Light field image coding based on hybrid data representation

This paper proposes a novel efficient light field coding approach based on a hybrid data representation. Current state-of-the-art light field coding solutions either operate on micro-images or sub-aperture images. Consequently, the intrinsic redundancy that exists in light field images is not fully exploited, as is demonstrated. This novel hybrid data representation approach allows to simultaneously exploit four types of redundancies: i) sub-aperture image intra spatial redundancy, ii) sub-aperture image inter-view redundancy, iii) intra-micro-image redundancy, and iv) inter-micro-image redundancy between neighboring micro-images. The proposed light field coding solution allows flexibility for several types of baselines, by adaptively exploiting the most predominant type of redundancy on a coding block basis. To demonstrate the efficiency of using a hybrid representation, this paper proposes a set of efficient pixel prediction methods combined with a pseudo-video sequence coding approach, based on the HEVC standard. Experimental results show consistent average bitrate savings when the proposed codec is compared to relevant state-of-the-art benchmarks. For lenslet light field content, the proposed coding algorithm outperforms the HEVC-based pseudo-video sequence coding benchmark by an average bitrate savings of 23%. It is shown for the same light field content that the proposed solution outperforms JPEG Pleno verification models MuLE and WaSP, as these codecs are only able to achieve 11% and -14% bitrate savings over the same HEVC-based benchmark, respectively. The performance of the proposed coding approach is also validated for light fields with wider baselines, captured with high-density camera arrays, being able to outperform both the HEVC-based benchmark, as well as MuLE and WaSP.info:eu-repo/semantics/publishedVersio

Investigation of the spread bovine tuberculosis in Southern Brazil by Whole-genome sequencing.

Mycobacterium bovis is the causal agent of bovine tuberculosis, one of the most important diseases currently facing the cattle industry worldwide. Tracing the source of M. bovis infections that result from movement of livestock is an important tool to understand the epidemiology of bovine tuberculosis (bTB) and defining control/eradication strategies. Whole genome sequencing (WGS) provides a higher resolution than other established typing methods and greatly improves the definition of the regional localization of M. bovis types. Cultures of M. bovis were isolated from 58 bovine granulomatous tissue using conventional methods (Stonebrink medium) from eight dairy farms of the State of Rio Grande do Sul, Southern Brazil. The isolates were sequenced using both llumina technologies NextSeq 500 System and HiSeqX System

Haemoglobin Kenitra Identified in a Portuguese Man with Type 2 Diabetes and Pheochromocytoma

info:eu-repo/semantics/publishedVersio

Structural characterization and release profile of omega-3 fatty-acids encapsulated in nanoemulsions

Omega-3 (-3) fatty-acids are functional compounds with various benefits such as reduction of cardiovascular diseases. However, these fatty acids degrade quickly, present low water solubility and an unpleasant aroma, which make essential their encapsulation. The encapsulation (e.g. nanoemulsion production) process can change structural properties, which can affect the behavior of the system when applied to food matrices and within the gastrointestinal tract. The objective of this work was to characterize oil-in-water bio-based nanoemulsions with -3 using lactoferrin as a natural emulsifier, when submitted to different drying processes. Nanoemulsions were produced using high-pressure homogenization (5 cycles, 20,000 psi) using 2 % (w/w) lactoferrin and 5 % (w/w) -3. Nanoemulsions were dried by nanospray-drying (Nano Spray dryer B-90HP, Buchi) and freeze-drying methods. Physical and morphological properties were evaluated using dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. Circular dichroism (CD) and FTIR-ATR were used to assess possible structural and chemical changes after dry treatments. Moreover, -3 release profile was studied in ethanol (20 % and 50 % (v/v)) at 25 ºC (simulation of food matrices) and at pH 7.4 and pH 2 at 37 ºC (simulation of different gastrointestinal phases). DLS results showed that original size (170 nm) and zeta-potential (+30 mV) of nanoemulsions was not achieved after nanospray-drying process probably caused by protein agglomeration. CD and FTIR-ATR results revealed lactoferrin structural modifications after drying processes as well as a reduction of -helix and -sheet content, being this effect more evident on nanospray-drying samples. FTIR-ATR results showed shifts of the amide I and amide II bands in both drying processes samples. At 20 % ethanol, -3 began to release after 48h which could allow nanoemulsions incorporation in food products such as ice cream and mayonnaise. This work provides useful information to design nanoemulsions aiming lipophilic compound encapsulation for food applications.info:eu-repo/semantics/publishedVersio

