| Records |
| Author |
Aura Hernandez-Sabate |
| Title |
Automatic adventitia segmentation in IntraVascular UltraSound images |
Type |
Report |
| Year |
2005 |
Publication |
CVC Technical Report |
Abbreviated Journal |
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| Volume |
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Issue |
85 |
Pages |
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| Keywords |
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| Abstract |
A usual tool in cardiac disease diagnosis is vessel plaque assessment by analysis of IVUS sequences. Manual detection of lumen-intima, intima-media and media-adventitia vessel borders is the main activity of physicians in the process of plaque quantification. Large variety in vessel border descriptors, as well as, shades, artifacts and blurred response due to ultrasound physical properties troubles automated media-adventitia segmentation. This experimental work presents a solution to such a complex problem. The process blends advanced anisotropic filtering operators and statistic classification techniques, achieving an efficient vessel border modelling strategy. First of all, we introduce the theoretic base of the method. After that, we show the steps of the algorithm, validating the method with statistics that show that the media-adventitia border detection achieves an accuracy in the range of inter-observer variability regardless of plaque nature, vessel geometry and incomplete vessel borders. Finally, we present a little Matlab application to the automatic media-adventitia border. |
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Thesis |
Master's thesis |
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Place of Publication |
08193 Bellaterra, Barcelona (Spain) |
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IAM; |
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no |
| Call Number |
IAM @ iam @ Her2005 |
Serial |
1544 |
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| Author |
Aura Hernandez-Sabate; Debora Gil;Eduard Fernandez-Nofrerias;Petia Radeva; Enric Marti |
| Title |
Approaching Artery Rigid Dynamics in IVUS |
Type |
Journal Article |
| Year |
2009 |
Publication |
IEEE Transactions on Medical Imaging |
Abbreviated Journal |
TMI |
| Volume |
28 |
Issue |
11 |
Pages |
1670-1680 |
| Keywords |
Fourier analysis; intravascular ultrasound (IVUS) dynamics; longitudinal motion; quality measures; tissue deformation. |
| Abstract |
Tissue biomechanical properties (like strain and stress) are playing an increasing role in diagnosis and long-term treatment of intravascular coronary diseases. Their assessment strongly relies on estimation of vessel wall deformation. Since intravascular ultrasound (IVUS) sequences allow visualizing vessel morphology and reflect its dynamics, this technique represents a useful tool for evaluation of tissue mechanical properties. Image misalignment introduced by vessel-catheter motion is a major artifact for a proper tracking of tissue deformation. In this work, we focus on compensating and assessing IVUS rigid in-plane motion due to heart beating. Motion parameters are computed by considering both the vessel geometry and its appearance in the image. Continuum mechanics laws serve to introduce a novel score measuring motion reduction in in vivo sequences. Synthetic experiments validate the proposed score as measure of motion parameters accuracy; whereas results in in vivo pullbacks show the reliability of the presented methodologies in clinical cases. |
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Edition |
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| ISSN |
0278-0062 |
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IAM; MILAB |
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no |
| Call Number |
IAM @ iam @ HGF2009 |
Serial |
1545 |
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| Author |
Aura Hernandez-Sabate; Debora Gil; Jaume Garcia; Enric Marti |
| Title |
Image-based Cardiac Phase Retrieval in Intravascular Ultrasound Sequences |
Type |
Journal Article |
| Year |
2011 |
Publication |
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control |
Abbreviated Journal |
T-UFFC |
| Volume |
58 |
Issue |
1 |
Pages |
60-72 |
| Keywords |
3-D exploring; ECG; band-pass filter; cardiac motion; cardiac phase retrieval; coronary arteries; electrocardiogram signal; image intensity local mean evolution; image-based cardiac phase retrieval; in vivo pullbacks acquisition; intravascular ultrasound sequences; longitudinal motion; signal extrema; time 36 ms; band-pass filters; biomedical ultrasonics; cardiovascular system; electrocardiography; image motion analysis; image retrieval; image sequences; medical image processing; ultrasonic imaging |
| Abstract |
