High Degree Of Compression Research Articles

Improving Efficiency of Entropy Coding Method in Modern Video Compression Standards

Modern video coding standards have high coding efficiency, but the encoding performance has to be improved to meet the growing multimedia applications. The paper deals with the entropy encoding methods and algorithms in video coding standard H.264/AVC and H.265/HEVC. Context-based Adaptive Variable Length Coding (CAVLC) for the H.264/AVC standard was originally designed for lossy video coding, and as such does not yield adequate performance for lossless video coding. Context-Adaptive Binary Arithmetic Coding (CABAC) is a method of entropy coding first introduced in H.264/AVC and now used in the standard H.265/HEVC. While it provides high coding efficiency, the data dependencies in H.264/AVC CABAC make it challenging to parallelize and thus, limit its throughput. Accordingly, during the standardization of entropy coding for HEVC, both coding efficiency and throughput were considered. Based on an analysis of their advantages and disadvantages, a method called the entropy coding algorithm using the enumerative coding of the hierarchical approach is proposed. The proposed algorithm consists of the Context-Adaptive Binary Arithmetic Coding algorithm and the enumerative coding algorithm with a hierarchical approach. The proposed algorithm is tested in the Visual C ++ development environment on various test video sequences. The results of the experiments showed a greater efficiency of coding of multimedia data (the proposed one reduces on average up to 15% of the storage volume compared to the traditional CABAC method), while the method requires a longer coding time (approximately twice). The proposed method can be recommended for use in telecommunication systems for storage, transmission and processing of multimedia data, where a high degree of compression is required first.

Optimized JPEG 2000 Compression for Efficient Storage of Histopathological Whole-Slide Images

Background: Whole slide images (WSIs, digitized histopathology glass slides) are large data files whose long-term storage remains a significant cost for pathology departments. Currently used WSI formats are based on lossy image compression alogrithms, either using JPEG or its more efficient successor JPEG 2000. While the advantages of the JPEG 2000 algorithm (JP2) are commonly recognized, its compression parameters have not been fully optimized for pathology WSIs. Methods: We defined an optimized parametrization for JPEG 2000 image compression, designated JP2-WSI, to be used specifically with histopathological WSIs. Our parametrization is based on allowing a very high degree of compression on the background part of the WSI while using a conventional amount of compression on the tissue-containing part of the image, resulting in high overall compression ratios. Results: When comparing the compression power of JP2-WSI to the commonly used fixed 35:1 compression ratio JPEG 2000 and the default image formats of proprietary Aperio, Hamamatsu, and 3DHISTECH scanners, JP2-WSI produced the smallest file sizes and highest overall compression ratios for all 17 slides tested. The image quality, as judged by visual inspection and peak signal-to-noise ratio (PSNR) measurements, was equal to or better than the compared image formats. The average file size by JP2-WSI amounted to 15, 9, and 16 percent, respectively, of the file sizes of the three commercial scanner vendors’ proprietary file formats (3DHISTECH MRXS, Aperio SVS, and Hamamatsu NDPI). In comparison to the commonly used 35:1 compressed JPEG 2000, JP2-WSI was three times more efficient. Conclusions: JP2-WSI allows very efficient and cost-effective data compression for whole slide images without loss of image information required for histopathological diagnosis.

