LF) imaging data is a challenging but very important task for both LF image transmission and storage applications. In this paper, we propose a novel coding solution for LF images using the well-known Wyner-Ziv (WZ) information theorem. First, the LF image is decomposed into a fourth-dimensional LF (4D-LF) data format. Using a spiral scanning procedure, a pseudo-sequence of 4D-LF is generated. This sequence is then compressed in a distributed coding manner as specified in the WZ theorem. Secondly, a novel adaptive frame skipping algorithm is introduced to further explore the high correlation between 4D-LF pseudo-sequences. Experimental results show that the proposed IF image compression solution is able to achieve a significant performance improvement with respect to the standard, notably around 54% bitrate saving when compared with the standard High Efficiency Video coding (HEVC) Intra benchmark while requiring less computational complexity.

关键词： light field coding distributed video coding Wyner-Ziv coding Signal processing

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HIGH EFFICIENCY coding OF light field IMAGES BASED ON TILING AND PSEUDO-TEMPORAL DATA ARRANGEMENT

HIGH EFFICIENCY CODING OF LIGHT FIELD IMAGES BASED ON TILING...

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IEEE International Conference on Multimedia & Expo (ICME)

作者： Perra, C. Assuncao, P. Univ Cagliari Dept Elect & Elect Engn I-09124 Cagliari Italy IPLeiria Inst Telecomunicacoes Leiria Portugal

ISBN: (纸本)9781509015528

Digital light fields are obtained by sampling of huge number of light rays, capturing the colour intensity of a whole visual scene from different view angles. The large amount of data that is necessary to represent a light field requires highly efficient compression methods to store and exchange such type of signals. This paper presents a light field coding scheme based on a low-complexity preprocessing approach that generates a pseudo-video sequence suitable for standard compression using HEVC. The efficiency of the proposed scheme is evaluated using a data set of twelve light field images and low-delay B HEVC coding configuration. The R-D performance obtained by the proposed scheme is consistently better than JPEG, revealing significantly higher gains, particularly for higher compression ratios.

关键词： light field coding HEVC Tiling Pseudo-video sequence Reordering

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Plenoptic Image coding Using Macropixel-Based Intra Prediction

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IEEE TRANSACTIONS ON IMAGE PROCESSING 2018年第8期27卷 3954-3968页

作者： Jin, Xin Han, Haixu Dai, Qionghai Tsinghua Univ Grad Sch Shenzhen Shenzhen Key Lab Broadband Network & Multimedia Shenzhen 518055 Peoples R China Tsinghua Univ TNLIST Beijing 100084 Peoples R China Tsinghua Univ Dept Automat Beijing 100084 Peoples R China

The plenoptic image in a super high resolution is composed of a number of macropixels recording both spatial and angular light radiance. Based on the analysis of spatial correlations of macropixel structure, this paper proposes a macropixel-based intra prediction method for plenoptic image coding. After applying an invertible image reshaping method to the plenoptic image, the macropixel structures are aligned with the coding unit grids of a block-based video coding standard. The reshaped and regularized image is compressed by the video encoder comprising the proposed macropixel-based intra prediction, which includes three modes: multi-block weighted prediction mode (MWP);co-located single-block prediction mode;and boundary matching-based prediction mode (BMP). In the MWP mode and BMP mode, the predictions are generated by minimizing spatial Euclidean distance and boundary error among the reference samples, respectively, which can fully exploit spatial correlations among the pixels beneath the neighboring microlens. The proposed approach outperforms high-efficiency video coding standard by an average of 47.0% Nitrate reduction. Compared with other state-of-the-art methods, such as pseudo-video based on tiling and arrangement method, intra block copy mode, and locally linear embedding-based prediction, it can also achieve 45.0%, 27.7%, and 22.7% bitrate savings on average, respectively.

关键词： Plenoptic image coding macropixel-based intra prediction light field coding HEVC/H.265

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Image Reshaping for Efficient Compression of Plenoptic Content

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IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING 2017年第7期11卷 1173-1186页

作者： Jin, Xin Han, Haixu Dai, Qionghai Tsinghua Univ Grad Sch Shenzhen Shenzhen Key Lab Broadband Network & Multimedia Shenzhen 518055 Peoples R China Tsinghua Univ Tsinghua Natl Lab Informat Sci & Technol Shenzhen 518055 Peoples R China Tsinghua Univ Dept Automat Shenzhen 518055 Peoples R China