Longitudinal motion during in vivo pullbacks acquisition of intravascular ultrasound (IVUS) sequences is a major artifact for 3-D exploring of coronary arteries. Most current techniques are based on the electrocardiogram (ECG) signal to obtain a gated pullback without longitudinal motion by using specific hardware or the ECG signal itself. We present an image-based approach for cardiac phase retrieval from coronary IVUS sequences without an ECG signal. A signal reflecting cardiac motion is computed by exploring the image intensity local mean evolution. The signal is filtered by a band-pass filter centered at the main cardiac frequency. Phase is retrieved by computing signal extrema. The average frame processing time using our setup is 36 ms. Comparison to manually sampled sequences encourages a deeper study comparing them to ECG signals. |
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0885-3010 |
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| Notes |
IAM;ADAS |
Approved |
no |
| Call Number |
IAM @ iam @ HGG2011 |
Serial |
1546 |
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| Author |
Aura Hernandez-Sabate; Debora Gil; Petia Radeva |
| Title |
A Deterministic-Statistical Strategy for Adventitia Segmentation in IVUS images |
Type |
Report |
| Year |
2005 |
Publication |
CVC Technical Report |
Abbreviated Journal |
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| Volume |
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Issue |
89 |
Pages |
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| Keywords |
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| Abstract |
A useful tool for some specific studies in cardiac disease diagnosis is vessel plaque assessment by analysis of IVUS sequences. Manual detection of luminal (inner) and media-adventitia (external) vessel borders is the main activity of physicians in the process of lumen narrowing (plaque) quantification. Difficult definition of vessel border descriptors, as well as, shades, artifacts and blurred signal response due to ultrasound physical properties troubles automated adventitia segmentation. In order to efficiently approach such a complex problem, we propose blending advanced anisotropic filtering operators and statistical classification techniques into a vessel border modelling strategy. Our systematic statistical analysis shows that the reported adventitia detection achieves an accuracy in the range of inter-observer variability regardless of plaque nature, vessel geometry and incomplete vessel borders. |
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| Notes |
IAM; MILAB |
Approved |
no |
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IAM @ iam @ HGR2005a |
Serial |
1548 |
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| Author |
Aura Hernandez-Sabate; Debora Gil; Petia Radeva |
| Title |
On the usefulness of supervised learning for vessel border detection in IntraVascular Imaging |
Type |
Conference Article |
| Year |
2005 |
Publication |
Proceeding of the 2005 conference on Artificial Intelligence Research and Development |
Abbreviated Journal |
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| Volume |
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Issue |
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Pages |
67-74 |
| Keywords |
classification; vessel border modelling; IVUS |
| Abstract |
IntraVascular UltraSound (IVUS) imaging is a useful tool in diagnosis of cardiac diseases since sequences completely show the morphology of coronary vessels. Vessel borders detection, especially the external adventitia layer, plays a central role in morphological measures and, thus, their segmentation feeds development of medical imaging techniques. Deterministic approaches fail to yield optimal results due to the large amount of IVUS artifacts and vessel borders descriptors. We propose using classification techniques to learn the set of descriptors and parameters that best detect vessel borders. Statistical hypothesis test on the error between automated detections and manually traced borders by 4 experts show that our detections keep within inter-observer variability. |
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| Publisher |
IOS Press |
Place of Publication |
Amsterdam, The Netherlands |
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| Notes |
IAM;MILAB |
Approved |
no |
| Call Number |
IAM @ iam @ HGR2005c |
Serial |
1549 |
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| Author |
Aura Hernandez-Sabate; Debora Gil; Albert Teis |
| Title |
How Do Conservation Laws Define a Motion Suppression Score in In-Vivo Ivus Sequences? |
Type |
Conference Article |
| Year |
2007 |
Publication |
Proc. IEEE Ultrasonics Symp |
Abbreviated Journal |
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Issue |
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Pages |
2231-2234 |
| Keywords |
validation standards; IVUS motion compensation; conservation laws. |
| Abstract |
Evaluation of arterial tissue biomechanics for diagnosis and treatment of cardiovascular diseases is an active research field in the biomedical imaging processing area. IntraVascular UltraSound (IVUS) is a unique tool for such assessment since it reflects tissue morphology and deformation. A proper quantification and visualization of both properties is hindered by vessel structures misalignments introduced by cardiac dynamics. This has encouraged development of IVUS motion compensation techniques. However, there is a lack of an objective evaluation of motion reduction ensuring a reliable clinical application This work reports a novel score, the Conservation of Density Rate (CDR), for validation of motion compensation in in-vivo pullbacks. Synthetic experiments validate the proposed score as measure of motion parameters accuracy; while results in in vivo pullbacks show its reliability in clinical cases. |