Detonability of white dwarf plasma: turbulence models at low densities

We study the conditions required to produce self-sustained detonations in turbulent, carbon-oxygen degenerate plasma at low densities. We perform a series of three-dimensional hydrodynamic simulations of turbulence driven with various degrees of compressibility. The average conditions in the simulations are representative of models of merging binary white dwarfs. We find that material with very short ignition times is abundant in the case that turbulence is driven compressively. This material forms contiguous structures that persist over many ignition times, and that we identify as prospective detonation kernels. Detailed analysis of prospective kernels reveals that these objects are centrally-condensed and their shape is characterized by low curvature, supportive of self-sustained detonations. The key characteristic of the newly proposed detonation mechanism is thus high degree of compressibility of turbulent drive. The simulated detonation kernels have sizes notably smaller than the spatial resolution of any white dwarf merger simulation performed to date. The resolution required to resolve kernels is 0.1 km. Our results indicate a high probability of detonations in such well-resolved simulations of carbon-oxygen white dwarf mergers. These simulations will likely produce detonations in systems of lower total mass, thus broadening the population of white dwarf binaries capable of producing Type Ia supernovae. Consequently, we expect a downward revision of the lower limit of the total merger mass that is capable of producing a prompt detonation. We review application of the new detonation mechanism to various explosion scenarios of single, Chandrasekhar-mass white dwarfs.

Application of digital volume correlation to study the efficacy of prophylactic vertebral augmentation

BackgroundProphylactic augmentation is meant to reinforce the vertebral body, but in some cases it is suspected to actually weaken it. Past studies only investigated structural failure and the surface strain distribution. To elucidate the failure mechanism of the augmented vertebra, more information is needed about the internal strain distribution. This study aims to measure, for the first time, the full-field three-dimensional strain distribution inside augmented vertebrae in the elastic regime and to failure. MethodsEight porcine vertebrae were prophylactically-augmented using two augmentation materials. They were scanned with a micro-computed tomography scanner (38.8μm voxel resolution) while undeformed, and loaded at 5%, 10%, and 15% compressions. Internal strains (axial, antero-posterior and lateral-lateral components) were computed using digital volume correlation. FindingsFor both augmentation materials, the highest strains were measured in the regions adjacent to the injected cement mass, whereas the cement-interdigitated-bone was less strained. While this was already visible in the elastic regime (5%), it was a predictor of the localization of failure, which became visible at higher degrees of compression (10% and 15%), when failure propagated across the trabecular bone. Localization of high strains and failure was consistent between specimens, but different between the cement types. InterpretationThis study indicated the potential of digital volume correlation in measuring the internal strain (elastic regime) and failure in augmented vertebrae. While the cement-interdigitated region becomes stiffer (less strained), the adjacent non-augmented trabecular bone is affected by the stress concentration induced by the cement mass. This approach can help establish better criteria to improve vertebroplasty.

Influence of image compression on the interpretation of spectral-domain optical coherence tomography in exudative age-related macular degeneration

To evaluate the effect of image compression of spectral-domain optical coherence tomography (OCT) images in the examination of eyes with exudative age-related macular degeneration (AMD). Thirty eyes from 30 patients who were diagnosed with exudative AMD were included in this retrospective observational case series. The horizontal OCT scans centered at the center of the fovea were conducted using spectral-domain OCT. The images were exported to Tag Image File Format (TIFF) and 100, 75, 50, 25 and 10% quality of Joint Photographic Experts Group (JPEG) format. OCT images were taken before and after intravitreal ranibizumab injections, and after relapse. The prevalence of subretinal and intraretinal fluids was determined. Differences in choroidal thickness between the TIFF and JPEG images were compared with the intra-observer variability. The prevalence of subretinal and intraretinal fluids was comparable regardless of the degree of compression. However, the chorio-scleral interface was not clearly identified in many images with a high degree of compression. In images with 25 and 10% quality of JPEG, the difference in choroidal thickness between the TIFF images and the respective JPEG images was significantly greater than the intra-observer variability of the TIFF images (P=0.029 and P=0.024, respectively). In OCT images of eyes with AMD, 50% of the quality of the JPEG format would be an optimal degree of compression for efficient data storage and transfer without sacrificing image quality.

