High Compression Rate Research Articles

A General Model for the Design of Efficient Sign-Coding Tools for Wavelet-Based Encoders

Traditionally, it has been assumed that the compression of the sign of wavelet coefficients is not worth the effort because they form a zero-mean process. However, several image encoders such as JPEG 2000 include sign-coding capabilities. In this paper, we analyze the convenience of including sign-coding techniques into wavelet-based image encoders and propose a methodology that allows the design of sign-prediction tools for whatever kind of wavelet-based encoder. The proposed methodology is based on the use of metaheuristic algorithms to find the best sign prediction with the most appropriate context distribution that maximizes the resulting sign-compression rate of a particular wavelet encoder. Following our proposal, we have designed and implemented a sign-coding module for the LTW wavelet encoder, to evaluate the benefits of the sign-coding tool provided by our proposed methodology. The experimental results show that sign compression can save up to 18.91% of bit-rate when enabling sign-coding capabilities. Also, we have observed two general behaviors when coding the sign of wavelet coefficients: (a) the best results are provided from moderate to high compression rates; and (b) the sign redundancy may be better exploited when working with high-textured images.

A novel echocardiographic-derived classification after LAA closure can accurately predict incomplete ostial closure and significant peri-device leaks

Abstract Background The assessment of residual peri-device leaks (PDL) after percutaneous left atrial appendage closure (LAAC) remains crucial in the post-procedural management. Clinical significance of PDL is still poorly understood and echocardiographic recognition of PDL remains challenging. This study aimed to verify a novel proposed echocardiographic classification for prediction of clinically significant PDL following LAAC. Methods We retrospectively evaluated our echocardiographic data of 72 patients who underwent percutaneous LAAC at the University Hospital Jena between September 2015 - 2018. All echo images were transferred to a workstation for offline analysis by two independent investigators. Total number of studies was 127. We proposed a morphological classification of LAA devices (Fig. 1A-C) based on the amount of echodensity and luceny inside the devices into three types: type A: homogenous echodensity in 0, 45, 90 and 135°; indicating completely thrombosed device, type B with inhomogeneous echo-lucencies (<50% of device) and type C: partially thrombosed device with echo-lucencies >50% of total, which we labeled “ice-cream cone” sign. Each type was then matched to the degree of PDL and other clinical and paraclinical parameters. Results Tab.1 shows patient's characteristics. PDL was found in 21% of patients. Four patients showed regression of PDL after 160 days. Patients with type C had the most percentage of PDL in three types at 6 months follow-up (type A: 7%, type B: 33%, type C 100%, p<0.001). Device size in patients with type C was largest in three types (type A: 25.9±3.6mm, type B: 25.8±3.4mm, type C 29.8±3.0mm, type A vs. B, p=0.018; type B vs. C, p=0.007). Mean compression rate after 45 days was 21±9.3% in type A vs. 14±7.4% in type C (p=0.022). Ice cream sign showed a sensitivity of 53.1%, specificity of 100% and positive predictive value of 100% for prediction of PDL. Conclusion Our data demonstrate that: 1) This novel classification irrespective of anticoagulation regimen, can accurately discriminate among various degrees of PDL, in such that type C or “ice cream sign” has a very high positive predictive value for PDL (100%). 2) Type A, the ideal type, is associated with smaller landing zones and a higher compression rate. Funding Acknowledgement Type of funding source: None

High compression rate, based on the RLS adaptive algorithm in progressive image transmission

The purpose of this paper is to develop a novel method based on recursive least squares (RLS) adaptive algorithm for progressive image transmission (PIT). The image is divided into non-overlapping blocks. Having an agreed vector sequence between the transmitter and the receiver, each block is related to a regressive model. Meanwhile, at the transmitter the blocks are estimated using the RLS algorithm. The high correlation between error vectors, regarding to the RLS execution, causes a very high compression rate in their transmission. The error vectors at the receiver are used to run the RLS algorithm and to estimate the image in a same manner. The method is easy to implement with a low computational complexity and achieves high quality, compared to other well-known methods. In comparison with its counterparts, simulation results show how efficient the proposed method is.

Effects of positive dispatcher encouragement on the maintenance of bystander cardiopulmonary resuscitation quality.

