Search results for "Pixel"

Extract information of polarization imaging from local matching stereo

2010

Since polarization of light was used in the field of computer vision, the research of polarization vision is rapidly growing. Polarization vision has been shown to simplify some important image understanding tasks that can be more difficult to be performed with intensity vision. Furthermore, it has computational efficiency because it only needs grayscale images and can be easily applied by a simple optical setup. Nowadays, we can find various types of polarization cameras in the market. However, they are very expensive. In our work, we will study and develop a low price polarization camera setup with parallel acquisition using a stereo system. This system requires only two general cameras e…

Choosing local matching score method for stereo matching based-on polarization imaging

2010

Polarization imaging is a powerful tool to observe hidden information from an observed object. It has significant advantages, such as computational efficiency (it only needs gray scale images) and can be easily applied by adding a polarizer in front of a camera. Many researchers used polarization in various areas of computer vision, such as object recognition, segmentation and so on. However, there is very little research in stereo vision based on polarization. Stereo vision is a well known technique for obtaining depth information from pairs of stereo digital images. One of the main focuses of research in this area is to get accurate stereo correspondences. In our work, we will study and d…

Subsecond fluorine-19 MRI of the lung

2006

Minimal scan times in rapid fluorine-19 MRI using sulfur hexafluoride (SF6) have been on the order of 10 s. Because of the very short T1 relaxation time of SF6 (T1 = 1.65 ms), high receiver bandwidths are necessary to allow for a high number of excitations. Since high bandwidths cause high levels of electronic noise, SNR per acquisition has been too low to further reduce scan time. The purpose of this study was to investigate whether scan times could be reduced using hexafluoroethane (C2F6), a gas with a longer T1 (T1 = 7.9 ms) at a relatively low bandwidth of 488 Hz/pixel. Gradient-echo images were acquired during and after completion of the wash-in of a 70% C2F6- 30% O2 mixture. Peak SNR …

Estimating intrinsic image from successive images by solving underdetermined and overdetermined systems of the dichromatic model

2020

International audience; Estimating an intrinsic image from a sequence of successive images taken from an object at different angles of illumination can be used in various applications such as objects recognition, color classification, and the like; because, in so doing, it can provide more visual information. Meanwhile, according to the well-known dichromatic model, each image can be considered a linear combination of three components, including intrinsic image, shading factor, and specularity. In this study, at first, two simple independent constrained and parallelized quadratic programming steps were used for computing values of the shading factor and the specularity of each successive of…

Adapted processing of catadioptric images using polarization imaging

2009

A non parametric method that defines a pixel neighborhood within catadioptric images is presented in this paper. It is based on an accurate modeling of the mirror shape by using polarization imaging. Unlike the most of current processing methods in the literature, this method is non-parametric and can deal with the deformation of catadioptric images. This paper demonstrates how an appropriate neighborhood can be derived from the polarization parameters by estimation of the degree of polarization and the angle of polarization which in return directly provide an adapted neighborhood of each pixel that can be used to perform image derivation, edge detection, interest point detection and namely…

A new angle on contour integration: The role of corners

2017

Accuracy of stereotactic coordinate transformation using a localisation frame and computed tomographic imaging

1999

The accuracy of coordinate transformation from the computed tomographic (CT) space to the stereotactic frame space was analysed for frame-based stereotactic systems which use a localisation frame and coordinate transformation based on matrix calculation. The coordinate transformation was divided into three consecutive steps: (1) transforming the localisation frame into the CT image built up from pixels with distinct attenuation values, (2) determining the rod centres of the localisation frame in the CT image, and (3) coordinate transformation from the image to the frame space using the centres of the rods in the image space and algebraic, matrix-based calculation. The error contribution at …

<title>Spectral/spatial integration effects on information extraction from multispectral data: multiresolution approaches</title>

1995

New techniques for information extraction from multispectral data require physical modeling to understand the energy transfer at the atmosphere/surface interface and to develop appropriate inversion procedures, in combination with advanced processing techniques. A multi-step procedure is proposed in this work: the first step implies a binary decision about the second step to be applied in each case. If the pixel is considered as being a `pure' pixel, through a spectral/spatial classification procedure based on multiresolution techniques, then numerical inversion techniques, based on a multiple-scattering reflectance model, are used to extract parameters representing specific surface propert…

Image Colorization Method Using Texture Descriptors and ISLIC Segmentation

2017

We present a new colorization method to assign color to a grayscale image based on a reference color image using texture descriptors and Improved Simple Linear Iterative Clustering (ISLIC). Firstly, the pixels of images are classified using Support Vector Machine (SVM) according to texture descriptors, mean luminance, entropy, homogeneity, correlation, and local binary pattern (LBP) features. Then, the grayscale image and the color image are segmented into superpixels, which are obtained by ISLIC to produce more uniform and regularly shaped superpixels than those obtained by SLIC, and the classified images are further post-processed combined with superpixles for removing erroneous classific…

Human Figure Recognition and the Estimation of its Direction

2006

This work describes a method used to recognize a person situated in indoor environments. It estimates the direction in which the person is turned. The position coordinates are known to the system thanks to localization techniques that use Bluetooth technology. The utilization of such information in intelligent environments allows the execution of actions that interact with the customer. The paper focuses on our human figure recognition technique, which uses image analysis to calculate the direction angle a person is turned towards. Figure recognition is accomplished by comparing the colours of the body parts that mark it out, such as: hair colour, face colour, and clothes colour. The calcul…