Mittuniversitetet

In recent years, several deep learning-based architectures have been proposed to compress Light Field (LF) images as pseudo video sequences. However, most of these techniques employ conventional compression-focused networks. In this paper, we introduce a version of a previously designed deep learning video compression network, adapted and optimized specifically for LF image compression. We enhance this network by incorporating an in-loop filtering block, along with additional adjustments and fine-tuning. By treating LF images as pseudo video sequences and deploying our adapted network, we manage to address challenges presented by the unique features of LF images, such as high resolution and large data sizes. Our method compresses these images competently, preserving their quality and unique characteristics. With the thorough fine-tuning and inclusion of the in-loop filtering network, our approach shows improved performance in terms of Peak Signal-to-Noise Ratio (PSNR) and Mean Structural Similarity Index Measure (MSSIM) when compared to other existing techniques. Our method provides a feasible path for LF image compression and may contribute to the emergence of new applications and advancements in this field.

Immersive imaging technologies provide an enhanced user experience for visual applications and are getting ready for commonplace use by the industry and the general populace. In particular, light field is a promising technology that enables the capture and reproduction of real light rays from the scene, which can provide a backbone for immersive telecommunication and telepresence applications. Nevertheless, there are still many challenges in transmitting and reproducing light field data. This paper proposes a spherical light field dataset that can be used as a foundation for developing telepresence applications. The Spherical Light Field Database (SLFDB) consists of a light field of 60 views captured with an omnidirectional camera in 20 scenes. To show the usefulness of the proposed database, we provide two use cases: compression and viewpoint estimation. The initial results validate that the publicly available SLFDB will benefit the scientific community.

Light field (LF) imaging captures both spatial and angular information, which is essential for applications such as depth estimation, view synthesis, and post-capture refocusing. However, the efficient processing of this data, particularly in terms of compression and encoding/decoding time, presents challenges. We propose a Variational Autoencoder (VAE)-based framework to disentangle the spatial and angular features of light field images, focusing on fast and efficient compression. Our method uses two separate sub-encoders-one for spatial and one for angular features-to allow for independent processing in the latent space, which facilitates more streamlined compression workflows. Evaluations on standard light field datasets demonstrate that our approach reduces encoding and decoding time significantly, with a slight trade-off in Rate-Distortion (RD) performance, making it suitable for real-time applications.

Light fields (LF) technology enables the capture and reproduction of a 3D scene accurately, which enhances visual experience in various applications. The sheer volume of multiplicity of the captured views creates logistical problems in both storage and data transmission, which makes LF compression crucial. Even though many LF compression techniques have been proposed and evaluated in recent years, the leading-edge learning-based approaches have not been subject to the same level of scrutiny. This paper presents a subjective quality assessment study on four different LF compression methods, including two learning-based LF compression methods, which have not been studied before from a subjective quality point of view. For this purpose, subjective opinion scores were collected from viewers in two different universities for a cross-lab study. The results indicate that the learning-based compression methods have different behavior in their rate-distortion curves, and that there is room for improvement for learning-based methods. A qualitative analysis also shows that their artifact structures are different from conventional ones. The results highlight the need for a perceptual objective quality metric that takes different types of artifacts into account. The obtained subjective quality database (MiX-LFQDB) is made public to support further research in this area: \url{https://doi.org/10.5281/zenodo.16778670

Light field (LF) imaging captures spatial and angular information, offering a 4D scene representation enabling enhanced visual understanding. However, high dimensionality and redundancy across spatial and angular domains present major challenges for compression, particularly where storage, transmission bandwidth, or processing latency are constrained. We present a novel Variational Autoencoder (VAE)-based framework that explicitly disentangles spatial and angular features using two parallel latent branches. Each branch is coupled with an independent hyperprior model, allowing more precise distribution estimation for entropy coding and finer rate-distortion control. This dual-hyperprior structure enables the network to adaptively compress spatial and angular information based on their unique statistical characteristics, improving coding efficiency. To further enhance latent feature specialization and promote disentanglement, we introduce a mutual information-based regularization term that minimizes redundancy between the two branches while preserving feature diversity. Unlike prior methods relying on covariance-based penalties prone to collapse, our information-theoretic regularizer provides more stable and interpretable latent separation. Experimental results on publicly available LF datasets demonstrate our method achieves strong compression performance, yielding an average BD-PSNR gain of 2.91 dB over HEVC and high compression ratios (e.g., 200:1). Additionally, our design enables fast inference, with a total end-to-end time over 19x faster than the JPEG Pleno standard, making it well-suited for real-time and bandwidth-sensitive applications. By jointly leveraging disentangled representation learning, dual-hyperprior modeling, and information-theoretic regularization, our approach offers a scalable, effective solution for practical light field image compression.

Recent advancements in learned light field (LF) image compression highlight the advantages of modeling spatial and angular redundancies using deep generative models. Among these, Variational Autoencoders (VAEs) have shown strong potential in learning compact latent representations of LF data. However, many existing approaches rely on simple uniform quantization and basic entropy coding, which limits compression efficiency in practical applications. This paper introduces DUALF-C, a lightweight and retrainingfree compression pipeline that augments pretrained VAE-based LF compression models using structured post-encoding transformations. The proposed framework integrates bitplane slicing, latent channel reordering, non-uniform quantization, and patch-based vector quantization to improve bitrate efficiency while preserving reconstruction quality. Experimental evaluations demonstrate that DUALF-C significantly reduces bit-per-pixel (BPP) without degrading image quality, making it a practical solution for bandwidthconstrained immersive imaging systems.