Hybrid DWT-DCT Algorithm for Digital Image Watermarking and Compression Applications

Digital image watermarking is process of adding some information in image in form of text, image and logo for the purpose of owner identification and security. This information may be in visible or in invisible form. So that anyone can be extracted that info when required for a particular purposes. The main obstacle in extraction process of watermark information is the different-2 attacks perform of watermarked image. These attacks degrade the watermark information embedded in watermarked image. Sometimes they affected so much as the watermark information will be destroyed. Digital image in their raw form require a more amount of storage capacity. Considering the important role played by digital imaging and video, it is necessary to develop a system that produces high degree of compression while preserving critical image information. There is various transformation techniques used for data compression. Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) are the most commonly used transformation. DCT has high energy compaction property and requires less computational resources. On the other hand, DWT is multi resolution transformation. In this work, we propose a hybrid DWT-DCT algorithm for image compression and reconstruction taking benefit from the advantages of both algorithms. The algorithm performs the Discrete Cosine Transform (DCT) on the Discrete Wavelet Transform (DWT) coefficients. Simulations have been conducted on several natural, benchmarks, medical and endoscopic images. The simulation results show that the proposed hybrid DWT-DCT algorithm performs much better than the standalone JPEG-based DCT, DWT, and WHT algorithms in terms of Peak Signal to Noise Ratio (PSNR). The new scheme reduces false contouring and blocking artifacts significantly. The rate distortion analysis shows that for a fixed level of distortion, the number of bits required to transmit the hybrid coefficients would be less than those required for other schemes Furthermore, the proposed algorithm is also compared with the some existing hybrid algorithms. The comparison results show that, the proposed hybrid algorithm has better performance and reconstruction quality.

PE-CPE blends and their graphene oxide nanocomposites with reduced low temperature brittleness

The low-temperature flexibility of polyethylene (PE)–chlorinated polyethylene (CPE) blends and their composites with a small amount of graphene oxide filler was studied. Quantitative height variation in the AFM images, rheological as well as fracture analyses were employed to gain insights into the generation of flexibility in the matrix phase. The semi-crystalline CPE (CPE25) polymer did not induce viscoelastic behavior at temperatures lower than the glass transition temperature of PE, whereas the amorphous CPE (CPE35) had completely different behavior. The samples with CPE35 could not be sufficiently hardened even at −180 °C and remained too soft for cryosectioning. Therefore, compression, which results in a 30–60 % reduction in length along the cutting direction with no change in the dimension perpendicular to it, was very prominent for both thin section and block face of the sample. The composites had even higher degree of compression due to additional effect of weak filler matrix interactions and as a consequence, the topographical variations led to filler pull out during sectioning. It was also confirmed using the rheological analysis that composites (and blends with 10 % CPE35 content) had phase immiscibility as CPE phase was suspected to concentrate near the graphene oxide phase leading to generation of chlorine-rich phases. The addition of graphene oxide did not lead to reduced flexibility and the composites also retained the modulus similar to pure polymer. The mechanical fracture of the samples also confirmed the flexibility of the CPE containing blends and composites as these samples were still flexible at −195 °C.

Cylindrically and spherically symmetrical rapid intense compression of an ideal perfect gas with adiabatic exponents from 1.001 to 3

The problem of the rapid intense cylindrically or spherically symmetrical compression of an ideal (non-viscous and non-heat-conducting) perfect gas with different adiabatic exponents is considered. We mean by rapid and intense a compression in a time much less than the time taken for the sound wave to propagate through the uncompressed target up to temperatures and densities as high as desired. It is found that the solution previously obtained with a focused non-self-similar compression wave at the point where the shock wave is reflected from the axis or centre of symmetry (henceforth the centre of symmetry) holds for adiabatic exponents not exceeding 1.9092 and 1.8698 respectively in the cylindrical and spherical cases. It was not possible to construct a complete solution with focusing at the centre of symmetry for gases with higher adiabatic exponents. On the other hand, one can focus the compression waves into a cylinder or sphere of as small, but finite, radius as desired at the instant of arrival on them, for example, of a special characteristic or reflected shock wave of the Guderley problem. It is shown that for high degrees of compression, the time dependences of the coordinates of the pistons which produce such focusing, and of the gas density on them are close to power laws.

