Registration of holographic images based on the integral transformation

The paper describes the possibilities of using Fourier-Mellin transform for registering images of holographic interferograms. Registered holographic images will then allow automating their evaluation. Registration based on changes in image intensities using the discrete integral transforms was selected of the methods of registration. Whereas it was necessary to register the images, which are not only translated, but also rotated and with the changed of scale, the Fourier-Mellin transform was used. Use of the image discrete transforms is original in this field, proposed processing algorithm contains also simplified mean of calculating the angle of rotation of the test image instead of common Fourier-Mellin transformation method sequence

Optimization of manipulation logistics using data matrix codes

In the paper we deal with optimization of manipulation logistics using Data Matrix codes. Our goal is scanning and decoding Data Matrix codes in real-time. We have designed and verified an efficient computer aided method for location of the Data Matrix codes. This method is also suited to real-time processing and has been verified on a test set of images taken from real industrial world. We have proposed a modified, computationally efficient local thresholding technique that uses local mean and variation under the sliding window. The proposed Data Matrix code localization algorithm utilizes the connecting of the adjoining points into the continuous regions and determining of the boundaries of the outer region and it works in two basic steps: localization of the Finder Pattern and verification of the Timing Pattern. Part of the algorithm deals also with the decoding of the Data Matrix code using external libraries. Data Matrix codes can be used to mark logistic units, parts, warehousing positions, but also for automated robot navigation. Because of their low cost, accuracy, speed, reliability, flexibility and efficiency, as well as the ability to write large amounts of data on a small area, they still have a great advantage in logistics.[KEGA MS SR 003TU Z-4/2016

Ispitivanje temperaturnih polja u zraku iznad drva podvrgnutoga toplinskoj razgradnji

The paper deals with the visualization of thermal fields above the sample body while observing thermal loading of wood. Via holographic interferometry, thermal fields were visualized in a non-contact manner and the values were recorded in 0, 3, 7 and 15 minutes or earlier in case of degradation. In real time, the ongoing processes were recorded in the thermal boundary layer above the surface of sample bodies in dimensions of 43 mm × 40 mm × 10 mm of beech wood in three different directions: longitudinal, radial, tangential cut. The temperatures of isothermal curves above the heated samples and coefficients of heat transfer α were determined by a quantitative analysis of holographic interferograms. The heat transfer coefficient α ranged within 4.6-7.4 W/m2K. The simulation of heat transfer for the selected samples was prepared by the Fluent programme. Consequently, the measured values from the experiments were compared with the calculated values. There is a correlation between the measured and calculated values.Rad se bavi vizualizacijom toplinskih polja iznad površine uzorka tijekom zagrijavanja drva. Uz pomoć holografske interferometrije toplinska su polja beskontaktno vizualizirana nakon 0, 3, 7 i 15 minuta ili ranije u slučaju degradacije drva. U stvarnom vremenu zabilježeni su procesi u graničnome toplinskom sloju iznad površine uzorka od bukova drva dimenzija 43 mm × 40 mm × 10 mm u tri različita smjera: uzdužnome, radijalnome i tangencijalnome. Temperature izotermalnih krivulja iznad zagrijanih uzoraka i koeficijenti prolaska topline α određeni su kvantitativnom analizom holografskih interferograma. Koeficijent prolaska topline α kretao se u rasponu od 4,6 do 7,4 W/m2K. Simulacija prijenosa topline za odabrane uzorke napravljena je uz pomoć Fluent programa. Slijedom toga, vrijednosti izmjerene u istraživanju uspoređene su s izračunanim vrijednostima. Utvrđena je korelacija između izmjerenih i izračunanih vrijednosti

Possibility of Application of the User Interface of a Conventional Smartphone for Communication of Graphical Information with a Special HW/SW Device

This article is focused on enhancement of HW/SW device by cooperation with a smartphone interface. The device was a programmable Lego Mindstorms Education EV3 set in the form of a robot designed to solve the Rubik’s Cube. The aim of the research was to replace the built-in color sensor with a camera that would allow the cube scanning process to be accelerated. Two approaches were chosen to meet the goal: the NXTcam camera, accessible as an accessory to expand the set, and the camera built into the smartphone. The use of NXTcam led to better scan time, but this result was prone to external influences. The camera on the smartphone sped up the scanning process to 57% of the original time. The impact of external factors on the outcome was significantly lower, compared to NXTcam. In the experiment, the cube solving process was observed in natural light, with addition distractive light source and in artificial light

Impact of skeletonization methods on accuracy of digital holograms evaluation

The method of holographic interferometry has been applied to make the temperature fields over the heated-up wooden test specimens visible. We verified impact of skeletonization methods on accuracy of digital holograms evaluation. Individual thinning algorithms have individual approach to thinning and therefore resultant skeletons of digital holograms are different

Comparative Study of Data Matrix Codes Localization and Recognition Methods

We provide a comprehensive and in-depth overview of the various approaches applicable to the recognition of Data Matrix codes in arbitrary images. All presented methods use the typical “L” shaped Finder Pattern to locate the Data Matrix code in the image. Well-known image processing techniques such as edge detection, adaptive thresholding, or connected component labeling are used to identify the Finder Pattern. The recognition rate of the compared methods was tested on a set of images with Data Matrix codes, which is published together with the article. The experimental results show that methods based on adaptive thresholding achieved a better recognition rate than methods based on edge detection

Using Different Types of Artificial Neural Networks to Classify 2D Matrix Codes and Their Rotations—A Comparative Study

Artificial neural networks can solve various tasks in computer vision, such as image classification, object detection, and general recognition. Our comparative study deals with four types of artificial neural networks—multilayer perceptrons, probabilistic neural networks, radial basis function neural networks, and convolutional neural networks—and investigates their ability to classify 2D matrix codes (Data Matrix codes, QR codes, and Aztec codes) as well as their rotation. The paper presents the basic building blocks of these artificial neural networks and their architecture and compares the classification accuracy of 2D matrix codes under different configurations of these neural networks. A dataset of 3000 synthetic code samples was used to train and test the neural networks. When the neural networks were trained on the full dataset, the convolutional neural network showed its superiority, followed by the RBF neural network and the multilayer perceptron

Recognition of Data Matrix codes in images and their applications in production processes

Data Matrix codes can be a significant factor in increasing productivity and efficiency in production processes. An important point in deploying Data Matrix codes is their recognition and decoding. In this paper is presented a computationally efficient algorithm for locating Data Matrix codes in the images. Image areas that may contain the Data Matrix code are to be identified firstly. To identify these areas, the thresholding, connected components labelling and examining outer bounding-box of the continuous regions is used. Subsequently, to determine the boundaries of the Data Matrix code more precisely, we work with the difference of adjacent projections around the Finder Pattern. The dimensions of the Data Matrix code are determined by analyzing the local extremes around the Timing Pattern. We verified the proposed method on a testing set of synthetic and real scene images and compared it with the results of other open-source and commercial solutions. The proposed method has achieved better results than competitive commercial solutions