Background: Implementation of dispatcher-assisted cardiopulmonary resuscitation (DACPR) has increased the likelihood of bystander CPR upon cardiac arrest. However, the quality of CPR has been found to be very low. In this study, we aimed to compare CPR quality between the current DACPR practices and the interventional instruction of adding verbal encouragement from the dispatcher.Methods: In this randomized controlled trial, we recruited adult (age ≥18) laypersons who were non-health care providers and had never received any previous verified CPR training. They were randomly selected to perform DACPR using metronome sounds (mDACPR) as per the standard protocol, or DACPR with metronome sounds along with human encouragement (mheDACPR). The ratio of accurate compression rate, depth, and complete release for each CPR phase was examined.Results:Sixty nine records (34, mDACPR; 35, mheDACPR) were taken. The median proportion of accurate chest compression rate was initially 29.5% with mDACPR, and significantly increased to 71% after 2 minutes of CPR administration (P = .046). However, the median ratio of accurate chest compression depth was 61.5% in the first phase, and significantly decreased to 0% in the last phase (P < .001). In contrast, for the mheDACPR group, a high accurate compression rate was maintained throughout the 2 minutes of CPR administration (91%, 100%, 100%, 100%).Conclusion: To maintain the quality of CPR administered by bystanders, continuous feedback and repeated human encouragement should be provided during DACPR. Active dispatcher intervention reduces the time required to reach an appropriate CPR rate and allows for the maintenance of accurate compression rates.

DICOM compression and decompression method using double cone

The increase of information in the medical environment caused by digital imaging settings is notable. The search and use of these technological tools aimed at medicine require a greater availability of storage, generating increasing costs. In medicine, together with information technology, there is a format of images used in exams, diagnostics, tomography, among others. This format, entitled DICOM, was created in order to standardize uses in medical devices for exam answers. An open question is the compression of DICOM data, in order to maintain quality, maintaining high rates of compression. This presents a new method for compressing and decompressing DICOM data using a dual cone bijector function and a video codec, called DC (Double Cone). This work offers 3 changes to the DC method (DC1, DC2 and DC3). The results obtained with a new technique show that the compression, although with loss, has a similarity index very close to the original image (SSIM = 0.99), and an accuracy ratio equal to 69.51, in the better case. The better performing version was the DC2.

Preparation and characterization of porous zircon aggregates by granulation method: Roles of the polymorphism of Al2O3

In this paper, eight zircon granules were prepared by granulation method, using zircon powders as raw material, α-Al2O3 and γ-Al2O3 as additives and sodium carboxymethyl cellulose (CMC) as binder, respectively. Then, the influence of α-Al2O3 and γ-Al2O3 addition on phase composition, lattice parameters, microstructure and physical characterization were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results reveal that Al2O3 could influence the Al2O3–ZrSiO4 system by reacting with SiO2 and dissolving into the zircon crystal lattice. The changing of the crystal lattice and the formation of mullite were the main influence factor. The zircon aggregate with 3.0 wt% γ-Al2O3 rendered an optimal apparent porosity of 25.2 %, a high cylinder compressive strength retention rate of 55.1 %, a relatively homogeneous pore size distribution and a smaller changing in lattice parameters.

Towards optimisation of rolling process of potato dough: Effect of processing on the microstructure and the mechanical properties

The quality of potato chips is highly dependent on the mechanical properties of the dough sheet produced prior to frying. It has been well established that poor mechanical properties result in fragile dough sheets and associated high product wastage. However, the effect of the rolling process on the mechanical properties of the dough is unknown so the optimum rolling process can only be obtained via a trial and error approach. This work reports for the first time the effects of dry flake size and rolling parameters on the mechanical performance of potato dough sheets. The laboratory scale rolling setup used a 10 cm roller diameter with a 0.2 mm gap height. Furthermore, an experimental method was developed enabling rigorous tensile testing of fragile potato dough sheets. The mechanical performance of the potato dough sheets was anisotropic, as the Young's modulus and strength were 35% and 57% higher across the rolling direction than those along the rolling direction, respectively. The formability, i.e. the ability to form a coherent sheet of the potato dough is improved by using smaller dry flakes (<500 μm). However, further decrease in the flakes size had no effect on the mechanical behaviour of potato dough sheets, i.e. flakes with diameter smaller than 212 μm showed similar tensile response to flakes smaller than 500 μm. Rolling the dough increases the coherence and the strength of the potato dough sheets, but also introduces defects orientated across the rolling direction which decrease the strength if the dough is rolled too many times. For example, sheets rolled for seven passes showed over 100% improvement in failure stress comparing to sheets rolled for five passes, but when the sheets were rolled for the eighth pass, the failure stress dropped by 17%. Due to the viscoelasticity of the dough, both the tensile modulus and strength of the sheets are higher when tested at higher strain rate. In addition, at higher strain rate, the defects in the sheets did not have enough time to grow, as evidenced by a lower scatter in failure stress. A method to obtain an optimum production condition has been identified, which will lead to fewer production interruptions due to dough breakage, and reduced waste. • Investigation on the effect of rolling process on the mechanical behaviour of thin potato dough sheets. • First research on the dry potato flake size-potato dough sheet property relationship. • Design of a novel test gear to perform tensile tests on potato dough sheets and other fragile materials. • Study on the mechanical behaviour of potato dough sheets after rolling process with high compression rate. • Microstructure observation to identify how the change in potato dough microstructure affects the mechanical performance.