Perceptually adaptive spread transform image watermarking scheme using Hadamard transform

The present paper proposes a digital image watermarking scheme using the characteristics of the human visual system (HVS), spread transform technique and statistical information measure. Spread transform (ST) scheme is implemented using the transform coefficients of both the host and the watermark signal. Watermark embedding strength is adaptively adjusted using frequency sensitivity, luminance, contrast and entropy masking of HVS model. The choice of Hadamard transform as watermark embedding domain offers several advantages, such as low loss in image information (higher image fidelity), greater reliability of watermark detection and higher data hiding capacity at high degree of compression. Performance of the proposed method is compared with a number of recently reported watermarking schemes based on spread spectrum (SS) and quantization index modulation (QIM).

Разработка осецентробежного компрессора для энергетического двигателя малой мощности

It is created the high-pressure, low flow rate compressor for the power engine of low power. In ten axial and one centrifugal stage the high degree of compression and a sufficient level of efficiency for compressors of such class is received. Ways of the further increase of efficiency of the axial-centrifugal compressor are offered.

Structure, thermodynamics, and diffusion in CaAl 2Si 2O 8 liquid from first-principles molecular dynamics

We have performed first-principles molecular dynamics simulations of CaAl 2Si 2O 8 (anorthite) liquid at pressures up to 120 GPa and temperatures of 3000, 4000 and 6000 K. At the lowest degrees of compression the liquid is seen to accommodate changes in density through decreasing the abundance of 3- and 4-membered rings, while increases in coordination of network forming cations take effect at somewhat higher degrees of compression. Results are fit to a fundamental thermodynamic relation with 4th order finite strain and 1st order thermal variable expansions. Upon compression by a factor of two, the Grüneisen parameter ( γ) is found to increase continuously from 0.35 to 1.10. Weak temperature dependence in γ is thermodynamically consistent with a slight decrease in isochoric heat capacity ( C V ), for which values of between 4.4 and 5.2 Nk B are obtained, depending on the temperature. Pressure and temperature dependence of self-diffusivities is found to be well represented by an Arrhenius relation, except at 3000 K and pressures lower than 5 GPa, where self-diffusivities of Si, Al, and O increase with pressure. Analysis of the lifetimes of individual coordination species reveals that this phenomenon arises due to the disproportionately high stability of 4-fold coordinated Si, and to a lesser extent 4-fold coordinated Al. Our results represent a marked improvement in accuracy and reliability in describing the physics of CaAl 2Si 2O 8 liquid at deep mantle pressures, pointing the way to a general thermodynamic model of melts at extreme pressures and temperatures relevant to planetary-scale magma oceans and deep mantle partial melting.

Temporal Envelope of Time-Compressed Speech Represented in the Human Auditory Cortex

Speech comprehension relies on temporal cues contained in the speech envelope, and the auditory cortex has been implicated as playing a critical role in encoding this temporal information. We investigated auditory cortical responses to speech stimuli in subjects undergoing invasive electrophysiological monitoring for pharmacologically refractory epilepsy. Recordings were made from multicontact electrodes implanted in Heschl's gyrus (HG). Speech sentences, time compressed from 0.75 to 0.20 of natural speaking rate, elicited average evoked potentials (AEPs) and increases in event-related band power (ERBP) of cortical high-frequency (70-250 Hz) activity. Cortex of posteromedial HG, the presumed core of human auditory cortex, represented the envelope of speech stimuli in the AEP and ERBP. Envelope following in ERBP, but not in AEP, was evident in both language-dominant and -nondominant hemispheres for relatively high degrees of compression where speech was not comprehensible. Compared to posteromedial HG, responses from anterolateral HG-an auditory belt field-exhibited longer latencies, lower amplitudes, and little or no time locking to the speech envelope. The ability of the core auditory cortex to follow the temporal speech envelope over a wide range of speaking rates leads us to conclude that such capacity in itself is not a limiting factor for speech comprehension.

