Integer wavelet transform for embedded lossy to lossless image compression.

The use of the discrete wavelet transform (DWT) for embedded lossy image compression is now well established. One of the possible implementations of the DWT is the lifting scheme (LS). Because perfect reconstruction is granted by the structure of the LS, nonlinear transforms can be used, allowing efficient lossless compression as well. The integer wavelet transform (IWT) is one of them. This is an interesting alternative to the DWT because its rate-distortion performance is similar and the differences can be predicted. This topic is investigated in a theoretical framework. A model of the degradations caused by the use of the IWT instead of the DWT for lossy compression is presented. The rounding operations are modeled as additive noise. The noise are then propagated through the LS structure to measure their impact on the reconstructed pixels. This methodology is verified using simulations with random noise as input. It predicts accurately the results obtained using images compressed by the well-known EZW algorithm. Experiment are also performed to measure the difference in terms of bit rate and visual quality. This allows to a better understanding of the impact of the IWT when applied to lossy image compression.

Rank-order polynomial subband decomposition for medical image compression.

In this paper, the problem of progressive lossless image coding is addressed. A nonlinear decomposition for progressive lossless compression is presented. The decomposition into subbands is called rank-order polynomial decomposition (ROPD) according to the polynomial prediction models used. The decomposition method presented here is a further development and generalization of the morphological subband decomposition (MSD) introduced earlier by the same research group. It is shown that ROPD provides similar or slightly better results than the compared coding schemes such as the codec based on set partitioning in hierarchical trees (SPIHT) and the codec based on wavelet/trellis-coded quantization (WTCQ). Our proposed method highly outperforms the standard JPEG. The proposed lossless compression scheme has the functionality of having a completely embedded bit stream, which allows for data browsing. It is shown that the ROPD has a better lossless rate than the MSD but it has also a much better browsing quality when only a part of the bit stream is decompressed. Finally, the possibility of hybrid lossy/lossless compression is presented using ultrasound images. As with other compression algorithms, considerable gain can be obtained if only the regions of interest are compressed losslessly.

Train-pedestrian accidents.

The aim of this study was to evaluate the injury pattern, morbidity, and mortality in pedestrians involved in train accidents. The study was performed in the Hacettepe University School of Medicine, Turkey. Hospital records of 41 cases who were hit by train between the period of 1985-97 were evaluated. Age, gender, mechanism of injury (falling from train, hit by train), suicide attempts, pre-existing illnesses, RTS (Revised Trauma Score) and mortality were evaluated. Sixty-eight per cent (n = 28) of the victims were male. The mean age was 32 (9-72) years. Fifty-nine per cent of the victims had fallen from the train. The rate of suicide attempt was 22% (n = 9). The mean RTS was 10+/-3.6. Survivors had better RTS (11+/-2) than nonsurvivors (3.5+/-2.5) (p < 0.0001, 95% CI = 6.0-9.5). Extremity fractures and lower extremity amputations were frequently encountered. The mortality rate was 17%. The mortality rate was high in victims who were hit by the train (p = 0.00013). Suicide attempts carry a high mortality rate (p = 0.0001). Six mortalities were seen in nine documented suicide attempts. It is concluded that train-pedestrian injuries represent a different type of trauma. The mortality rate in suicide attempts is high. RTS lower than 11 and being hit by train are associated with high mortality.

Prospective, double-blind, comparative fast-tracking trial in an academic emergency department during a period of limited resources.

The aim of this study was to determine the effectiveness of 'fast-tracking' in an academic emergency department (ED) during a period of limited resources and space constraints. This was a prospective, double-blind, comparative clinical trial. Fast-tracking was applied every other day between 08.00 and 17.30 hours. Patients meeting fast-tracking criteria, which were determined as allergy, dyspepsia, hypertension, urinary tract infection, urolithiasis, gastroenteritis, upper airway infection, minor lacerations, and soft tissue injuries with no sign or symptom of life-threatening illness or acute abdomen, were treated by a designated fast-tracking team. In the alternate days fast-tracking was not done, and the patients having the same criteria were recorded and followed as the control group. ED length of stays were determined for each patient, and at time of discharge a questionnaire was applied to determine patient satisfaction. Follow-up was performed by telephone survey at the 5th day of discharge. The median length of stay was 36 minutes for the fast-tracked group compared with 63 minutes for the control group. The application of fast-tracking decreased ED length of stay and improved patient satisfaction in patients presenting with allergy, dyspepsia, upper airway infection, minor laceration, and soft tissue injury, but not in patients with gastroenteritis, urinary tract infection, hypertension, and urolithiasis. The rate of follow-up was 81% (n = 217), and there were no complications or hospitalizations to another hospital. It is concluded that fast-tracking is an applicable and useful system in an academic ED with limited resources, and decreases ED length of stay and improves patient satisfaction in a selected group of patients. Determination of fast tracking criteria must be individualized for each hospital according to resources. Additionally, fast-tracking seems to be safe when performed under strict criteria for patient selection.