With insertion of an additional microlens array in front of the imaging sensor, plenoptic camera, which acquires light field by a single exposure, attracts great interests both from academy and industry. A plenoptic image records both spatial and angular light radiance in a super high definition with macropixel structures, which results in a distinct intensity distribution. Several compression techniques have been proposed, however, most of them are suffered from the standard incompatibility and high compression complexity. In this paper, a novel and standard compatible plenoptic data reshaping algorithm is proposed to align the macropixel structures in the lenslet image with the coding unit grids of block-based image/video coding standards before compression. After encoding and decoding the reshaped lenslet image using the existing block-based image/video coding standards, the inverse image reshaping is used to convert the reconstructed image back to the original light-field data format for further applications. The experimental results reveal that the proposed method introduces 10.47% and 27.64% bitrate reduction to HEVC/H.265 format range extension profile and AVC/H.264 high 4:4:4 profile, respectively, by compressing the reshaped lenslet images. Also, it brings additional compression efficiency improvements to intraprediction tools, such as intrablock copy and locally linear embedding based coding method, by an average of 11.62% and 9.81% bitrate reduction as they compress the reshaped plenoptic images.

关键词： AVC/H.264 HEVC/H.265 light field coding plenoptic image compression video coding

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A Hierarchical Approach for Lossy light field Compression With Multiple Bit Rates Based on Tucker Decomposition via Random Sketching

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IEEE ACCESS 2022年 10卷 56677-56690页

作者： Ravishankar, Joshitha Sharma, Mansi Indian Inst Technol Madras Dept Elect Engn Chennai 600036 Tamil Nadu India

Recently, there has been extensive progress in developing autostereoscopic platforms for display purposes to present real-world 3D scenes. light fields are the best emerging choice for computational multi-view autostereoscopic displays since they provide an optimized solution to support direction-dependent outputs simultaneously without sacrificing the resolution. We present a novel light field representation, coding and streaming scheme that efficiently handles large tensor data. Intrinsic redundancies in light field subsets are eliminated through low-rank representation using Tucker decomposition with tensor sketching for various ranks and sketch dimension parameters, making it ideal for streaming and transmission. Apart from removing spatial redundancies, the approximated light field is used to construct a Fourier disparity layers representation to further exploit other non-linear, temporal, intra and inter-view correlations present among the approximated sub-aperture images. Four scanning or view prediction patterns are utilized and the subsets in each pattern hierarchically construct the FDL representation and synthesize subsequent views. Iterative refinement and encoding with HEVC are followed by the final light field reconstruction. The complete end-to-end processing pipeline can flexibly work for multiple bitrates and is adaptable for a variety of multi-view autostereoscopic platforms. The compression performance of the proposed scheme is analyzed on real light fields. We achieved substantial bitrate savings compared to state-of-the-art codecs, while maintaining good reconstruction quality.

关键词： light fields Three-dimensional displays Encoding Image coding Tensors Bit rate Image reconstruction light field coding Fourier disparity layers HEVC low-rank tensor decomposition streaming tensor sketching

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Rate-distortion optimized interactive light field streaming

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IEEE TRANSACTIONS ON MULTIMEDIA 2007年第4期9卷 813-825页

作者： Ramanathan, Prashant Kalman, Mark Girod, Bernd AOL LLC San Francisco CA 94140 USA Stanford Univ Stanford CA 94305 USA

High-quality, photorealistic image-based rendering datasets are typically too large to download entirely before viewing, even when compressed. It is more suitable to instead stream the required image data to a remote user who can start interacting with the dataset immediately. This paper presents an interactive light field streaming system and proposes packet scheduling for transmitting the encoded image data in a rate-distortion optimized manner. An interactive light field streaming system must have low user latency. The system presented in this paper predicts the future user viewing trajectory to mitigate the effects of the low-latency constraints. Experimental results show that view prediction can improve performance, and that this improvement is limited by the prediction accuracy. The proposed packet scheduling algorithm considers network conditions and rate-distortion cost, knowledge of sent and received images, and the distortion for a set of images, to optimize the rendered image quality for the remote user. Rate-distortion optimized scheduling can be implemented either at the receiver or the sender. It is shown that this rate-distortion optimized packet scheduling can significantly improve performance over a heuristic scheduling approach. Experimental results also show that the encoding prediction dependency structure affects streaming performance both through the compression efficiency of the encoding and also through any decoding dependencies that may be introduced.