Compositional effect on the pressure derivatives of bulk modulus of silicate melts

Although the bulk moduli ( K T 0) of silicate melts have a relatively narrow range of values, the pressure derivatives of the isothermal bulk modulus ( K T 0 ′) can assume a broad range of values and have an important influence on the compositional dependence of the melt compressibility at high pressure. Based on the melt density data from sink/float experiments at high pressures in the literature, we calculate K T 0 ′ using an isothermal equation of state (EOS) (e.g., Birch–Murnaghan EOS and Vinet EOS) with the previously determined values of room-pressure density ( ρ 0) and room-pressure bulk modulus ( K T 0). The results show that best estimates of K T 0 ′ vary considerably from ~ 3 to ~ 7 for different compositions. K T 0 ′ is nearly independent of Mg # (molar Mg/(Mg + Fe)), but decreases with SiO 2 content. Hydrous melts have anomalously small K T 0 ′ leading to a high degree of compression at high pressures. For anhydrous melts, K T 0 ′ is ~ 7 for peridotitic melts, ~ 6 for picritic melts, ~ 5 for komatiitic melts, and ~ 4 for basaltic melts.

Pulse dynamics in inhomogeneous optically coupled amplifying optical fibers with high-order dispersion effects taken into account

The evolution of the envelope of a two-mode wave packet in an inhomogeneous-over-length amplifying optical fiber is analyzed with the third-order dispersion effects taken into account, the presence of which leads to modulations of one or both edges of the wave packet. High degrees of compression of the pulse and the complete suppression of oscillations of its time envelope can be attained by an appropriate choice of the type of inhomogeneity of the dispersion parameters.

Life Beyond Uncompressed TIFF: Alternative File Formats for the Storage of Master Image Files

The TIFF uncompressed file format is a widely accepted standard for storing master images of digitisation projects. As in the Koninklijke Bibliotheek, The National Library of the Netherlands (KB) the scale of these projects is rising rapidly, the need for an alternative, compressed file format is felt. This paper contains a summary of a research project in which four alternative file formats - JPEG 2000 Part 1 lossless and lossy, PNG, JPEG and TIFF LZW - have been described and tested. Four consequences of a choice for either of the formats have been described: consequences for storage, image quality, long term durability and functionality. In the final recommendations these consequences were weighed against three reasons the KB distinguishes for wanting to store master images:1. Substitution (JPEG 2000 Part 1 lossless or PNG)2. Redigitalisation is no option (Visual lossless JPEG 2000 Part 1 lossy or JPEG)3. Master file is the basis for access (JPEG and JPEG 2000 lossy with higher degrees of compression)

Optimization of the cycle life performance of VRLA batteries, working under high rate, partial state of charge (HRPSOC) conditions

On hybrid vehicle applications, batteries must work in a rather low state of charge (SOC), in order to be able to recover as much of the regenerative braking energy as possible. Usually SOC values around 60% are used, which promotes the development of new unexpected failure modes not previously found, mainly associated with heavy sulphation of the negative plates. In order to try to optimise the cycle life performance to the point of making these batteries a real alternative for the application of hybrid vehicles, a series of tests have been undertaken, aimed to optimise the key parameters that from previous experience are known to determine life duration in high rate low state of charge (HRPSOC) conditions. Previous works have been focused on trying to determine the optimum composition of positive and negative active material, concerning paste density in the positive, and additives in negative. In order to overcome the deleterious effect of heavy sulphation in negative plates on cycle life, the use of conductivity enhancers additives such as graphite has been proposed. The objective of this project is to optimize the performance of the glass microfiber separators, in order to maintain a high degree of compression in the group, as well as to avoid acid stratification and development of short circuits along the battery life. To do this, different glass microfiber separators with inert additives, as well as different fiber composition have been tested. Results obtained up to now, indicate a remarkable good performance of the VRLA batteries with the new separators containing very fine fiberglass and silica fillers as an additive.

