1,721,012 research outputs found
Method and device for monitoring the risks for sudden infant death syndrom and for positional plagiocephaly
No full textA portable monitoring device (101) performs the monitoring of the short term, mid term and long term risks of Sudden Infant Death Syndrome (SIDS). It is also used to estimate the risk of onset of positional plagiocephaly. The monitoring device (101) is capable to acquire one or more signals associated to the typical breath and positioning patterns of an infant through a tri-axial accelerometer, and to register the data in electronic format. Statistical analysis of the signal and pattern recognition are performed in real time by a processing unit of the monitoring device. The monitoring device (101) can be used for monitoring the breath activity of an infant in various conditions, alerting a caregiver when a potentially dangerous situation is detected, with respect to a SIDS event or to the onset of plagiocephaly.; Thanks to its simplicity of use, small encumbrance and low power consumption, it can be turned on and attached to the clothes of the infant for as long as one day (or more), without the need of further supervision. Registered data can be transferred on a computer through a standard USB port, which can also be used for recharging a battery of the monitoring device (101). Statistical analysis of the registered data can be performed by a computer for quantifying the long term SIDS risk, the risk of plagiocephaly and for optimizing the functional parameters of the monitoring device (101). To get a more accurate estimation of the risk of plagiocephaly, the monitoring device (101) can be attached to the head of an infant
A New Real Time Filter for Local Exposure Correction in Panoramic Radiography
No full textA new real time filter for local exposure correction in panoramic radiographs is presented here. The filter, called PaRSEC, allows eliminating the exposure artifacts, mainly introduced by Automatic Exposure Control (AEC) systems. These artifacts reduce the image readability and its diagnostic utility. The PaRSEC filter operates a local exposure equalization, based on a reliable estimate of the column mean gray level. Qualitative and quantitative results are reported for typical panoramic radiographs. They show a complete removal of the artifacts. The method compares favorably with other classical methods targeted to exposure correctio
Real time enhancement of cephalometric radiographies
No full textWe present here a real time filtering procedure, called S.Ti.F., which is able to make both soft and bone tissue clearly visible into a cephalometric radiography. Histogram based clustering allows separating the bone pixels from the other ones. Different gamma corrections are then applied to bone and soft tissue areas, in order to obtain a clear visualization of the local anatomical structures. Trials on a large dataset of images demonstrated the power of the proposed filter. The real time processing and the possibility to interactively modify the filter parameters make it a very useful tool for dentists and surgeons
Real-time accurate circle fitting with occlusions
No full textAccurate location of circles inside images is a common problem in many scientific fields. Traditional algorithms, based on fitting a parameterized model, cannot accurately determine the circle in presence of partial occlusions. A novel problem formulation, based on maximum likelihood, allows estimating circles in real-time with sub-pixel accuracy also when occlusions are present
Compression and smart coding of offset ad gain maps for intraoral digital x-ray sensors
No full textThe response of indirect x-ray digital imaging sensors is often not homogenous on the entire surface area. In this case, calibration is needed to build offset and gain maps, which are used to correct the
sensor output. The sensors of new generation are equipped with an on-board memory, which serves to store these maps. However, because of its limited dimension, the maps have to be compressed before saving them. This step is critical because of the extremely high compression rate required.
The authors propose here a novel method to achieve such a high compression rate, without degrading the quality of the sensor output. It is based on quad tree decomposition, which performs an adaptive sampling of the offset and gain maps, matched with a RBF-based interpolation strategy.
The method was tested on a typical intraoral radiographic sensor and compared with traditional compression techniques. Qualitative and quantitative results show that the method achieves a higher
compression rate and produces images of superior quality. The method can be adopted also in different fields where a high compression rate is required
Soft Tissue Filtering
No full textA method is disclosed for enhancing the visibility of at least some features of a radiographic image, the features belonging to at least a first and a second category of features, the method including the steps of determining a histogram of the image, analyzing the histogram in order to determine a distinction between values of image elements that more likely show a feature of the first category and values of image elements that more likely show a feature of the second category, and applying a correction to at least some of the image elements, wherein an image element that, according to the determined distinction, more likely shows a feature of the first category is corrected differently than an image element that, according to the determined distinction, more likely shows a feature of the second category. An apparatus and a computer-readable data carrier are adapted for performing the above steps or for causing a processor to perform the above steps
Accelerometer-based correction of skewed horizon and keystone distortion in digital photography
No full textImproper camera orientation produces convergent vertical lines (keystone distortion) and skewed horizon lines (horizon distortion) in digital pictures; an a-posteriori processing is then necessary to obtain appealing pictures. We show here that, after accurate calibration, the camera on-board accelerometer can be used to automatically generate an alternative perspective view from a virtual camera, leading to images with residual keystone and horizon distortions that are essentially imperceptible at visual inspection. Furthermore, we describe the uncertainty on the position of each pixel in the corrected image with respect to the accelerometer noise. Experimental results show a similar accuracy for a smartphone and for a digital reflex camera. The method can find application in customer imaging devices as well as in the computer vision field, especially when reference vertical and horizontal features are not easily detectable in the image. © 2014 Elsevier B.V
Compact tracking of surgical instruments through structured markers
No full textVirtual and augmented reality surgery calls for reliable and efficient tracking of the surgical instruments in the virtual or real operating theatre. The most diffused approach uses three or more not aligned markers, attached to each instrument and surveyed by a set of cameras. However, the structure required to carry the markers does modify the instrument's mass distribution and can interfere with surgeon movements. To overcome these problems, we propose here a new methodology, based on structured markers, to compute the six degrees of freedom of a surgical instrument. Two markers are attached on the instrument axis and one of them has a stripe painted over its surface. We also introduce a procedure to compute with high accuracy the markers center on the cameras image, even when partially occluded by the instrument's axis or by other structures. Experimental results demonstrate the reliability and accuracy of the proposed approach. The introduction of structured passive markers can open new possibilities to accurate tracking, combining markers detection with real-time image processing
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