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| Notes |
IAM |
Approved |
no |
| Call Number |
IAM @ iam @ HTG2007 |
Serial |
1550 |
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| Author |
Aura Hernandez-Sabate; Monica Mitiko; Sergio Shiguemi; Debora Gil |
| Title |
A validation protocol for assessing cardiac phase retrieval in IntraVascular UltraSound |
Type |
Conference Article |
| Year |
2010 |
Publication |
Computing in Cardiology |
Abbreviated Journal |
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| Volume |
37 |
Issue |
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Pages |
899-902 |
| Keywords |
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| Abstract |
A good reliable approach to cardiac triggering is of utmost importance in obtaining accurate quantitative results of atherosclerotic plaque burden from the analysis of IntraVascular UltraSound. Although, in the last years, there has been an increase in research of methods for retrospective gating, there is no general consensus in a validation protocol. Many methods are based on quality assessment of longitudinal cuts appearance and those reporting quantitative numbers do not follow a standard protocol. Such heterogeneity in validation protocols makes faithful comparison across methods a difficult task. We propose a validation protocol based on the variability of the retrieved cardiac phase and explore the capability of several quality measures for quantifying such variability. An ideal detector, suitable for its application in clinical practice, should produce stable phases. That is, it should always sample the same cardiac cycle fraction. In this context, one should measure the variability (variance) of a candidate sampling with respect a ground truth (reference) sampling, since the variance would indicate how spread we are aiming a target. In order to quantify the deviation between the sampling and the ground truth, we have considered two quality scores reported in the literature: signed distance to the closest reference sample and distance to the right of each reference sample. We have also considered the residuals of the regression line of reference against candidate sampling. The performance of the measures has been explored on a set of synthetic samplings covering different cardiac cycle fractions and variabilities. From our simulations, we conclude that the metrics related to distances are sensitive to the shift considered while the residuals are robust against fraction and variabilities as far as one can establish a pair-wise correspondence between candidate and reference. We will further investigate the impact of false positive and negative detections in experimental data. |
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IEEE |
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0276-6547 |
ISBN |
978-1-4244-7318-2 |
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Conference |
CINC |
| Notes |
IAM; |
Approved |
no |
| Call Number |
IAM @ iam @ HSM2010 |
Serial |
1551 |
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| Author |
Aura Hernandez-Sabate; Petia Radeva; Antonio Tovar; Debora Gil |
| Title |
Vessel structures alignment by spectral analysis of ivus sequences |
Type |
Conference Article |
| Year |
2006 |
Publication |
Proc. of CVII, MICCAI Workshop |
Abbreviated Journal |
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| Volume |
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Issue |
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Pages |
39-36 |
| Keywords |
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| Abstract |
Three-dimensional intravascular ultrasound (IVUS) allows to visualize and obtain volumetric measurements of coronary lesions through an exploration of the cross sections and longitudinal views of arteries. However, the visualization and subsequent morpho-geometric measurements in IVUS longitudinal cuts are subject to distortion caused by periodic image/vessel motion around the IVUS catheter. Usually, to overcome the image motion artifact ECG-gating and image-gated approaches are proposed, leading to slowing the pullback acquisition or disregarding part of IVUS data. In this paper, we argue that the image motion is due to 3-D vessel geometry as well as cardiac dynamics, and propose a dynamic model based on the tracking of an elliptical vessel approximation to recover the rigid transformation and align IVUS images without loosing any IVUS data. We report an extensive validation with synthetic simulated data and in vivo IVUS sequences of 30 patients achieving an average reduction of the image artifact of 97% in synthetic data and 79% in real-data. Our study shows that IVUS alignment improves longitudinal analysis of the IVUS data and is a necessary step towards accurate reconstruction and volumetric measurements of 3-D IVUS. |