Light field image coding with flexible viewpoint scalability and random access

This paper proposes a novel light field image compression approach with viewpoint scalability and random access functionalities. Although current state-of-the-art image coding algorithms for light fields already achieve high compression ratios, there is a lack of support for such functionalities, which are important for ensuring compatibility with different displays/capturing devices, enhanced user interaction and low decoding delay. The proposed solution enables various encoding profiles with different flexible viewpoint scalability and random access capabilities, depending on the application scenario. When compared to other state-of-the-art methods, the proposed approach consistently presents higher bitrate savings (44% on average), namely when compared to pseudo-video sequence coding approach based on HEVC. Moreover, the proposed scalable codec also outperforms MuLE and WaSP verification models, achieving average bitrate saving gains of 37% and 47%, respectively. The various flexible encoding profiles proposed add fine control to the image prediction dependencies, which allow to exploit the tradeoff between coding efficiency and the viewpoint random access, consequently, decreasing the maximum random access penalties that range from 0.60 to 0.15, for lenslet and HDCA light fields.info:eu-repo/semantics/acceptedVersio

Light field image coding using high order prediction training

This paper proposes a new method for light field image coding relying on a high order prediction mode based on a training algorithm. The proposed approach is applied as an Intra prediction method based on a two-stage block-wise high order prediction model that supports geometric transformations up to eight degrees of freedom. Light field images comprise an array of micro-images that are related by complex perspective deformations that cannot be efficiently compensated by state-of-the-art image coding techniques, which are usually based on low order translational prediction models. The proposed prediction mode is able to exploit the non-local spatial redundancy introduced by light field image structure and a training algorithm is applied on different micro-images that are available in the reference region aiming at reducing the amount of signaling data sent to the receiver. The training direction that generates the most efficient geometric transformation for the current block is determined in the encoder side and signaled to the decoder using an index. The decoder is therefore able to repeat the high order prediction training to generate the desired geometric transformation. Experimental results show bitrate savings up to 12.57% and 50.03% relatively to a light field image coding solution based on low order prediction without training and HEVC, respectively.info:eu-repo/semantics/acceptedVersio

Light field image coding: objective performance assessment of Lenslet and 4D LF data representations

State-of-the-art light field (LF) image coding solutions, usually, rely in one of two LF data representation formats: Lenslet or 4D LF. While the Lenslet data representation is a more compact version of the LF, it requires additional camera metadata and processing steps prior to image rendering. On the contrary, 4D LF data, consisting of a stack of sub-aperture images, provides a more redundant representation requiring, however, minimal side information, thus facilitating image rendering. Recently, JPEG Pleno guidelines on objective evaluation of LF image coding defined a processing chain that allows to compare different 4D LF data codecs, aiming to facilitate codec assessment and benchmark. Thus, any codec that does not rely on the 4D LF representation needs to undergo additional processing steps to generate an output comparable to a reference 4D LF image. These additional processing steps may have impact on the quality of the reconstructed LF image, especially if color subsampling format and bit depth conversions have been performed. Consequently, the influence of these conversions needs to be carefully assessed as it may have a significant impact on a comparison between different LF codecs. Very few in-depth comparisons on the effects of using existing LF representation have been reported. Therefore, using the guidelines from JPEG Pleno, this paper presents an exhaustive comparative analysis of these two LF data representation formats in terms of LF image coding efficiency, considering different color subsampling formats and bit depths. These comparisons are performed by testing different processing chains to encode and decode the LF images. Experimental results have shown that, in terms of coding efficiency for different color subsampling formats, the Lenslet LF data representation is more efficient when using YUV 4:4:4 with 10 bit/sample, while the 4D LF data representation is more efficient when using YUV 4:2:0 with 8 bit/sample. The “best” LF data representation, in terms of coding efficiency, depends on several factors which are extensively analyzed in this paper, such as the objective metric that is used for comparison (e.g., average PSNR-Y or average PNSR-YUV), the type of LF content, as well as the color format. The maximum objective quality is also determined, by evaluating the influence of each block from each processing chain in the objective quality of the reconstructed LF image. Experimental results show that, when the 4D LF data representation is not used the maximum achieved objective quality is lower than 50 dB, in terms of average PSNR-YUV.info:eu-repo/semantics/acceptedVersio

Optimized reference picture selection for light field image coding

This paper proposes a new reference picture selection method for light field image coding using the pseudo-video sequence (PVS) format. State-of-the-art solutions to encode light field images using the PVS format rely on video coding standards to exploit the inter-view redundancy between each sub-aperture image (SAI) that composes the light field. However, the PVS scanning order is not usually considered by the video codec. The proposed solution signals the PVS scanning order to the decoder, enabling implicit optimized reference picture selection for each specific scanning order. With the proposed method each reference picture is selected by minimizing the Euclidean distance to the current SAI being encoded. Experimental results show that, for the same PVS scanning order, the proposed optimized reference picture selection codec outperforms HEVC video coding standard for light field image coding, up to 50% in terms of bitrate savings.info:eu-repo/semantics/acceptedVersio

Experimentação participativa na produçãode erva-doce (Foeniculum vulgare Mill.) em bases ecológicas no agreste sergipano.

bitstream/CPATC/19593/1/Doc-110.pd