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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.

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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.

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Rozpoznawanie tekstur z wykorzystaniem bazy modeli

Szymczyk T.

Prace Instytutu Elektrotechniki

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2011

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Z. 249

95-115

PL

Problem rozpoznawania obrazów jest zagadnieniem trudnym i złożonym. Jednym z możliwych sposobów jego realizacji, jest wykorzystanie bazy modeli i porównywanie ich z obrazem badanym pochodzącym z kamery. Możliwe jest rozpoznawanie w oparciu o: kształt, kolor czy też teksturę. W artykule zaprezentowano wykorzystanie zmodyfikowanej metody dopasowania wzorców do rozpoznawania obrazów, pochodzących z rzeczywistej kamery przemysłowej. Przedstawiono także podstawowe wady i ograniczenia klasycznej metody dopasowania wzorców.

EN

The problem of the image recognizing is difficult and complex question. The using the base of models and comparing their to image from camera is one of possible ways of his realization. Image recognizing is possible in support about shape, colour or texture also. In article modified method template matching to recognizing images from real industrial camera was presented. Moreover basic disadvantages and limitations of simple template matching method was shown in the paper.

4

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.