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Publicações

Publicações por CTM

2008

<title>Automatic image registration based on correlation and Hough transform</title>

Autores
Gonçalves, H; Gonçalves, JA; Corte-Real, L;

Publicação
Image and Signal Processing for Remote Sensing XIV

Abstract

2008

A novel approach to joint video coding

Autores
Teixeira, L; Corte Real, L;

Publicação
IET Conference Publications

Abstract
It is expected that future delivery of digital TV signals will use H.264. This paper presents a novel coding scheme for multi-program video transmission in which the channel capacity is distributed among the programs according to the program complexities resulting in a more uniform overall image quality. A complexity bit rate control algorithm based on the structural similarity index (SSIM) is proposed. SSIM metric is presented under the hypothesis that the human visual system (HSV) is very specialized in extracting structural information from a video sequence but not in extracting the errors. Thus, a measurement on structural distortion should give a better correlation to the subjective impression. Computer simulations have demonstrated very promising results showing joint coding is able to effectively control the complexity of the multi-program encoding process whilst improving overall subjective compared to independent coding and algorithms based on traditional distortion/quality metrics. ©2008 The Institution of Engineering and Technology.

2008

Joint Coding of Multiple H.264 Video Programs

Autores
Teixeira, L; Corte Real, L;

Publicação
PROGRESS IN PATTERN RECOGNITION, IMAGE ANALYSIS AND APPLICATIONS, PROCEEDINGS

Abstract
This paper presents a joint coding scheme for multiple H.264/AVC video programs. Channel bandwidth is divided among different programs according its complexity. Several complexity metrics are assessed. Initial results are presented and discussed.

2008

Building modular surveillance systems based on multiple sources of information - Architecture and requirements

Autores
Duraes, D; Teixeira, LF; Corte Real, L;

Publicação
SIGMAP 2008: PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON SIGNAL PROCESSING AND MULTIMEDIA APPLICATIONS

Abstract
Intelligent surveillance is becoming increasingly important for the enhanced protection of facilities such as airports and power stations from various types of threats. We propose a surveillance system architecture based on multiple sources of information to apply on large scale surveillance networks. The main contribution of this paper is the definition of the requirements for a flexible and scalable architecture that supports intelligent surveillance using, alongside video, different sources of information, such as audio or other sensors.

2008

Automatic image registration based on correlation and Hough transform

Autores
Goncalves, H; Goncalves, JA; Corte Real, L;

Publicação
Proceedings of SPIE - The International Society for Optical Engineering

Abstract
Automatic image registration is a process related to various application fields such as remote sensing, medicine, computer vision, among others. Particularly in remote sensing, the ever increasing number of available satellite images asks for automatic image registration methods, capable of correctly align a new image. An automatic image registration method is proposed, based on the identification of a thin line through the Hough transform, from the diagonal brighter strip visible on the correlation images. This procedure is applied for both directions. Dividing an image into tiles and taking the center of each tile as a point, a geometric correction at the subpixel level may be achieved. Measures for an objective assessment of the geometric correction quality are also proposed, as a complement to the traditional RMS of the errors and visual inspection. An orthorectified Landsat image and an ASTER image with an approximate geometric correction were used. The images were superimposed and resampled. An image registration with subpixel accuracy was achieved. The proposed methodology has showed to be able to correctly align two images, having a priori a "gold standard" image covering a considerable part of the image to be registered. © 2008 SPIE.

2008

EBG PIFA Design for WLAN Applications

Autores
Luo, Q; Salgado, HM; Pereira, JR;

Publicação
2008 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM, VOLS 1-9

Abstract
This paper proposes a new low profile dual band WLAN Planar inverted-F antenna (PIFA) by using Electromagnetic Band-Gap (EBG) material as ground plane. The total thickness of this antenna is only 4 mm, which is half of the height when a normal perfect electric conductor (PEC) ground plane is used. The backward radiation ratio is also reduced as the existence of EBG. Moreover, the bandwidth for the 5 GHz; band is increased by 10 times compared to the reference antenna. This EBG PIFA is built on the ground plane with size of 40x62 mm, which is suitable for most of the mobile devices.

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