关键词： image-based rendering image coding image communication interactive streaming light field coding light field streaming light fields rate-distortion optimized streaming

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Supporting Wider Baseline light fields in JPEG Pleno With a Novel Slanted 4D-DCT coding Mode

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IEEE ACCESS 2023年 11卷 28294-28317页

作者： de Carvalho, Murilo Bresciani Pagliari, Carla L. Alves, Gustavo de O. E. Schretter, Colas Schelkens, Peter Pereira, Fernando da Silva, Eduardo A. B. Univ Fed Fluminense TET CTC BR-24220900 Niteroi Brazil Inst Mil Engn PEE PGED IME BR-22290270 Rio De Janeiro Brazil Univ Fed Rio de Janeiro PEE COPPE DEL BR-21941901 Rio De Janeiro Brazil Vrije Univ Brussel Dept Elect & Informat B-1050 Brussels Belgium Imec Dept Digital & User Centr Solut B-3001 Leuven Belgium Univ Lisbon Inst Super Tecn P-1049001 Lisbon Portugal Inst Telecomunicacoes P-1049001 Lisbon Portugal

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 standard for static light fields, which has specified two coding modes, named 4D-Transform and 4D-Prediction. While the first offers better compression performance for smaller baseline light fields, the second excels for larger baseline light fields. This paper intends to propose a novel light field coding mode, the Slanted 4D-Transform coding mode, which extends the 4D-Transform coding mode based on the conventional 4D-DCT, to offer better compression performance than both the available JPEG Pleno coding modes, independently of the baseline. The key idea is to apply first to each 4D block in the light field an adaptive, hierarchical geometric transformation, which makes the data in the block more energy-compaction friendly for the following 4D-DCT. The rate-distortion performance results show that the proposed Slanted 4D-Transform codec is able to outperform both the already standardized JPEG Pleno coding modes, showing BD-Rates gains of 31.03% and 28.30% for the 4D-Transform and 4D-Prediction modes, respectively, thus implying that a single coding mode can efficiently code all types of light fields.

关键词： light fields Encoding Transform coding Standards Cameras Transforms Image coding JPEG Pleno standard light field coding 4D transform mode 4D-DCT slant transform

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Plenoptic 2.0 Intra coding Using Imaging Principle

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IEEE TRANSACTIONS ON BROADCASTING 2022年第1期68卷 110-122页

作者： Jin, Xin Jiang, Fan Li, Lingjun Zhong, Tingting Tsinghua Univ Shenzhen Int Grad Sch Shenzhen 518055 Peoples R China

Plenoptic 2.0 videos that are captured by focused plenoptic cameras outperform the traditional plenoptic videos with higher spatial resolution of rendered subaperture images and more effective light field sampling. However, its distinct imaging principle causes different pixel intensity distribution and complex macropixel structures, which results in ineffectiveness in coding them using the existing plenoptic video compression methods. Thus, a novel compression method is proposed in this paper to dramatically improve the intra prediction efficiency for multi-focus plenoptic 2.0 video coding. It consists of two new intra prediction modes: imaging-principle-guided static prediction (ISP) and imaging-principle-guided zoomed prediction (IZP). In ISP, the prediction candidates spatially positioned by plenoptic 2.0 imaging principle are weighted by minimizing boundary error to generate the predicted samples. In IZP, the spatial positions and scales of the prediction candidates vary according to the focusing status and the focal length of the microlens that generates the pixels in the prediction candidates. The combination of two modes generalizes plenoptic 2.0 video coding for multi-focus plenoptic cameras. The proposed approach outperforms high efficiency video coding (HEVC) standard by an average of 15.37% bitrate reduction under All Intra configuration. It also outperforms other state-of-the-art methods with obvious compression efficiency improvements.

关键词： Plenoptic 2.0 video coding HEVC/H.265 intra prediction light field coding

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An Analysis of 3D Point Cloud Reconstruction from light field Images 6

An Analysis of 3D Point Cloud Reconstruction from Light Fiel...

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6th International Conference on Image Processing Theory, Tools and Applications (IPTA)

作者： Perra, Cristian Murgia, Francesca Giusto, Daniele Univ Cagliari I-09124 Cagliari Italy

ISBN: (纸本)9781467389105

Current methodologies for the generation of 3D point cloud from real world scenes rely upon a set of 2D images capturing the scene from several points of view. Novel plenoptic cameras sample the light field crossing the main camera lens creating a light field image. The information available in a plenoptic image must be processed in order to render a view or create the depth map of the scene. This paper analyses a method for the reconstruction of 3D models. The reconstruction of the model is obtained from a single image shot. Exploiting the properties of plenoptic images, a point cloud is generated and compared with a point cloud of the same object but generated with a different plenoptic camera.

关键词： light field coding Plenoptic coding Lossless coding Image compression

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