20,370 research outputs found
Comparative Study and Optimization of Feature-Extraction Techniques for Content based Image Retrieval
The aim of a Content-Based Image Retrieval (CBIR) system, also known as Query
by Image Content (QBIC), is to help users to retrieve relevant images based on
their contents. CBIR technologies provide a method to find images in large
databases by using unique descriptors from a trained image. The image
descriptors include texture, color, intensity and shape of the object inside an
image. Several feature-extraction techniques viz., Average RGB, Color Moments,
Co-occurrence, Local Color Histogram, Global Color Histogram and Geometric
Moment have been critically compared in this paper. However, individually these
techniques result in poor performance. So, combinations of these techniques
have also been evaluated and results for the most efficient combination of
techniques have been presented and optimized for each class of image query. We
also propose an improvement in image retrieval performance by introducing the
idea of Query modification through image cropping. It enables the user to
identify a region of interest and modify the initial query to refine and
personalize the image retrieval results.Comment: 8 pages, 16 figures, 11 table
Partial 3D Object Retrieval using Local Binary QUICCI Descriptors and Dissimilarity Tree Indexing
A complete pipeline is presented for accurate and efficient partial 3D object
retrieval based on Quick Intersection Count Change Image (QUICCI) binary local
descriptors and a novel indexing tree. It is shown how a modification to the
QUICCI query descriptor makes it ideal for partial retrieval. An indexing
structure called Dissimilarity Tree is proposed which can significantly
accelerate searching the large space of local descriptors; this is applicable
to QUICCI and other binary descriptors. The index exploits the distribution of
bits within descriptors for efficient retrieval. The retrieval pipeline is
tested on the artificial part of SHREC'16 dataset with near-ideal retrieval
results.Comment: 19 pages, 17 figures, to be published in Computers & Graphic
The relationship between IR and multimedia databases
Modern extensible database systems support multimedia data through ADTs. However, because of the problems with multimedia query formulation, this support is not sufficient.\ud
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Multimedia querying requires an iterative search process involving many different representations of the objects in the database. The support that is needed is very similar to the processes in information retrieval.\ud
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Based on this observation, we develop the miRRor architecture for multimedia query processing. We design a layered framework based on information retrieval techniques, to provide a usable query interface to the multimedia database.\ud
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First, we introduce a concept layer to enable reasoning over low-level concepts in the database.\ud
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Second, we add an evidential reasoning layer as an intermediate between the user and the concept layer.\ud
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Third, we add the functionality to process the users' relevance feedback.\ud
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We then adapt the inference network model from text retrieval to an evidential reasoning model for multimedia query processing.\ud
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We conclude with an outline for implementation of miRRor on top of the Monet extensible database system
Panako: a scalable acoustic fingerprinting system handling time-scale and pitch modification
In this paper a scalable granular acoustic fingerprinting system robust against time and pitch scale modification is presented. The aim of acoustic fingerprinting is to identify identical, or recognize similar, audio fragments in a large set using condensed representations of audio signals, i.e. fingerprints. A robust fingerprinting system generates similar fingerprints for perceptually similar audio signals. The new system, presented here, handles a variety of distortions well. It is designed to be robust against pitch shifting, time stretching and tempo changes, while remaining scalable. After a query, the system returns the start time in the reference audio, and the amount of pitch shift and tempo change that has been applied. The design of the system that offers this unique combination of features is the main contribution of this research. The fingerprint itself consists of a combination of key points in a Constant-Q spectrogram. The system is evaluated on commodity hardware using a freely available reference database with fingerprints of over 30.000 songs. The results show that the system responds quickly and reliably on queries, while handling time and pitch scale modifications of up to ten percent
An Efficient Index for Visual Search in Appearance-based SLAM
Vector-quantization can be a computationally expensive step in visual
bag-of-words (BoW) search when the vocabulary is large. A BoW-based appearance
SLAM needs to tackle this problem for an efficient real-time operation. We
propose an effective method to speed up the vector-quantization process in
BoW-based visual SLAM. We employ a graph-based nearest neighbor search (GNNS)
algorithm to this aim, and experimentally show that it can outperform the
state-of-the-art. The graph-based search structure used in GNNS can efficiently
be integrated into the BoW model and the SLAM framework. The graph-based index,
which is a k-NN graph, is built over the vocabulary words and can be extracted
from the BoW's vocabulary construction procedure, by adding one iteration to
the k-means clustering, which adds small extra cost. Moreover, exploiting the
fact that images acquired for appearance-based SLAM are sequential, GNNS search
can be initiated judiciously which helps increase the speedup of the
quantization process considerably
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