General nonparametric ROC curve comparison

Martinez-Camblor, Pablo,Carleos, Carlos,Corral, Norberto 한국통계학회 2013 Journal of the Korean Statistical Society Vol.42 No.1

Although the equality among two or more ROC (receiver operating characteristic) curves is usually contrasted from the respective AUCs (area under the ROC curve), two different ROC curves can share the same AUC and, in order to compare the ROC curves equality, most general criteria must be considered. In this paper, the authors deal with the general ROC curve comparison problem on paired design. They extend the tests for the classical cumulative distribution functions (CDF) comparison to the ROC curves context. To approximate the statistic distribution, two different resampling plans are considered; the usual one based on permutations and a new bootstrap procedure which does not require the exchangeability assumption. As usual, from Monte Carlo simulations, the performance of the proposed methodology is studied for two traditional tests; one based on the Kolmogorov-Smirnov criteria and the other one on the $L_2$-measure. The observed results suggest that the proposed bootstrap provides a good statistic distribution approximation for medium sample size. Therefore the studied methodology allows us to compare the equality of ROC curves by defining a criteria according to the needs of the problem.

Shaded-Mask Filtering for Extended Depth-of-Field Microscopy

Escobar, Isabel,Saavedra, Genaro,Martinez-Corral, Manuel,Calatayud, Arnau,Doblas, Ana The Korea Institute of Information and Commucation 2013 Journal of information and communication convergen Vol.11 No.2

This paper proposes a new spatial filtering approach for increasing the depth-of-field (DOF) of imaging systems, which is very useful for obtaining sharp images for a wide range of axial positions of the object. Many different techniques have been reported to increase the depth of field. However the main advantage in our method is its simplicity, since we propose the use of purely absorbing beam-shaping elements, which allows a high focal depth with a minimum modification of the optical architecture. In the filter design, we have used the analogy between the axial behavior of a system with spherical aberration and the transverse impulse response of a 1D defocused system. This allowed us the design of a ring-shaded filter. Finally, experimental verification of the theoretical statements is also provided.

Depth-of-Field Enhancement in Integral Imaging by Selective Depth-Deconvolution

Navarro, Hector,Saavedra, Genaro,Martinez-Corral, Manuel,Sjostrom, Marten,Olsson, Roger IEEE 2014 Journal of display technology Vol.10 No.3

<P>One of the major drawbacks of the integral imaging technique is its limited depth of field. Such limitation is imposed by the numerical aperture of the microlenses. In this paper, we propose a method to extend the depth of field of integral imaging systems in the reconstruction stage. The method is based on the combination of deconvolution tools and depth filtering of each elemental image using disparity map information. We demonstrate our proposal presenting digital reconstructions of a 3-D scene focused at different depths with extended depth of field.</P>

Computational volumetric reconstruction of integral imaging with improved depth resolution considering continuously non-uniform shifting pixels

Cho, Byungwoo,Kopycki, Przemyslaw,Martinez-Corral, Manuel,Cho, Myungjin Elsevier 2018 Optics and lasers in engineering Vol.111 No.-

<P><B>Abstract</B></P> <P>In this paper, we propose a new computational volumetric reconstruction technique of three-dimensional (3D) integral imaging for depth resolution enhancement by using non-uniform and integer-valued shifting pixels. In a typical integral imaging system, 3D images can be recorded and visualized using a lenslet array. In previous studies, many computational reconstruction techniques such as computational volumetric reconstruction and pixel of elemental images rearrangement technique (PERT) have been reported. However, a computational volumetric reconstruction technique has low visual quality and depth resolution because low-resolution elemental images and uniformly distributed shifting pixels are used for reconstruction. Although PERT can enhanced the visual quality of the 3D images, the size of the reconstructed 3D images is different from the original scene. On the other hand, our proposed method uses non-uniformly distributed shifting pixels for reconstruction instead of uniformly distributed shifting pixels. Therefore, the visual quality and depth resolution may be enhanced. Finally, our experimental results show the improvement of depth resolution and visual quality of the reconstructed 3D images.</P> <P><B>Highlights </B></P> <P> <UL> <LI> We present a new reconstruction of integral imaging with integer-valued and non-uniform shifting pixels as shown in Fig. 1. </LI> <LI> However, a conventional computational volumetric reconstruction has high reconstruction error and low depth resolution. </LI> <LI> Furthermore, if the resolution of the elemental images is low, these problems become even bigger. </LI> <LI> We proposed a reconstruction technique to improve depth resolution by using continuously non-uniform shifting pixels. </LI> <LI> Finally, our experimental results as shown in Fig. 2 show the improved depth resolution and reduced reconstruction errors. </LI> </UL> </P>

Transvaginal/transrectal ultrasound for assessing myometrial invasion in endometrial cancer: a comparison of six different approaches

Juan Luis Alcazar,Laura Pineda,Txanton Martinez-Astorquiza Corral,Rodrigo Orozco,Jesús Utrilla-Layna,Leire Juez,Matías Jurado 대한부인종양학회 2015 Journal of Gynecologic Oncology Vol.26 No.3

