Otoniel López

Monitoring Pest Insect Traps by Means of Low-Power Image Sensor Technologies

Monitoring pest insect populations is currently a key issue in agriculture and forestry protection. At the farm level, human operators typically must perform periodical surveys of the traps disseminated through the field. This is a labor-, time- and cost-consuming activity, in particular for large plantations or large forestry areas, so it would be of great advantage to have an affordable system capable of doing this task automatically in an accurate and a more efficient way. This paper proposes an autonomous monitoring system based on a low-cost image sensor that it is able to capture and send images of the trap contents to a remote control station with the periodicity demanded by the trapping application. Our autonomous monitoring system will be able to cover large areas with very low energy consumption. This issue would be the main key point in our study; since the operational live of the overall monitoring system should be extended to months of continuous operation without any kind of maintenance (i.e., battery replacement). The images delivered by image sensors would be time-stamped and processed in the control station to get the number of individuals found at each trap. All the information would be conveniently stored at the control station, and accessible via Internet by means of available network services at control station (WiFi, WiMax, 3G/4G, etc.).

A Study of Objective Quality Assessment Metrics for Video Codec Design and Evaluation

When comparing the performance of different video coding approaches, improvements or new codec designs, one of the most important performance metrics is the rate/distortion (R/D), where distortion use to be measured in terms of PSNR (peak signal-to-noise ratio) values. However, it is well known that this metric not always capture the distortion perceived by the human being. So, a lot efforts were performed to define an objective video quality metric that is able to measure video quality distortion close to the one perceived for the destination user. In this work, we perform a study of different available objective quality metrics in order to evaluate their behaviour, taking as reference the classical PSNR metric. Our purpose is to find, if any, a video quality metric that is able to substitute PSNR for video quality assessment and determine a more accurate R/D performance metric when designing and evaluating video codec proposals

Quality assessment metrics vs. PSNR under packet lossscenarios in manet wireless networks

It is well known that PSNR does not always rank quality of an image or video sequence in the same way that a human being. There are many other factors considered by the human visual system and the brain. So, a lot of efforts were required to find an objective video quality metric that is able to measure the quality distortion similarly to the one perceived by the destination user. We analyze the behaviour of some of the most relevant objective quality metrics when they are applied to video compressed by a H264/AVC codec at different bit-rates and with error resilience options enabled. Video data is transmitted in a wireless MANET environment and packet losses are modelled for different scenarios including variable congestion and mobility states. We take as reference the PSNR metric and try to find out if there is a more accurate metric in terms of human quality perception that could substitute PSNR in the performance evaluation of different coding proposals under packet loss scenarios.

Modeling video streaming over VANETs

Transmitting video over Vehicular Adhoc NETworks (VANETs) is a hard-to-manage task. This is due to VANET problems (attenuation, packet losses, changing topology, etc.) and video streaming high requirements. To find out the feasibility of video streaming over VANETs and which error resilience strategies can improve video quality, testing is necessary. A real test with hundreds of vehicles communicating to each other is not an easy to get benchmark. So, modeling vehicular networks is mandatory to predict the behavior of video streaming applications and evaluate the feasibility of deploying vehicular video services. In this paper we present a set of available software tools for VANETs and video streaming modeling. A complete experiment is drawn from scratch to illustrate the usage of these tools.

E-LTW: An enhanced LTW encoder with sign coding and precise rate control

Traditional embedded coding systems involve high complexity algorithms, requiring fast and expensive processors. In the last years, several authors have developed very fast and simple non-embedded wavelet encoders that are able to get reasonable good performance with reduced computing requirements. These encoders have lost the SNR scalability and precise rate control capabilities. In this paper, we propose a new non-embedded LTW codec version (E-LTW) with precise rate control method and good R/D performance due to the use of intra band neighboring context modeling for sign coding.

Impact of rate control tools on very fast non-embedded wavelet image encoders

Recently, there has been an increasing interest in the design of very fast wavelet image encoders focused on applications (interactive real-time image&video applications, GIS systems, etc) and devices (digital cameras, mobile phones, PDAs, etc) where coding delay and/or available computing resources (working memory and power processing) are critical for proper operation. Most of these fast wavelet image encoders are non-embedded in order to reduce complexity, so no rate control tools are available for scalable coding applications. In this work, we analyze the impact of simple rate control tools for these encoders in order to determine if the inclusion of rate control functionality is worth enough with respect to popular embedded encoders like SPIHT and JPEG2000. We perform the study by adding rate control to the nonembedded LTW encoder, showing that the increase in complexity still maintains LTW competitive with respect SPIHT and JPEG2000 in terms of R/D performance, coding delay and memory consumption.

M-LTW: A fast and efficient intra video codec

Intra-video coding is a common way to process video material for applications like professional video editing systems, digital cinema, video surveillance applications, multi-spectral satellite imaging, HQ video delivery, etc. Most practical intra-coding systems employ JPEG encoders due to their simplicity, low coding delay and low memory requirements. JPEG2000 is the main candidate to replace JPEG in this kind of application due to its excellent rate/distortion (R/D) performance and high coding flexibility. However, its complexity and computational resource requirements for proper operation could be a limitation for certain applications. In this work, we propose an intra-video codec, M-LTW, which is able to obtain very good R/D performance results, as good as JPEG2000 or H.264 INTRA, with faster processing and lower memory usage.

Evaluating HEVC video delivery in VANET scenarios

Video delivery over VANETs is a difficult task. On the one hand, video streaming is a demanding application, where big deals of data need to be processed and transmitted. On the other hand, VANETs are error prone networks due to the high mobility of the nodes and the wireless channel. The sum of these two factors makes video transmission a hard to manage task. In this paper we evaluate the new emerging video coding standard HEVC and how it behaves under packet losses conditions in a VANET.

Low bit-rate video coding with 3d lower trees (3D-LTW)

The 3D-DWT is a mathematical tool of increasing importance in those applications that require an efficient processing of volumetric info However, the huge memory requirement of the algorithms that compute it is one of the main drawbacks in practical implementations In this paper, we introduce a fast frame-based 3D-DWT video encoder with low memory usage, based on lower-trees In this scheme, there is no need to divide the input video sequence into group of pictures (GOP), and it can be applied in a continuous manner, so that no boundary effects between GOPs appear.

On the Performance of Video Quality Assessment Metrics under Different Compression and Packet Loss Scenarios

When comparing the performance of video coding approaches, evaluating different commercial video encoders, or measuring the perceived video quality in a wireless environment, Rate/distortion analysis is commonly used, where distortion is usually measured in terms of PSNR values. However, PSNR does not always capture the distortion perceived by a human being. As a consequence, significant efforts have focused on defining an objective video quality metric that is able to assess quality in the same way as a human does. We perform a study of some available objective quality assessment metrics in order to evaluate their behavior in two different scenarios. First, we deal with video sequences compressed by different encoders at different bitrates in order to properly measure the video quality degradation associated with the encoding system. In addition, we evaluate the behavior of the quality metrics when measuring video distortions produced by packet losses in mobile ad hoc network scenarios with variable degrees of network congestion and node mobility. Our purpose is to determine if the analyzed metrics can replace the PSNR while comparing, designing, and evaluating video codec proposals, and, in particular, under video delivery scenarios characterized by bursty and frequent packet losses, such as wireless multihop environments.