Wyniki wyszukiwania - BazTech

1

Template Matching Using Improved Rotations Fourier Transform Method

Wijaya Marvin Chandra

International Journal of Electronics and Telecommunications

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2022

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Vol. 68. No. 4

881--888

EN

Template matching is a process to identify and localize a template image on an original image. Several methods are commonly used for template matching, one of which uses the Fourier transform. This study proposes a modification of the method by adding an improved rotation to the Fourier transform. Improved rotation in this study uses increment rotation and three shear methods for the template image rotation process. The three shear rotation method has the advantage of precise and noisefree rotation results, making the template matching process even more accurate. Based on the experimental results, the use of 10°angle increments has increased template matching accuracy. In addition, the use of three shear rotations can improve the accuracy of template matching by 13% without prolonging the processing time.

2

Comparison of three methods for reconstructing 3D motion from 2D video recordings for low cost gait analysis systems

Cygan Szymon, Specyalska Adriana

Polish Journal of Medical Physics and Engineering

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2021

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Vol. 27, Iss. 4

271--277

EN

Purpose: The aim of this study was to quantify the accuracy of 3D trajectory reconstructions performed from two planar video recordings, using three different reconstruction methods. Additionally, the recordings were carried out using easily available equipment, like built-in cellphone cameras, making the methods suitable for low-cost applications. Methods: A setup for 3D motion tracking was constructed and used to acquire 2D video recordings subsequently used to reconstruct the 3D trajectories by 1) merging appropriate coordinates, 2) merging coordinates with proportional scaling, and 3) calculating the 3D position based on markers’ projections on the viewing plane. As experimental verification, two markers moving at a fixed distance of 98.9 cm were used to assess the consistency of results. Next, gait analysis in five volunteers was carried out to quantify the differences resulting from different reconstruction methods. Results: Quantitative evaluation of the investigated 3D trajectories reconstruction methods showed significant differences between those methods, with the worst reconstruction approach resulting in a maximum error of 50% (standard deviation 13%), while the best resulting in a maximum error of 1% (standard deviation 0.44%). The gait analysis results showed differences in mean angles obtained with each reconstruction method reaching only 2°, which can be attributed to the limited measurement volume. Conclusions: Reconstructing 3D trajectory from 2D views without accounting for the “perspective error” results in significant reconstruction errors. The third method described in this study enables a significant reduction of this issue. Combined with the proposed setup, it provides a functional, low-cost gait analysis system.

3

Pick-and-place task implementation using visual open-loop control

Kołosowski Paweł, Wolniakowski Adam, Bogdan Mariusz

Acta Mechanica et Automatica

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2019

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Vol. 13, no. 3

211--216

EN

In the ever increasing number of robotic system applications in the industry, the robust and fast visual recognition and pose estimation of workpieces are of utmost importance. One of the ubiquitous tasks in industrial settings is the pick-and-place task where the object recognition is often important. In this paper, we present a new implementation of a work-piece sorting system using a template matching method for recognizing and estimating the position of planar workpieces with sparse visual features. The proposed framework is able to distinguish between the types of objects presented by the user and control a serial manipulator equipped with parallel finger gripper to grasp and sort them automatically. The system is furthermore enhanced with a feature that optimizes the visual processing time by automatically adjusting the template scales. We test the proposed system in a real-world setup equipped with a UR5 manipulator and provide experimental results documenting the performance of our approach.

4

Feature extraction and template matching algorithm classification for PCB fiducial verification

Fonseka C. L. S. C., Jayasinghe J. A. K. S.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 86, nr 1

