Jorge Rodriguez-Asomoza

Wavelet-based smoke detection in outdoor video sequences

In this paper an approach to detect smoke columns from outdoor forest video sequences is proposed. The approach follows three basic steps. The first step is an image pre-processing block which resizes the image by applying a bicubic interpolation algorithm. The image is then transformed to its intensity values with a gray-scale transformation and finally the image is grouped by common areas with an image indexation. The second step consists of a smoke detection algorithm which performs a stationary wavelet transform (SWT) to remove high frequencies on horizontal, vertical, and diagonal details. The inverse SWT is then implemented and finally the image is compared to a non-smoke scene in order to determine the possible regions of interest (ROI). In order to reduce the number of false alarms, the final step of the proposed approach consists on a smoke verification algorithm, which determines whether the ROI is increasing its area or not. These results are combined to reach a final decision for detecting a smoke column on a sequence of static images from an outdoor video. Experimental results show that multi-resolution wavelet analysis is more accurate than the traditional low-pass filters on this application.

Automated measurement of optical coherence lengths and optical delays for applications in coherence-modulated optical transmissions

The implementation of an automated system for analysis of coherence length of light and for the measurement of optical delays is reported. This type of measurement is very important for designing coherence-modulated optical transmission systems. Such systems have been studied for the last few years as new potential high-speed optical links useful for point-to-point, local area networks, and bidirectional transmissions, at optical wavelengths around 1300 nm. The main characteristics of coherence-modulated transmissions include the need of using low-coherence optical sources and integrated optics lithium niobate (LiNbO/sub 3/) electro-optic retarders. This paper describes the implementation of an automated system allowing the measurement of coherence lengths of semiconductor optical sources and also optical delays as essential data for designing coherence-modulated optical links. The reported results include characterization of commercial low-coherence semiconductor optical sources and integrated optics coherence modulators.

Electric field sensing system using coherence modulation of light

This paper describes an experimental setup for detecting electric fields using electrooptic lithium niobate (LiNbO/sub 3/) sensors and coherence modulation of light. In this detection scheme, the sensed electric fields modulate optical delays, which are introduced by LiNbO/sub 3/ coherence modulators when associated to low-coherence optical sources. The optical delays act as coherence-multiplexed carriers of the sensed electric fields and are transmitted through an optical fiber channel. At the receiver, the electric fields are detected by measuring the auto-correlation of the received light by using two-wave interferometers, which are matched to the introduced optical delays on the sensing devices.

Experimental transmission in a fiber-radio system using a microwave photonic filter at 2.8GHz

This paper deals with the experimental transmission of analog TV-signal in a fiber-radio scheme using a microwave photonic filter. For that purpose, filtering of a microwave band-pass window located at 2.8 GHz is obtained by the interaction of an externally modulated multimode laser diode emitting at 1.5μm associated to the chromatic dispersion parameter of an optical fiber. Transmission of TVsignal coded on the microwave band-pass window is achieved over an optical link of 20.70 Km. Demodulated signal is transmitted via radiofrequency using printed antennas. This communication scheme has a potential application in the field of FTTx network architectures.

Modeling and performance analysis of an all-optical photonic microwave filter in the frequency range of 0.01-15 GHz

The generation, distribution and processing of microwave signals in the optical domain is a topic of research due to many advantages such as low loss, light weight, broadband width, and immunity to electromagnetic interference. In this sense, a novel all-optical microwave photonic filter scheme is proposed and experimentally demonstrated in the frequency range of 0.01-15.0 GHz. A microwave signal generated by optical mixing drives the microwave photonic filter. Basically, photonic filter is composed by a multimode laser diode, an integrated Mach- Zehnder intensity modulator, and 28.3-Km of single-mode standard fiber. Frequency response of the microwave photonic filter depends of the emission spectral characteristics of the multimode laser diode, the physical length of the single-mode standard fiber, and the chromatic dispersion factor associated to this type of fiber. Frequency response of the photonic filter is composed of a low-pass band centered at zero frequency, and several band-pass lobes located periodically on the microwave frequency range. Experimental results are compared by means of numerical simulations in Matlab exhibiting a small deviation in the frequency range of 0.01-5.0 GHz. However, this deviation is more evident when higher frequencies are reached. In this paper, we evaluate the causes of this deviation in the range of 5.0-15.0 GHz analyzing the parameters involved in the frequency response. This analysis permits to improve the performance of the photonic microwave filter to higher frequencies.