Prospects for telediagnosis using ultrasound.

Ultrasound imaging is currently used as a primary diagnostic tool in cardiology, abdominal disorders, pulmonary medicine, trauma, and obstetrics. Because of its relatively low capital and operating costs as well as its growth potential, it represents one of the major diagnostic modalities of future health care. However, the use of ultrasonography as a mobile and powerful modality is controlled by the availability of a highly skilled technician to acquire the images and an experienced physician to interpret them. This paper discusses the technology required to increase the availability of a diagnosing physician by employing telerobotics. With this technology, the physician can guide the motion of the transducer by the technician from a remote location. Thus, the physician controls the examination and renders the diagnosis. It is shown that communication lines at 1.5 Mbits/s (T-1 speed) can, with appropriate compression, support both real-time viewing of the ultrasound images and telerobotic manipulation of the transducer. The incremental costs of telediagnosis for an examination are estimated to be a small fraction of the base charges and significantly less than the expense of bringing a physician to a remote location or transporting a patient to a regional medical center. Telediagnosis can, in addition, provide benefits from immediate interpretation and consultation that cannot be duplicated using store-and-forward scenarios.

The flying cylinder: a new algorithm for filament recognition in noisy stereo images.

We present a new method of automatic 3D filament representation which uses stereo micrographs to reconstruct three-dimensional trajectories of filament-like objects as DNA molecules. The method deals with low contrasted and noisy images, as obtained from cryovitrified samples by means of electron microscopy. The three-dimensional information is extracted from skeletizing simultaneously both images of a given stereo-pair, instead of processing them separately. The main advantages of the technique are reproducibility and speed, compared to the reconstruction done by manual registration, i.e., clicking on the stereo micrographs.

Multiscale analysis for singularity detection in pulmonary microvascular pressure transients.

This paper addresses the problem of pulmonary microvascular pressure estimation. The "why" and "how" of multiscale approaches in the context of singularity detection are discussed. From a linear viewpoint, the scalogram technique and the multiresolution representation for singularity detection are discussed in general under the wavelet framework. A technique as well as a criterion for the segmentation and the extraction of the region of interest or the optimal scale is proposed. A new nonlinear multiscale technique for singularity detection is also proposed. This multiscale representation is based on rank order filters and on mathematical morphology operators in particular. A scaling parameter is introduced for such operators as in the linear continuous wavelet transform leading to what we call morpholograms. Experiments performed on pulmonary artery pressure transients illustrate how the proposed technique can give a synopsis of the signal characteristics through the scales.

New trends in image data compression.

This paper gives an overview of a number of advanced techniques for image compression, which are under investigation in the Signal Processing Laboratory at the Swiss Federal Institute of Technology of Lausanne. Various applications ranging from High definition television (HDTV) to multimedia will be discussed. In particular, systems based on subband decomposition, edge based representation, as well as symmetries will be presented.

Image coding.

The digital representation of an image requires a very large number of bits. The goal of image coding is to reduce this number, as much as possible, and reconstruct a faithful duplicate of the original picture. Early efforts in image coding, solely guided by information theory, led to a plethora of methods. The compression ratio reached a saturation level around 10:1 a couple of years ago. Recent progress in the study of the brain mechanism of vision and scene analysis has opened new vistas in picture coding. Directional sensitivity of the neurones in the visual pathway combined with the separate processing of contours and textures has led to a new class of coding methods capable of achieving compression ratios as high as 100:1.

A robust-digital QRS-detection algorithm for arrhythmia monitoring.

The success of automated patient monitoring is primarily dependent on the ability to detect normal as well as bizarre QRS-complexes. In this paper a new robust single lead QRS-detection algorithm is presented. The QRS detector can be separated into five different blocks, namely, a noise filter, a differentiator, an energy collector, a minimal distance classifier, and a minimax trimmer. Each block accounts for some characteristic features of QRS complexes (steepness, duration, etc.). The time delay introduced by this algorithm for making a decision is less then one second, allowing real-time applications. The performance of the QRS detector is analyzed and results are presented.