14--32

EN

Purpose: Automatic Optical Inspection (AOI) systems that are extensively used in the industry of Electronics Manufacturing Services (EMS), performs the inspection of Surface Mount Devices (SMD). One of the main tasks of such an AOI system is to align a given PCB to the parameters of the corresponding PCB positioning system by a process called fiducial alignment. However, no detailed analysis has been carried out so far on the methodologies that can be used to have a very precise identification of PCB fiducial points. In our research, we have implemented an AOI system for the inspection of soldering defects of Through Hole Technology (THT) solder joints, which can be integrated to a desktop soldering robotic platform. Such platforms are used in environments where no specific lighting conditions can be provided within a surrounded atmosphere. Therefore, an AOI system that is capable of performing fiducial alignment of any given PCB under varying lighting condition is highly preferred. In this paper, we have presented a detailed analysis on feature extraction and template matching algorithms that can be used to implement a very precise fiducial verification process under normal lighting condition. Design/methodology/approach: A detailed analysis and performance evaluation have been carried out in this paper on prominent image comparison algorithms that are extensively used in the field of image processing. Findings: According to the analysis carried out in this paper, it could be observed that the combination of feature extraction and template matching algorithms gives the best performance in PCB fiducial verification process. Research limitations/implications: This paper only presents the implementation of the front end of our proposed AOI system. The implemented methodologies for the automatic identification of soldering defects will be discussed in separate research papers. Practical implications: The methodologies presented in this paper can be effectively used to implement a very precise and robust PCB fiducial verification process that can be efficiently integrated to a desktop soldering robotic system. Originality/value: This research proposes a very accurate fiducial verification process that can be used under varying lighting conditions on a wide range of different PCB fiducial points.

5

Control of speed and direction of electric wheelchair using seat pressure mapping

Hori J., Ohara H., Inayoshi S.

Biocybernetics and Biomedical Engineering

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2018

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Vol. 38, no. 3

624--633

EN

An electric wheelchair controlled through seat pressure mapping was developed to accomplish hands-free operation. The seat pressure mapping resulting from a change in posture was measured using a pressure sensor array seated on the wheelchair in real time. The movements of the upper body were discriminated using template matching. The speed and direction can be controlled based on the similarities between the measured pressure distribution and five templates of neutral, forward, backward, left, and right movements. The developed interface was built into a commercial electric wheelchair. As the results of an experiment show, the proposed wheelchair can be controlled in any direction and velocity.

6

Brain abnormality detection using template matching

Praveen G. B., Agrawal A., Pareek S., Prince A.

Bio-Algorithms and Med-Systems

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2018

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Vol. 14, no. 4

art. no. 20180029

EN

Magnetic resonance imaging (MRI) is a widely used imaging modality to evaluate brain disorders. MRI generates huge volumes of data, which consist of a sequence of scans taken at different instances of time. As the presence of brain disorders has to be evaluated on all magnetic resonance (MR) sequences, manual brain disorder detection becomes a tedious process and is prone to inter- and intra-rater errors. A technique for detecting abnormalities in brain MRI using template matching is proposed. Bias filed correction is performed on volumetric scans using N4ITK filter, followed by volumetric registration. Normalized cross-correlation template matching is used for image registration taking into account, the rotation and scaling operations. A template of abnormality is selected which is then matched in the volumetric scans, if found, the corresponding image is retrieved. Post-processing of the retrieved images is performed by the thresholding operation; the coordinates and area of the abnormality are reported. The experiments are carried out on the glioma dataset obtained from Brain Tumor Segmentation Challenge 2013 database (BRATS 2013). Glioma dataset consisted of MR scans of 30 real glioma patients and 50 simulated glioma patients. NVIDIA Compute Unified Device Architecture framework is employed in this paper, and it is found that the detection speed using graphics processing unit is almost four times faster than using only central processing unit. The average Dice and Jaccard coefficients for a wide range of trials are found to be 0.91 and 0.83, respectively.

7

Development of Data Processing Tools for the Analysis of Radargrams in Utility Detection Using Ground Penetrating Radar

Sagnard F.

Journal of Telecommunications and Information Technology

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2017

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nr 3

55--68

EN

The extraction of quantitative information from Ground Penetrating Radar (GPR) data sets (radargrams) to detect and map underground utility pipelines is a challenging task. This study proposes several algorithms included in the main stages of a data processing chain associated with radargrams. It comprises preprocessing, hyperbola enhancing, hyperbola detection and localization, and parameter extraction. Additional parameters related to the GPR system such as the frequency band and the polarization bring data sets additional information that need to be exploited. Presently, the algorithms have been applied step by step on synthetic and experimental data. The results help to guide future developments in signal processing for quantitative parameter estimation.

