Search results for "Motion estimation"
showing 10 items of 56 documents
Speeding-Up Differential Motion Detection Algorithms Using a Change-Driven Data Flow Processing Strategy
2007
A constraint of real-time implementation of differential motion detection algorithms is the large amount of data to be processed. Full image processing is usually the classical approach for these algorithms: spatial and temporal derivatives are calculated for all pixels in the image despite the fact that the majority of image pixels may not have changed from one frame to the next. By contrast, the data flow model works in a totally different way as instructions are only fired when the data needed for these instructions are available. Here we present a method to speed-up low level motion detection algorithms. This method is based on pixel change instead of full image processing and good spee…
Selective Change Driven Vision Sensor With Continuous-Time Logarithmic Photoreceptor and Winner-Take-All Circuit for Pixel Selection
2015
The objective of Selective Change Driven (SCD) Vision is to capture and process those scene pixels that have the greatest impact in the motion estimation task. The implemented SCD Vision sensor delivers the pixels ordered according to the illumination change undergone by each pixel, from the last time each pixel was read-out. This ordering strategy is especially interesting for motion detection algorithms, since it allows for a reduction in data bandwidth requirements without decreasing accuracy. The speed of the obtained pixel flow allows movement detection and tracking at a speed several orders of magnitude higher than conventional vision systems. To accomplish these objectives, the senso…
Meta-Tracking for Video Scene Understanding
2013
International audience; This paper presents a novel method to extract dominant motion patterns (MPs) and the main entry/exit areas from a surveillance video. The method first computes motion histograms for each pixel and then converts it into orientation distribution functions (ODFs). Given these ODFs, a novel particle meta-tracking procedure is launched which produces meta-tracks, i.e. particle trajectories. As opposed to conventional tracking which focuses on individual moving objects, meta-tracking uses particles to follow the dominant flow of the traffic. In a last step, a novel method is used to simultaneously identify the main entry/exit areas and recover the predominant MPs. The meta…
Joint image and motion reconstruction for PET using a B-spline motion model.
2012
We present a novel joint image and motion reconstruction method for PET. The method is based on gated data and reconstructs an image together with a motion function. The motion function can be used to transform the reconstructed image to any of the input gates. All available events (from all gates) are used in the reconstruction. The presented method uses a B-spline motion model, together with a novel motion regularization procedure that does not need a regularization parameter (which is usually extremely difficult to adjust). Several image and motion grid levels are used in order to reduce the reconstruction time. In a simulation study, the presented method is compared to a recently propos…
Optimizing H.264/AVC interprediction on a GPU-based framework
2011
H.264/MPEG-4 part 10 is the latest standard for video compression and promises a significant advance in terms of quality and distortion compared with the commercial standards currently most in use such as MPEG-2 or MPEG-4. To achieve this better performance, H.264 adopts a large number of new/improved compression techniques compared with previous standards, albeit at the expense of higher computational complexity. In addition, in recent years new hardware accelerators have emerged, such as graphics processing units (GPUs), which provide a new opportunity to reduce complexity for a large variety of algorithms. However, current GPUs suffer from higher power consumption requirements because of…
Visual motion integration controls attractiveness of objects in walking flies and a mobile robot
2008
Walking fruit flies are attracted by near-by objects. They estimate the distance to these objects by the parallax motion of their images on the retina. Here we provide evidence from robot simulations that distance is assessed by motion integration over large parts of the visual field and time periods of 0.5 s to 2 s. The process in flies is not selective to image motion created by the self-motion of the fly but also sensitive to object motion and to the pattern contrast of objects. Added visual motion (e.g. oscillations) makes objects more attractive than their stationary counterparts. Front-to-back motion, the natural parallax motion on the eyes of a forward-translating fly, is preferred. …
Cloud motion detection from infrared satellite images
2002
The estimation of cloud motion from a sequence of satellite images can be considered a challenging task due to the complexity of phenomena implied. Being a non-rigid motion and implying non-linear events, most motion models are not suitable and new algorithms have to be developed. We propose a novel technique, combining a Block Matching Algorithm (BMA) and a best candidate block search along with a vector median regularisation.
Restoration of Vertical Line Scratches with a Distributed Genetic Algorithm
2006
This contribution approaches the problem of scratch restoration in old movies as a optimisation's problem. The functional based on the statistical properties of the image around the scratch is optimised using an ad-hoc genetic algorithm. Given the large amount of the computational time needed by genetic algorithms, a network of standard workstations with heterogeneous operating systems has been used. Each workstation in the network works on each scratch to perform the restoration, and a specific machine works as root node with the task of distributing jobs on the network and adding the outputted restored scratches back into the image.
Video Indexing Using MPEG Motion Compensation Vectors
2003
In the last years a lot of work has been done on color, textural, structural and semantic indexing of "content-based" video databases. Motion-based video indexing has been less explored, with approaches generally based on the analysis of optical flows. Compressed videos require the decompression of the sequences and the computation of optical flows, two steps computationally heavy. In this paper we propose some methods to index videos by motion features (mainly related to camera motion) and by motion-based spatial segmentation of frames, in a fully automatic way. Our idea is to use MPEG motion vectors as an alternative to optical flows. Their extraction is very simple and fast; it doesn't r…
Video indexing using optical flow field
2002
The increasing development of advanced multimedia applications requires new technologies for organizing and retrieving by content databases of digital video. Several content based features (color, texture, motion, etc.) are needed to perform a reliable content based retrieval. We present a method for automatic motion based video indexing and retrieval. A prototypal system has been developed to prove the validity of our approach. Our system automatically splits a video into a sequence of shots, extracts a few representative frames (said r-frames) from each shot and computes some motion based features related to the optical flow field. Motion based queries are then performed either in a quali…