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At least 703 records · Page 39Linked to original sources
PubMed2006

On the mathematical reconstruction of two dimensional plants.

A set of 10, chosen medicinal plants (some of them with a reputation as remedies for tuberculosis) has been investigated through Partitioned Iterated Function Systems-Semi Fractals with Angle (PIFS-SFA) coding, Lempel, Ziv, Welch with quantization and noise (LZW-QN) compression, and surface density statistics (f(alpha)-SDS) discrimination techniques. The final outcomes of this quantitative analysis were, firstly: the linear ordering of the plants in question accompanied by the hope that it reflects their medical significance, secondly: the mathematical representation of each of the plants, and thirdly: the impressive compression achieved, leading to remarkable computer memory saving, and still permitting successful pattern recognition i.e., proper identification of the plant from the compressed image.

Algorithms↗
PubMed2005

Compound image compression for real-time computer screen image transmission.

We present a compound image compression algorithm for real-time applications of computer screen image transmission. It is called shape primitive extraction and coding (SPEC). Real-time image transmission requires that the compression algorithm should not only achieve high compression ratio, but also have low complexity and provide excellent visual quality. SPEC first segments a compound image into text/graphics pixels and pictorial pixels, and then compresses the text/graphics pixels with a new lossless coding algorithm and the pictorial pixels with the standard lossy JPEG, respectively. The segmentation first classifies image blocks into picture and text/graphics blocks by thresholding the number of colors of each block, then extracts shape primitives of text/graphics from picture blocks. Dynamic color palette that tracks recent text/graphics colors is used to separate small shape primitives of text/graphics from pictorial pixels. Shape primitives are also extracted from text/graphics blocks. All shape primitives from both block types are losslessly compressed by using a combined shape-based and palette-based coding algorithm. Then, the losslessly coded bitstream is fed into a LZW coder. Experimental results show that the SPEC has very low complexity and provides visually lossless quality while keeping competitive compression ratios.

Algorithms↗
PubMed2004

Perceptually tuned JPEG coder for echocardiac image compression.

In this work, we propose an efficient framework for compressing and displaying medical images. Image compression for medical applications, due to available Digital Imaging and Communications in Medicine requirements, is limited to the standard discrete cosine transform-based joint picture expert group. The objective of this work is to develop a set of quantization tables (Q tables) for compression of a specific class of medical image sequences, namely echocardiac. The main issue of concern is to achieve a Q table that matches the specific application and can linearly change the compression rate by adjusting the gain factor. This goal is achieved by considering the region of interest, optimum bit allocation, human visual system constraint, and optimum coding technique. These parameters are jointly optimized to design a Q table that works robustly for a category of medical images. Application of this approach to echocardiac images shows high subjective and quantitative performance. The proposed approach exhibits objectively a 2.16-dB improvement in the peak signal-to-noise ratio and subjectively 25% improvement over the most useable compression techniques.

Algorithms↗
PubMed2005

Three-dimensional display and arbitrary region interactive segmentation of high-resolution virus capsids from cryo-electron microscopy single particle reconstruction.

Recent advances in cryo-electron microscopy (cryo-EM) instrumentation and single particle reconstruction have created opportunities for high-throughput and high-resolution three-dimensional (3-D) structure determination of virus. In order to visualize and effectively understand the 3-D structure, we present a display method based on surface rendering, which has the function of 3-D arbitrary region interactive segmentation and quantitative analysis, and integrate them into a software package called CEM-3DVDSS (cryo-EM 3-D virus display and arbitrary region segmentation system). CEM-3DVDSS consists of a complete set of modular programs for 3-D display and segmentation of icosahedral virus, which is organized under a graphical user interface and provides user-friendly options. First, we convert volume data in the MRC format obtained by cryo-EM single particle reconstruction to the format of our own software; in the preprocessing step, the original volume data are compressed and a better vector dimension is found for controlling the speed and detail of display. Then, the new volume data can be displayed and segmented using CEM-3DVDSS. We demonstrate the applicability of CEM-3DVDSS by displaying the 3-D structures of 2.5 nm (resolution) BmCPV (Bombyx mori cytoplasmic polyhedrosis virus), 2.5 nm CSBV (Chinese Sacbrood bee virus) and 1.4 nm C6/36DNV (Densonucleosis virus). As a result, both the 3-D display speed and signal-to-noise ratio of CEM-3DVDSS are improved compared with the original method, and the segmentation results become precise and more intact with additional function of quantitative analysis of 3-D structure.

Animals↗
PubMed1999

Adaptation of bulk constitutive equations to insoluble monolayer collapse at the air-water interface.

A constitutive equation based on stress-strain models of bulk solids was adapted to relate the surface pressure, compression rate, and temperature of an insoluble monolayer of monodendrons during collapse at the air-water interface. A power law relation between compression rate and surface pressure and an Arrhenius temperature dependence of the steady-state creep rate were observed in data from compression rate and creep experiments in the collapse region. These relations were combined into a single constitutive equation to calculate the temperature dependence of the collapse pressure with a maximum error of 5 percent for temperatures ranging from 10 degrees to 25 degrees C.

Air↗
PubMed1988

Saccular aneurysm of the transverse thoracic aorta detected by transesophageal echocardiography.

A patient with a saccular aneurysm of the thoracic aortic arch presented with severe right ventricular failure due to pulmonary artery compression. Contradictory data were derived from computed tomography, pulmonary isotope perfusion scan and cardiac catheterization. Transesophageal echocardiography revealed a saccular aneurysm which compressed the main pulmonary artery and gave access to a fistulous connection to the left pulmonary artery. Surgery confirmed these findings.

Aorta, Thoracic↗