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Copenhaguen (Denmark), |
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1st International Wokshop on Computer Vision for Intravascular and Intracardiac Imaging (CVII’06) |
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IAM; MILAB |
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no |
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IAM @ iam @ HRT2006 |
Serial |
1552 |
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| Author |
Aura Hernandez-Sabate; David Rotger; Debora Gil |
| Title |
Image-based ECG sampling of IVUS sequences |
Type |
Conference Article |
| Year |
2008 |
Publication |
Proc. IEEE Ultrasonics Symp. IUS 2008 |
Abbreviated Journal |
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Issue |
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Pages |
1330-1333 |
| Keywords |
Longitudinal Motion; Image-based ECG-gating; Fourier analysis |
| Abstract |
Longitudinal motion artifacts in IntraVascular UltraSound (IVUS) sequences hinders a properly 3D reconstruction and vessel measurements. Most of current techniques base on the ECG signal to obtain a gated pullback without the longitudinal artifact by using a specific hardware or the ECG signal itself. The potential of IVUS images processing for phase retrieval still remains little explored. In this paper, we present a fast forward image-based algorithm to approach ECG sampling. Inspired on the fact that maximum and minimum lumen areas are related to end-systole and end-diastole, our cardiac phase retrieval is based on the analysis of tissue density of mass along the sequence. The comparison between automatic and manual phase retrieval (0.07 ± 0.07 mm. of error) encourages a deep validation contrasting with ECG signals. |
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Beijing (China) |
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IAM;MILAB |
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no |
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IAM @ iam @ HRG2008 |
Serial |
1553 |
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| Author |
Aura Hernandez-Sabate; Debora Gil; Josefina Mauri; Petia Radeva |
| Title |
Reducing cardiac motion in IVUS sequences |
Type |
Conference Article |
| Year |
2006 |
Publication |
Proceeding of Computers in Cardiology |
Abbreviated Journal |
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| Volume |
33 |
Issue |
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Pages |
685-688 |
| Keywords |
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| Abstract |
Cardiac vessel displacement is a main artifact in IVUS sequences. It hinders visualization of the main structures in an appropriate orientation and alignment and affects extracting vessel measurements. In this paper, we present a novel approach for image sequence alignment based on spectral analysis, which removes rigid dynamics, preserving at the same time the vessel geometry. First, we suppress the translation by taking, for each frame, the center of mass of the image as origin of coordinates. In polar coordinates with such point as origin, the rotation appears as a horizontal displacement. The translation induces a phase shift in the Fourier coefficients of two consecutive polar images. We estimate the phase by adjusting a regression plane to the phases of the principal frequencies. Experiments show that the presented strategy suppress cardiac motion regardless of the acquisition device. 1. |
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IAM; MILAB |
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no |
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IAM @ iam @ HGM2006a |
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1554 |
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| Author |
Aura Hernandez-Sabate; Debora Gil; Petia Radeva; E.N.Nofrerias |
| Title |
Anisotropic processing of image structures for adventitia detection in intravascular ultrasound images |
Type |
Conference Article |
| Year |
2004 |
Publication |
Proc. Computers in Cardiology |
Abbreviated Journal |
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| Volume |
31 |
Issue |
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Pages |
229-232 |
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| Abstract |
The adventitia layer appears as a weak edge in IVUS images with a non-uniform grey level, which difficulties its detection. In order to enhance edges, we apply an anisotropic filter that homogenizes the grey level along the image significant structures (ridges, valleys and edges). A standard edge detector applied to the filtered image yields a set of candidate points prone to be unconnected. The final model is obtained by interpolating the former line segments along the tangent direction to the level curves of the filtered image with an anisotropic contour closing technique based on functional extension principles |
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Chicago (USA) |