Fractal image compression with adaptive quadtree partitioning and non-linear affine map

Fractal image compression techniques are now very popular for its high compression rates and resolution independence property. However, the qualities of decoded images of the existing techniques are not satisfactory. An adaptive partitioning scheme can improve the image quality significantly. These existing adaptive techniques use linear affine maps during encoding that have limited pixel intensity approximation ability. In order to increase the image quality further, non-linear affine maps can be used that generalizes the pixel intensity approximation and generates much better approximation. Here, a fractal based technique for image compression using non-linear contractive affine maps has been proposed that applies adaptive quadtree partitioning to partition image in a context dependent way to enhance decoded image quality. The technique partitions twice an image to be compressed to obtain collection of ranges and domains and finds the highest matching non-linear affine transformed domain of each range. The corresponding affine parameters are kept in the compressed file. However, a range may be broken into sub-ranges using adaptive quadtree partitioning for unavailability of enough matching domains and repeat the same on those. The comparative results show that the proposed technique greatly improves the decoded image quality than existing techniques and also maintains the high compression ratios. Two variants have also been proposed that improve compression ratio of the proposed technique without any degradation of image quality using loss-less coding.

Compressed sensing for reduced hardware footprint in medical ultrasound

In this work, a compressed sensing method to reduce hardware complexity of ultrasound imaging systems is proposed and experimentally verified. We provide clinical evaluation of the method with a possible high compression rates (up to 64 RF signals compressed into a single channel on receive) which uses elastic net estimation for decoding stage. This allows a reduction in size and power consumption of the front-end electronics with only a minor loss in image quality. We demonstrate an 8-fold receive channel count reduction with a 3.16 dB and 3.64 dB mean absolute error for gallbladder and kidney images, respectively, as well as 7.4% increase in the contrast-to-noise ratio for kidney images and 0.1% loss in the contrast-to noise ratio for gallbladder images, on average. The proposed method may enable a fully portable ultrasonic device with virtually no loss in image quality as compared to a full size clinical scanner to be constructed.

Modification of Equations of State in the Metastable Region for High-speed Vapor Compression

A modification of the well-known wide-range equations of state of Nigmatulin–Bolotnova is proposed for describing the high-speed adiabatic-compression of vapor of tetradecane in the metastable region in physically consistent way. The modification is based on taking into account the effect of delay of vapor condensation processes under high compression rate. It is useful for studying various phenomena associated with high-speed compression of vapor of tetradecane when the compression is close to adiabatic. It can, in particular, be applied to investigating high-speed collapse of cavitation bubbles in tetradecane. The technique of the proposed modification can also be used for a similar correction of other equations of state built on the basis of the generalized Born–Mayer potential.

Four-Dimensional Cone-Beam Computed Tomography Image Compression Using Video Encoder for Radiotherapy.

Four dimensional cone-beam computed tomography (4D-CBCT) images were widely used for patient positing and target localization in radiotherapy. As consisting of multiple CBCT sets, it needs more time and space for data transferring and storage. In this study the feasibility of applying video coding algorithms for 4D-CBCT image compression was investigated. Prior to compression 4D-CBCT images were arranged in an order based on breathing phase or slice location for input sequence of video encoder. Median filtering was applied to suppress noise and artifact of 4D-CBCT for improved image quality. Three popular video coding algorithms (Motion JPEG 2000, Motion JPEG AVI, and MPEG-4) were tested and their performances were evaluated on a publicly available 4D-CBCT database. The average compression ratio of MPEG-4 was 135, while the values of Motion JPEG AVI and Motion JPEG 2000 were 16 and 7, respectively. The compression rate of two ordering methods was comparable and the location-based ordering method was slightly higher. With pre-processing of median filtering, the inter-frame similarity of input sequence was improved and the resulting compression rate was increased. MPEG-4 provided extremely higher compression rate for 4D-CBCT images. The ordering method based on slice location resulted in higher compression rate than the ordering method based on breathing phase. The median filtering was effective in improving inter-frame similarity and resulted in higher compression rate. The video coding algorithms are not only applicable for 4D image modalities but also feasible for serial 3D image modalities.