8

Optimal classification method for smiling vs neutral facial display recognition

Nurzyńska K., Smołka B.

Journal of Medical Informatics & Technologies

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2014

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Vol. 23

87--94

EN

Human face depicts what happens in the soul, therefore correct recognition of emotion on the basis of facial display is of high importance. This work concentrates on the problem of optimal classification technique selection for solving the issue of smiling versus neutral face recognition. There are compared most frequently applied classification techniques: k-nearest neighbourhood, support vector machines, and template matching. Their performance is evaluated on facial images from several image datasets, but with similar image description methods based on local binary patterns. According to the experiments results the linear support vector machine gives the most satisfactory outcomes for all conditions.

9

Rozpoznawanie gestów wykonywanych dłońmi na podstawie pojedynczych obrazów

Koszowski G.

Studia Informatica

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2013

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Vol. 34, nr 2A

379--392

PL

Artykuł zawiera wyniki 3 grup algorytmów stosowanych do rozpoznawania gestów wykonywanych dłońmi na podstawie pojedynczych obrazów. Algorytmy te opierają się na: dopasowaniu szablonów masek binarnych obrazów, metodach opartych na konturach dłoni w obrazie oraz detekcji reprezentantów punktów reprezentujących krzywizny konturów dłoni. Wyniki uzyskano na podstawie 3 baz danych, w których obrazy zostały podzielone na bazę testową i referencyjną. Jedna baza referencyjna została wygenerowana na podstawie modelu 3D.

EN

This Paper include results of 3 groups of algorithms used to hand pose gesture recognition based on single images. Those algorithms base on: Template Matching of binary masks from images, methods based on hand contours in image and the Points representing points from curvatures detection. Results were obtained with 3 databases, which images were split for test and reference database. One of reference databases was generated from the 3D model.

10

The application of simple shape measures based on a Minimum Bounding Rectangle to the General Shape Analysis problem

Frejlichowski D., Gościewska K.

Journal of Theoretical and Applied Computer Science

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2013

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Vol. 7, nr 4

35--41

EN

This paper deals with the problem of General Shape Analysis. Simple shape measures based on a minimum bounding rectangle are investigated so as to obtain and compare general shape characteristics. The goal of General Shape Analysis is to find for each test object the one or few most similar templates. Thanks to this we can determine general information about a shape, such as how rectangular it is. Our work involves trying to find a shape descriptor that is simple to derive, allows for fast matching, and is the most consistent with a human benchmark that has been collected from the appropriate inquiry forms. Some experiments using various simple shape measures were performed. A concise explanation of these experiments and some percentage accuracy results are provided in this paper.

11

Inter-frame Prediction with Fast Weighted Low-rank Matrix Approximation

Huang Z. L., Hsiao H. F.

International Journal of Electronics and Telecommunications

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2013

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Vol. 59, No. 1

9-16

EN

In the field of video coding, inter-frame prediction plays an important role in improving compression efficiency. The improved efficiency is achieved by finding predictors for video blocks such that the residual data can be close to zero as much as possible. For recent video coding standards, motion vectors are required for a decoder to locate the predictors during video reconstruction. Block matching algorithms are usually utilized in the stage of motion estimation to find such motion vectors. For decoder-side motion derivation, proper templates are defined and template matching algorithms are used to produce a predictor for each block such that the overhead of embedding coded motion vectors in bit-stream can be avoided. However, the conventional criteria of either block matching or template matching algorithms may lead to the generation of worse predictors. To enhance coding efficiency, a fast weighted low-rank matrix approximation approach to deriving decoder-side motion vectors for inter frame video coding is proposed in this paper. The proposed method first finds the dominating block candidates and their corresponding importance factors. Then, finding a predictor for each block is treated as a weighted low-rank matrix approximation problem, which is solved by the proposed column-repetition approach. Together with mode decision, the coder can switch to a better mode between the motion compensation by using either block matching or the proposed template matching scheme.

12

Metoda dopasowania wzorców w rozpoznawaniu obrazów - ograniczenia, problemy i modyfikacje metody

Szymczyk T.