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IAM; MILAB |
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no |
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IAM @ iam @ HGR2004 |
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1555 |
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| Author |
Ole Vilhelm-Larsen; Petia Radeva; Enric Marti |
| Title |
Guidelines for choosing optimal parameters of elasticity for snakes |
Type |
Book Chapter |
| Year |
1995 |
Publication |
Computer Analysis Of Images And Patterns |
Abbreviated Journal |
LNCS |
| Volume |
970 |
Issue |
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106-113 |
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| Abstract |
This paper proposes a guidance in the process of choosing and using the parameters of elasticity of a snake in order to obtain a precise segmentation. A new two step procedure is defined based on upper and lower bounds on the parameters. Formulas, by which these bounds can be calculated for real images where parts of the contour may be missing, are presented. Experiments on segmentation of bone structures in X-ray images have verified the usefulness of the new procedure. |
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Lecture Notes in Computer Science |
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LNCS |
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MILAB;IAM |
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no |
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IAM @ iam @ LRM1995b |
Serial |
1558 |
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Ole Larsen; Petia Radeva; Enric Marti |
| Title |
Bounds on the optimal elasticity parameters for a snake |
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Journal Article |
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1995 |
Publication |
Image Analysis and Processing |
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37-42 |
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This paper develops a formalism by which an estimate for the upper and lower bounds for the elasticity parameters for a snake can be obtained. Objects different in size and shape give rise to different bounds. The bounds can be obtained based on an analysis of the shape of the object of interest. Experiments on synthetic images show a good correlation between the estimated behaviour of the snake and the one actually observed. Experiments on real X-ray images show that the parameters for optimal segmentation lie within the estimated bounds. |
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MILAB;IAM |
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no |
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IAM @ iam @ LRM1995a |
Serial |
1559 |
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| Author |
Ole Larsen; Petia Radeva; Enric Marti |
| Title |
Calculating the Bounds on the Optimal Parameters of Elasticity for a Snake |
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Report |
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1994 |
Publication |
Technical Report |
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Aalborg University |
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Aalborg University, Laboratory of image Analysis. |
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Denmark |
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Aalborg University, Laboratory of image Analysis. |
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MILAB;IAM |
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no |
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IAM @ iam @ LRM1994 |
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1560 |
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| Author |
Josep Llados; Horst Bunke; Enric Marti |
| Title |
Finding rotational symmetries by cyclic string matching |
Type |
Journal Article |
| Year |
1997 |
Publication |
Pattern recognition letters |
Abbreviated Journal |
PRL |
| Volume |
18 |
Issue |
14 |
Pages |
1435-1442 |
| Keywords |
Rotational symmetry; Reflectional symmetry; String matching |
| Abstract |
Symmetry is an important shape feature. In this paper, a simple and fast method to detect perfect and distorted rotational symmetries of 2D objects is described. The boundary of a shape is polygonally approximated and represented as a string. Rotational symmetries are found by cyclic string matching between two identical copies of the shape string. The set of minimum cost edit sequences that transform the shape string to a cyclically shifted version of itself define the rotational symmetry and its order. Finally, a modification of the algorithm is proposed to detect reflectional symmetries. Some experimental results are presented to show the reliability of the proposed algorithm |
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Elsevier |
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Expedition |
|
Conference |
|
| Notes |
DAG;IAM; |
Approved |
no |
| Call Number |
IAM @ iam @ LBM1997a |
Serial |
1562 |
| Permanent link to this record |