Objective: To compare the diagnostic performance of six different approaches for assessing myometrial infiltration using ultrasound in women with carcinoma of the corpus uteri. Methods: Myometrial infiltration was assessed by two-dimensional (2D) transvaginal or transrectal ultrasound in 169 consecutive women with well (G1) or moderately (G2) differentiated endometrioid type endometrial carcinoma. In 74 of these women three-dimensional (3D) ultrasound was also performed. Six different techniques for myometrial infiltration assessment were evaluated. The impression of examiner and Karlsson’s criteria were assessed prospectively. Endometrial thickness, tumor/ uterine 3D volume ratio, tumor distance to myometrial serosa (TDS), and van Holsbeke’s subjective model were assessed retrospectively. All subjects underwent surgical staging within 1 week after ultrasound evaluation. Definitive histopathological data regarding myometrial infiltration was used as gold standard. Sensitivity and specificity for all approaches were calculated and compared using McNemar test. Results: The impression of examiner and subjective model performed similarly (sensitivity 79.5% and 80.5%, respectively; specificity 89.6% and 90.3%, respectively). Both methods had significantly better sensitivity than Karlsson's criteria (sensitivity 31.8%, p<0.05) and endometrial thickness (sensitivity 47.7%, p<0.05), and better specificity than tumor/uterine volume ratio (specificity 28.3%, p<0.05) and TDS (specificity 41.5%, p<0.05). Conclusion: Subjective impression seems to be the best approach for assessing myometrial infiltration in G1 or G2 endometrioid type endometrial cancer by transvaginal or transrectal ultrasound. The use of mathematical models and other objective 2D and 3D measurement techniques do not improve diagnostic performance.

Three-Dimensional Imaging and Display through Integral Photography

Navarro, Hector,Dorado, Adrian,Saavedra, Genaro,Corral, Manuel Martinez The Korea Institute of Information and Commucation 2014 Journal of information and communication convergen Vol.12 No.2

Here, we present a review of the proposals and advances in the field of three-dimensional (3D) imaging acquisition and display made in the last century. The most popular techniques are based on the concept of stereoscopy. However, stereoscopy does not provide real 3D experience, and produces discomfort due to the conflict between convergence and accommodation. For this reason, we focus this paper on integral imaging, which is a technique that permits the codification of 3D information in an array of 2D images obtained from different perspectives. When this array of elemental images is placed in front of an array of microlenses, the perspectives are integrated producing 3D images with full parallax and free of the convergence-accommodation conflict. In the paper we describe the principles of this technique, together with some new applications of integral imaging.

Integral Imaging Monitors with an Enlarged Viewing Angle

Dorado, Adria,Saavedra, Genaro,Sola-Pikabea, Jorge,Martinez-Corral, Manuel The Korea Institute of Information and Commucation 2015 Journal of information and communication convergen Vol.13 No.2

Enlarging the horizontal viewing angle is an important feature of integral imaging monitors. Thus far, the horizontal viewing angle has been enlarged in different ways, such as by changing the size of the elemental images or by tilting the lens array in the capture and reconstruction stages. However, these methods are limited by the microlenses used in the capture stage and by the fact that the images obtained cannot be easily projected into different displays. In this study, we upgrade our previously reported method, called SPOC 2.0. In particular, our new approach, which can be called SPOC 2.1, enlarges the viewing angle by increasing the density of the elemental images in the horizontal direction and by an appropriate application of our transformation and reshape algorithm. To illustrate our approach, we have calculated some high-viewing angle elemental images and displayed them on an integral imaging monitor.

GPU-accelerated integral imaging and full-parallax 3D display using stereo–plenoptic camera system

Hong, Seokmin,Incardona, Nicolò,Inoue, Kotaro,Cho, Myungjin,Saavedra, Genaro,Martinez-Corral, Manuel Elsevier 2019 Optics and lasers in engineering Vol.115 No.-

<P><B>Abstract</B></P> <P>In this paper, we propose a novel approach to produce integral images ready to be displayed onto an integral-imaging monitor. Our main contribution is the use of commercial plenoptic camera, which is arranged in a stereo configuration. Our proposed set-up is able to record the radiance, spatial and angular, information simultaneously in each different stereo position. We illustrate our contribution by composing the point cloud from a pair of captured plenoptic images, and generate an integral image from the properly registered 3D information. We have exploited the graphics processing unit (GPU) acceleration in order to enhance the integral-image computation speed and efficiency. We present our approach with imaging experiments that demonstrate the improved quality of integral image. After the projection of such integral image onto the proposed monitor, 3D scenes are displayed with full-parallax.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The use of a stereo–plenoptic camera system. </LI> <LI> Novel for the composing sub-aperture image array from captured plenoptic image and calculate dense depth map. </LI> <LI> Compose a point cloud and registration between a pair of 3D data. </LI> <LI> Generate 3D image (integral image) from composed voxel in virtual 3D space. </LI> <LI> Display 3D images into integral imaging monitor with great parallax and viewing angle. </LI> </UL> </P>

Towards 3D Television Through Fusion of Kinect and Integral-Imaging Concepts

Seokmin Hong,Donghak Shin,Byung-Gook Lee,Dorado, Adrian,Saavedra, Genaro,Martinez-Corral, Manuel IEEE 2015 Journal of display technology Vol.11 No.11

<P>We report a new procedure for the capture and processing of light proceeding from 3D scenes of some cubic meters in size. Specifically we demonstrate that with the information provided by a kinect device it is possible to generate an array of microimages ready for their projection onto an integral-imaging monitor. We illustrate our proposal with some imaging experiment in which the final result are 3D images displayed with full parallax.</P>