Automatyka / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2008

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T. 12, z. 2

449-462

PL

Metoda dopasowania wzorców znalazła wiele zastosowań. Stosuje się ją z powodzeniem do rozpoznawania zarówno prostych binarnych konturów, jak i do dynamicznego rozpoznawania obiektów w sekwencjach wideo. Pomimo prostoty i ułomności metody jest ona nadal stosowana i rozwijana. W artykule przedstawiono ewolucję rozpoznawania obiektów bazujących na modelu. Autor przedstawia rozpoznawanie obrazów w kontekście rozpoznawania tekstury. Zastosowano proste przekształcenie powodujące znaczną poprawę działania metody dopasowania wzorców. Przekształcenie to jak się okazało, nie zwiększa w sposób znaczący czasu obliczeń.

EN

The method of the template matching has found many applications. It is used successfully in recognition of simple binary contours and also in dynamic recognition of the objects in video sequences. It is still applied and developed despite the simplicity and numerous deficiencies of the method. In the paper the evolution of recognizing objects based on the model was introduced. The author presents recognition of the pictures in the context of the texture recognizing. Simple transformation resulting in the considerable improvement of the operation of the template matching method was applied. It has been observed that this transformation does not enlarge significantly the time and the cost of the calculations.

13

Template matching by means of correlation coefficient for detecting cancerous masses in mammograms

Bator M., Nieniewski M.

Machine Graphics and Vision

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2007

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Vol. 16, No. 3/4

329-345

EN

The paper presents the authors' experiences with the detection of cancerous masses in mammograms. The described detection method is based on the use of multiscale template matching and multiresolution. As a measure of similarity, the correlation coefficient is adapted. The main conclusion drawn from the conducted experiments is that by sufficiently dense scaling of the templates one can achieve FROC (Free Response Operating Characteristics) curves of the same quality as the curves obtained in the literature with considerably more sophisticated methods. The results were calculated for full mammograms of the entire MIAS database, in contrast to the literature, where the results are often given for regions of interest or for selected images. Several options for the templates were investigated, including three variants based on the hemispherical gray level distribution, as well as the optimal choice of the increasing scale of templates covering the whole range of diameters of masses.

14

Two template matching approaches to Arabic, Amharic and Latin isolated characters recognition

Cowell J., Hussain F.

Machine Graphics and Vision

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2005

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Vol. 14, No. 2

213-232

EN

With the establishment of commercial OCR systems for Latin text, recent research efforts have been directed at the design of recognition systems for non-Latin scripts, such as Japanese, Cyrillic, Chinese, Hindi, Tibetan, and in particular Arabic. The Unicode 4.0 standard supports 50 scripts that are used across the world, and many, such as Amharic (Ethiopic), have attracted virtually no attention from researchers. An extensive literature review reveals no papers which report on an OCR system for Amharic. This paper describes a normalised technique which can be used for recognition of isolated Arabic, Amharic and Latin characters. Two approaches are considered for identifying the characters by comparing them to a series of templates and using a signature template scheme. The degrees of similarity between pairs of Amharic, Arabic and typical Latin characters are presented in the confusion matrix, and the performance of the two approaches is compared for each of these three character sets.

15

Fast and efficient algorithm for face detection in colour images

Kukharev G., Nowosielski A.

Machine Graphics and Vision

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2004

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Vol. 13, No. 4

377-399

EN

Detecting human faces automatically is an indispensable step in any system that exploits information content in a face. The surveillance systems are of particular interest in that field. To correctly recognize a person from an input image, presence and location of the head must be determined in the first step. If the face detection subsystems fails, the performance of the whole system suffers. In the article a scheme for detecting faces in colour images is proposed. It utilizes the skin colour method with a new approach to detecting skin colour pixels in the RGB colour space. The edge information is used to increase the distinction between the skin-coloured face patches and the background. It is followed by a scan line candidate determination algorithm. A new method (combining profiles, geometrical moments, the use of the R-B colour subspace and grey level images) for eyes localization is presented. The verification is finally made based on a well-known template matching approach. After new methods and modifications were evaluated, a system based on the proposed scheme was built and tested.