Launching Vehicle Acoustic Data Compression Study Using Lossy Audio Formats

The field of data compression has evolved over the last decades. In this way, several techniques to reduce the amount of acquired data from the sensor required to be transmitted have been developed. Those techniques are usually classified by lossless or lossy, where, for the lossless techniques, all acquired data is recovered, while the lossy techniques introduce errors to these data. Each of these techniques presents advantages and drawbacks, being the analyst responsible for choosing the appropriate technique for a specific application. This work presents a comparative study using lossy audio formats to be applied on a launch vehicle on-board acoustic data. The Opus format achieved a higher compression rate in comparison with standard compression techniques by saving up to 254 times the required amount of data to be transmitted through a telemetry link on launcher vehicle, and the lowest discrepancy from original data measured by the mean square error metric.

A Study on Source Device Attribution Using Still Images

Images are acquired and stored digitally these days. Image forensics is a science which is concerned with revealing the underlying facts about an image. The universal approaches provide a general strategy to perform image forensics irrespective of the type of manipulation. Identification of acquisition device is one of the significant universal approach. This review paper aims at analyzing the different types of device identification approaches. All research papers aiming camera and mobile detection using image analysis were acquired and then finally 60 most suitable papers were included. Out of these, 32 states of art papers were critically analyzed and compared. As every research starts with the literature review such analysis is significant. This is the first attempt for source camera and source mobile detection evaluation as per the authors knowledge. The authors have concluded that the Accuracy rate of Lens Aberration based detection techniques deteriorates when the different source camera from same brand were under consideration. The performance of color filter array Based Detection techniques dropped when the post processing operation were used on images. These techniques were vulnerable to high compression rate for JPEG images.

Non-uniqueness of critical solid fraction considering boundary conditions and strain-rate effects

The critical solid fraction (ϕJ), which marks the transition between the solid and liquid phases in the jamming diagram, is influenced by several factors. In this study, the dependency of ϕJ on strain rate and boundary conditions is examined through discrete element method simulations considering a frictionless polydisperse granular system. Different approaches are used to determine ϕJ. The observed boundary effect is due to the nonuniform solid fraction distribution induced by the clustering of particles close to rigid-wall boundaries at high compression rates. The solid fraction distribution within the sample in the rigid-wall simulations approaches that in the periodic-boundary simulations as the compression rate decreases. With increasing compression rate, the major force transmission network contains fewer mechanically stable particles and a less stable force transmission network. This causes jamming of the granular assembly at a lower solid fraction. These force transmission networks, however, are fragile and disintegrate quickly upon relaxation.

3D Medical image compression using the quincunx wavelet coupled with SPIHT

&lt;p&gt;Medical imaging is a growing field due to the development of digital technologies that produce 3D and even 4D data. The counterpart to the resolution offered by these voluminal images resides in the amount of gigantic data, hence the need for compression. This article presents a new coding scheme dedicated to 3D medical images. The originality of our approach lies in the application of the Quinqunx wavelet transform coupled with the SPIHT encoder on a database of medical images. This approach achieves much higher compression rates, while maintaining a very acceptable visual quality.&lt;/p&gt;

QuadStack: An Efficient Representation and Direct Rendering of Layered Datasets.

We introduce QuadStack, a novel algorithm for volumetric data compression and direct rendering. Our algorithm exploits the data redundancy often found in layered datasets which are common in science and engineering fields such as geology, biology, mechanical engineering, medicine, etc. QuadStack first compresses the volumetric data into vertical stacks which are then compressed into a quadtree that identifies and represents the layered structures at the internal nodes. The associated data (color, material, density, etc.) and shape of these layer structures are decoupled and encoded independently, leading to high compression rates (4× to 54× of the original voxel model memory footprint in our experiments). We also introduce an algorithm for value retrieving from the QuadStack representation and we show that the access has logarithmic complexity. Because of the fast access, QuadStack is suitable for efficient data representation and direct rendering. We show that our GPU implementation performs comparably in speed with the state-of-the-art algorithms (18-79 MRays/s in our implementation), while maintaining a significantly smaller memory footprint.