Method to transmit analog information by using a long distance photonic link with distributed feedback lasers biased in the low laser threshold current region

We describe an analog microwave photonic link system, which is used to transmit in a multiplexed way a TV signal over 30 km of standard optical fiber. The experimental setup is composed mainly by two distributed feedback (DFB) laser diodes emitting at 1500 nm. When these DFB lasers are operated in the low laser threshold current region, relaxation oscillation frequencies are obtained. Relaxation oscillations in the laser intensity can be seen as sidebands on both sides of the main laser line. The optical emissions generated in each laser are combined and amplified by using an erbium-doped fiber amplifier. Next, the amplified optical signal is detected by a fast photo-detector using direct detection method, and as result of this photo-detection, microwave signals are generated. Since microwave signals obtained by using this technique are tuned continuously; we can use them as electrical carriers to transmit simultaneously a TV signal at 4 and 5 GHz and over 30 km of standard optical fiber by using a Mach-Zehnder modulator. At the end of the optical link the modulated light is photo-detected in order to recover efficiently and successfully the analog TV signal.

Automatic Image Annotation for Description of Urban and Outdoor Scenes

In this paper we present a novel approach for automatic annotation of objects or regions in images based on their color and texture. According to the proposed generalized architecture for automatic generation of image content descriptions the detected regions are labeled by developed cascade SVM-based classifier mapping them to structure that reflects their hierarchical and spatial relation used by text generation engine. For testing the designed system for automatic image annotation around 2,000 images with outdoor-indoor scenes from standard IAPR-TC12 image dataset have been processed obtaining an average precision of classification about 75 % with 94 % of recall. The precision of classification based on color features has been improved up to 15 ± 5 % after extension of classifier with texture detector based on Gabor filter. The proposed approach has a good compromise between classification precision of regions in images and speed despite used considerable time processing taking up to 1 s per image. The approach may be used as a tool for efficient automatic image understanding and description.

Shape Indexing and Retrieval: A Hybrid Approach Using Ontological Descriptions

This paper presents a novel hybrid approach for visual information retrieval (VIR) that combines shape analysis of objects in image with their indexing by textual descriptions. The principal goal of presented technique is applying Two Segments Turning Function (2STF) proposed by authors for efficient invariant to spatial variations shape processing and implementation of semantic Web approaches for ontology-based user-oriented annotations of multimedia information. In the proposed approach the user’s textual queries are converted to image features, which are used for images searching, indexing, interpretation, and retrieval. A decision about similarity between retrieved image and user’s query is taken computing the shape convergence to 2STF combining it with matching the ontological annotations of objects in image and providing in this way automatic definition of the machine-understandable semantics. In order to evaluate the proposed approach the Image Retrieval by Ontological Description of Shapes system has been designed and tested using some standard image domains.

A New Method for Designing Flat Shelving and Peaking Filters Based on Allpass Filters

Two most commonly IIR filters used in audio equalization are shelving filters and peaking filters. Traditional design of shelving and peaking filters is based on the design of analog filters, mainly Butterworth filters, and bilinear transformation. In this way, it is well known the design of first order shelving filters and second order peaking filters. Additionally, the resulting filter can be efficiently implemented using allpass filter structures with a low sensitivity to the filter quantization and a low noise level. In this paper, we present a direct design of high order shelving and peaking filters with flat magnitude response in both passband and stop-band. The design is reduced to the design of one digital allpass filter with real coefficients. Using this allpass filter, we obtain two stable and real allpass filters, which are used to implement the resulting shelving and peaking filters. Additionally, closed form equations for the pole/zero computations are given. In contrast with others proposed methods, the design parameters for the shelving filter are the gains KBdB and KcdB at omega=0 and omega=pi, respectively, the passband droop Ap, stopband attenuation As, passband frequency omegap, and stopband frequency omega s, while for the peaking filter we have the gains KBdB and KcdB, the passband and stopband attenuation Ap and As, passband width Wp, stopband width Ws, and the central frequency omega0. The proposed method is illustrated by means of examples. Finally, the appendix shows the MATLAB function ShelvingEq.m, which implements the proposed method for the design of shelving filters

Automated system for measuring optical parameters for coherence-modulated optical links

A computer-controlled system allowing automated measurements of coherence lengths and optical delays as starting data for designing coherence modulated optical links is described here. Modulation using optical delays as information carriers is currently known as coherence modulation. Main characteristics of coherence modulated transmissions include the need of using low-coherence optical sources and integrated optics retarders. The reported results include characterization of low-coherence semiconductor optical sources and lithium niobate (LiNbO3) integrated optics coherence modulators.