Influence of addition of Zenural 70, urea and Min-A-Zel Plus on chemical composition and quality of whole maize plant silage

The influence of addition of Zenural 70, urea and Min-A-Zel Plus on chemical composition and quality of whole maize plant silage with different degree of compression was investigated in the paper. Experiment was two-factorial (2x3) with three replications, where factor A was a degree of compression (A, = 680 g/dm?; A2 = 550 g/dm?), while factor B was an additive type (Decontrol; B2=5 g/kg urea+2 g/kg Min-A-Zel Plus; B3=5 g/kg Zenural 70). Chemical analyses showed that with the addition of Zenural 70 and urea there was significant increase of pH value, total protein, mineral ammonia and soluble nitrogen content. The type of additive had no significant effect on production of lactic, acetic and butyric acid, while in silages with higher degree of compression (680 g/dm3) there was significantly more butyric acid. All silages were graded first class according to DLG and Flieg method, with the exception of lower compressed silage with added urea and Min-A-Zel Plus, which according to Flieg was second class. According to Zelter method, silages with added Zenural 70 were II and III class, while treatments with added urea and Min-A-Zel Plus were IV and V class. .

Protostellar Jet Collisions Reduce the Efficiency of Outflow‐Driven Turbulence in Molecular Clouds

We present a series of numerical studies of the interaction of colliding radiative, hydrodynamic young stellar outflows. We study the effect of the collision impact parameter on the acceleration of ambient material and the degree to which the flow is isotropized by the collision as a mechanism for driving turbulence in the parent molecular cloud. Our results indicate that the high degree of compression of outflow material, achieved through radiative shocks near the vertex of the interaction, prevents the redirected outflow from spraying over a large spatial region. Furthermore, the collision reduces the redirected outflow's ability to entrain and impart momentum into the ambient cloud. Consideration of the probabilities of outflow collisions leads us to conclude that individual low-velocity fossil outflows are the principle coupling between outflows and the cloud.

Asynchronous rate control for multi-object videos

Object-based coding can potentially achieve a higher degree of compression and better visual quality. The objects in a scene are not always synchronous, that is, they have different temporal resolutions. In some applications, it is more efficient to transmit asynchronous objects with different temporal rates so as to achieve a better tradeoff between temporal and spatial resolutions. This requires to balance the qualities of individual objects while ensuring an overall visual quality with a given bit rate. This paper proposes a rate control algorithm for multiple video object encoding, which is suitable for both synchronous and asynchronous transmissions. The algorithm aims to maximize scene quality with an accurate bit rate, while efficiently handling buffer fullness. Using an efficient bit allocation strategy, the algorithm achieves accurate target bit rates, provides good coding quality, and decreases buffer overflow/underflow. The proposed algorithm also allows flexible priority adjustment among multiple objects to ensure overall better visual perception. Designed primarily for asynchronous objects, the algorithm treats the synchronous objects as a special case. Experimental results demonstrate that, when giving suitable asynchronous video object planes rates, the proposed algorithm achieves good temporal-spatial tradeoff while yielding accurate rate regulation and effective buffer control.

Edge Defection Prediction by Using Wavelet Compression

Digital image have been expanding in usage. The importance of image compression algorithms have been increased, to produce smaller file size with a lower computational requirement. The wavelet transform offers a natural decomposition of images at multiple resolutions, since the wavelet transform can decompose images into various multiresolution subbands, where the correlation exists. A novel technique for image compression by taking advantage of correlation is addressed. It is based on predictive edge detection from the LL band of the lowest resolution level to predict the edge in the LH, HL and HH bands in the higher resolution level. If the coefficient is predictive as an edge it is preserved, otherwise it is discarded. In the decoder, the location of the preserved coefficients can also be found as in the encoder. Results showed that photo images give a higher degree of compression compared with the satellite images, due to the information in the satellite images is higher than in the photo images.