Effect of Water Repellents on Hygroscopicity and Dimensional Stability of Densified Fir and Aspen Woods

This study investigated the effect of pre-impregnation with water-repellent agents on the hygroscopicity and dimensional stability of fir (Abies bornmulleriana Mattf.) and aspen (Populus tremula L.) woods. After pre-vacuum treatment, the samples were impregnated at atmospheric pressure with paraffin, linseed oil and styrene, and then densified at compression rates of 20 % and 40 % at 120, 150 and 180 °C. The results showed that water repellents significantly affected the hygroscopicity and dimensional stability of the densified wood samples. Compression recovery rate (CRR), thickness swelling (TS), equilibrium moisture content (EMC), and water absorption (WA) values of the densified samples decreased with impregnation pretreatments. The linseed oil treatment gave more positive CRR and TS results than paraffin. Lower EMC and WA values were found in the paraffin-treated samples. However, the most successful results for all tested properties were determined in the styrene pretreated samples in which hygroscopicity decreased and dimensional stability increased (especially for aspen) due to increases in the compression rate and temperature related to densification conditions. In the styrene pretreated samples, the high temperature (180 °C) and compression rate (40 %) significantly reduced CRR, TS, EMC and WA, total dimensional stability was nearly achieved and the water repellent effectiveness was close to 100 %.

RETRACTED ARTICLE: Lossless medical image compression algorithm using tetrolet transformation

In many analytical applications the reuse of medical images plays an important role. In order to store the images, image compression is the technique used to save the storage space and the storage time. The image compression is used in image transmission for the fast transmission. Also in health care sector the compressed image helps to make it complete computerized. The noise interference is the major problem in the image compression. Thus some compression techniques are used to remove the noise added in medical images. This will improve the quality of the compressed image. In image compression the medical image can be processed in deep degree by de-noising, edge preservation and high compression rate. The aim of the paper is develop an efficient computational tetrolet transform, which can be used in lossless compression. For analysis purpose various wavelet techniques are used and result is compared with this techniques. From the analysis it is inferred that by proposed technique is able to achieve a high quality images with low noise.

A Noble Double-Dictionary-Based ECG Compression Technique for IoTH

The Internet-of-Things (IoT) healthcare system monitors a patients’ condition and takes preventive measures in case of an emergency. The electrocardiogram (ECG) that measures the electrical activity of the heart is one of the important health indicators. Thanks to the wearable technology, nowadays, we can even measure the ECG using smart portable devices and send via a wireless channel. However, this wireless transmission has to minimize both energy and memory consumption. In this article, we propose CULT—an ECG compression technique using unsupervised dictionary learning. Our method achieves a high compression rate due to the essence of dictionary learning and is immune to the noise by integrating discrete cosine transformation. Moreover, it continuously expands the dictionary when the unseen pattern occurs and refines the dictionary when new input arrives, by imposing the double dictionary scheme. We show that our method has a better performance by comparing it with the other existing approaches.

An efficient framework for increasing image quality using DRN Bi-layer enfolded compressor

Lossy /lossless image compression technique results will either improve the quality of image with reduced compression ratio or degrades the image with better compression ratio. But on dealing with the combined lossy/lossless techniques, they provide the output with better image quality and high compression rate, however, the techniques failed to obtain better efficiency due to less predictive nature. Hence, to acquire an image having better compression rate with improved predictive nature, a novel framework is introduced in our proposed work. It uses a Deep Residual Network Bi-Layer Enfolded Compressor (DRN-BLEC) to enhance the image quality. In order to obtain better compression rate, the Mexican Meyer Hat Wavelet Transform (MMHWT) is used. Similarly, the well knowledge quantization is achieved by utilizing DRN for learning; it is then followed by the Lloyds quantization technique that groups the feature values by quantizing it, which in turn boost-up the resolution of the image. Consequently with DRN, the process of encoding and decoding doesn’t requires to be done separately since two residual layer of the DRN are trained to encode and decode the images, which thereby reduces the time required for compression process. Thus a compressed image with high resolution is obtained without redundancy, moreover with high compression ratio. The architecture of the DRN-BLEC is implemented in MATLAB and the respective result structure is validated.