Fold cracking of coated papers: investigation on automated computer-aided visual assessment method

Pál, Magdolna; Dedijer, Sandra; Koltai, László; Gregor-Svetec, Diana; Cigula, Tomislav; Pavlović, Živko; Milić-Keresteš, Neda

doi:10.1515/npprj-2021-0041

“…White areas on the images of the coated paper samples are correlated to the surface damages that occurred during the folding process (Rättö & Hornatowska, 2010;Yang & Xie, 2011;Barbier et al, 2012;Rättö et al, 2012;Sim et al, 2012;Oh et al, 2015;Oh et al, 2016;Pál et al, 2017;Rajabi Abhari et al, 2018;Najafi et al, 2019b;Wang & Ding, 2020;Pál et al, 2021). To determine the white pixels` percentage on the digitized folded paper samples and the corresponding additional image features, an image processing algorithm has been developed with the following requirements (Sinha, 2000;Apro et al, 2011;Malek, 2012;Takemetoyo et al, 2007;Nashat et al, 2014;Goncalves et al, 2015;Sengupta et al, 2015): autonomous work, noise suppression, accurate surface damage mapping to the binary image, computationally as simple as a possible solution.…”

Section: Image Analysis and Feature Extractionmentioning

confidence: 99%

“…To reduce the negative effects of folding process, the fold cracking resistance was gaining importance and has become an active field of research. Along with the commonly used mechanical testing methods, different computer-aided assessments have been introduced lately as new techniques for quantitative surface damage characterisation (Barbier et al, 2002;Rättö & Hornatowska, 2010;Yang & Xie, 2011;Rättö et al, 2012;Sim et al, 2012;Oh et al, 2015;Oh et al, 2016;Pál et al, 2017;Rajabi Abhari et al, 2018;Najafi et al, 2019;Wang & Ding, 2020;Pál et al, 2021). These newly proposed methods are based on image processing and analysis and have similar basic concept of damage registration, digitization, and image feature calculus.…”

mentioning

confidence: 99%

Statistical approach in fold crack distribution analysis

Pál¹,

Dedijer²,

Jurić³

et al. 2022

Proceedings - The Eleventh International Symposium GRID 2022

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The folding process is one of the most commonly used print finishing operations in graphical production. Therefore, surface damages on coated papers and paperboards, which are frequently appearing during this process, can have significant negative economic and environmental impacts. To reduce the adverse effects, fold crack resistance has become an active field of research. In the last decades, there were several computer-aided visual assessment methods introduced for fold-crack evaluation. These techniques were based on similar concepts of digital image analysis to quantitatively characterise the surface damage, but they had differences in utilisation as well as in the used image feature. In this study, fold crack distribution has been introduced as a new digital image feature for quality assessment. Fold crack distribution can be determined as a measure of crack scattering over the folding line. In this paper descriptive statistics, mean value, standard deviation and coefficient of variance have been used for qualitative characterisation of surface damage. The obtained results for mean value demonstrated increasing tendency by increasing the basis weight and had slightly lower value for samples in machine than cross direction. These results confirm the basic assumptions that on thicker substrates (i.e. on samples with higher basis weight) the cracks are larger, longer or grouped and that the folding process generates higher surface destruction is cross than machine direction. In the case of standard deviation, results suggest that in a case of varying mean values, crack distribution should be defined via coefficient of variation. Based on this analysis, the proposed approach to the calculation of crack distribution can serve as a new image characteristic for the qualitative measurement of the fold-crack resistance of coated papers.

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“…White areas on the images of the coated paper samples are correlated to the surface damages that occurred during the folding process (Rättö & Hornatowska, 2010;Yang & Xie, 2011;Barbier et al, 2012;Rättö et al, 2012;Sim et al, 2012;Oh et al, 2015;Oh et al, 2016;Pál et al, 2017;Rajabi Abhari et al, 2018;Najafi et al, 2019b;Wang & Ding, 2020;Pál et al, 2021). To determine the white pixels` percentage on the digitized folded paper samples and the corresponding additional image features, an image processing algorithm has been developed with the following requirements (Sinha, 2000;Apro et al, 2011;Malek, 2012;Takemetoyo et al, 2007;Nashat et al, 2014;Goncalves et al, 2015;Sengupta et al, 2015): autonomous work, noise suppression, accurate surface damage mapping to the binary image, computationally as simple as a possible solution.…”

Section: Image Analysis and Feature Extractionmentioning

confidence: 99%

“…To reduce the negative effects of folding process, the fold cracking resistance was gaining importance and has become an active field of research. Along with the commonly used mechanical testing methods, different computer-aided assessments have been introduced lately as new techniques for quantitative surface damage characterisation (Barbier et al, 2002;Rättö & Hornatowska, 2010;Yang & Xie, 2011;Rättö et al, 2012;Sim et al, 2012;Oh et al, 2015;Oh et al, 2016;Pál et al, 2017;Rajabi Abhari et al, 2018;Najafi et al, 2019;Wang & Ding, 2020;Pál et al, 2021). These newly proposed methods are based on image processing and analysis and have similar basic concept of damage registration, digitization, and image feature calculus.…”

Section: Introductionmentioning

confidence: 99%

Proceedings - The Eleventh International Symposium GRID 2022

2022

0

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It is my great pleasure to introduce You the research papers of the Eleventh Symposium on Graphic Engineering and Design.With this proceeding we continue the works of previous symposiums which have been held biennial since year 2002.We're delighted that this international symposium has once again gatered a great number of participants from many countries as it became a tradition over the past 20 years.The papers include the achievements of researches in the field of technology and scientific areas relevant to graphic technology and graphic design. Through the work of the symposium GRID we continued significant scientific cooperation with educational institutions all over the world. With them we are continuing good cooperation which is the driving force for the creation and display of new developments, both individual and common. I want to thank everyone who participated with their paper and presentation in the Symposium. Your contribution is significant for the improvement of the Symposium on Graphic Engineering and Design GRID 22. The research achievements presented here are also valuable to the scientific and professional community and are highly appreciated.

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Assessment of paperboard large deformation at fold using digital image correlation technique

Mirzaei

¹

,

Johnson

²

,

Panek

³

et al. 2023

Nordic Pulp &Amp; Paper Research Journal

1

0

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For coated paperboard with large deformations, there is limited knowledge on the mechanisms that lead to coating damage and on the key properties that affect damage. Large deformations produce complex non-linear mechanical responses which often result in significant internal damage. The objective of this work was to establish methods to directly measure local deformation at a fold using a stereo digital image correlation (DIC) technique and a folding device designed in-house. This allowed monitoring of deformation from both cross-section and surface views, from which curvature and strain could be analyzed. This approach allowed observation and quantification of the initiation and propagation of damage. Testing showed that elastic estimation of deformation is valid only at very small curvatures but is still qualitatively useful. It was found that CD fold line shows a lower strain than MD fold line at a given curvature, but it ultimately reaches a higher level of surface strain. Additionally, localized maximum surface strain was shown to correlate better with surface damage at fold than the average surface strain. Furthermore, the introduced discontinuity index can provide a useful tool to compare surface damage at fold even for paperboard samples with different thicknesses.

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Fold cracking of coated papers: investigation on automated computer-aided visual assessment method

Cited by 3 publications

References 52 publications

Statistical approach in fold crack distribution analysis

Statistical approach in fold crack distribution analysis

Proceedings - The Eleventh International Symposium GRID 2022

Assessment of paperboard large deformation at fold using digital image correlation technique

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