(IJACSA) International Journal of Advanced Computer Science and Applications, Vol. 13, No. 4, 2022 Image Analysis of Heat-Affected Zone of Laser-Cut Heat-Resistant Paper using Otsu Thresholding Technique Shalida Mohd Rosnan 1 Graduate School of Life and Environmental Sciences University of Tsukuba Tsukuba, Japan Kong Peifu 2 Degree Programs in Life and Earth Sciences University of Tsukuba Tsukuba, Japan Toshiharu Enomae 3 , Nakagawa- Izumi Akiko 4 Faculty of Life and Environmental Sciences University of Tsukuba Tsukuba, Japan Abstract—Since ancient times, natural fibers have been essential in paper production and packaging fabrication. However, beauty-marring carbonization, or a heat-affected zone (HAZ) generated during the laser cutting process of paper materials led to an intriguing discussion on the possibility of reducing this defect zone. Thus, paper loaded with aluminum hydroxide [Al(OH) 3 ] (AH) was prepared and tested with laser cutting. There were two input parameters of laser processing: the ratio of laser power to a maximum and the cutting speed. The study discussed the HAZ area of the paper with AH loaded at 0– 40% on a dry pulp basis. The HAZ area was measured through image processing software. The Otsu thresholding technique (OTT) was applied to HAZ area determinations. The results from the image analysis signified that the smallest HAZ area was successfully achieved on samples with AH loaded at 40%. The optimal condition for the sample with 40% AH loaded was 60% power ratio and 20 mm/s in cutting speed. Based on the results, the cutting speed was the most significant parameter to produce the smallest HAZ area; therefore, the laser processing parameters were optimized to achieve a minimum HAZ area, and it was possible to reduce its dark color appearance of the material surfaces. Based on this study, it was found that the application of the Otsu thresholding technique was of significance to the HAZ area determination and reduction of the time consumption for the image analysis. Keywords—Heat-affected zone; image analysis; image processing; laser cutting; thresholding I. INTRODUCTION The digital image may be described as the two-dimensional function which refers to f (x, y). To make it easy to understand, pairs of x and y are plane or spatial coordinates, and the amplitude of function f at any coordinates of x, y is called gray level or scale. Thus, when x, y, and f are all finite, we call the function f a digital image. The digital image processing is performed with a computer [1] its techniques has been widely thriven and they are now used for all kinds of tasks in various areas such as image recognition technology along with computer vision and thresholding techniques [2]. Image analysis is an area related with image processing and the extraction of useful information from an image is beneficial to various fields ranging from computer vision applications to medical bioimaging analyses. Vision is the most advanced human senses; however, our vison is limited to the visual band of the electromagnetic spectrum. Thus, imaging machines such as electron microscopy, and computer-generated images used to operate on images [1]. Thus, digital image processing and analysis so popular nowadays and encompasses a varied field of applications. There is almost no technical area that is not impacted by the digital image processing. In our case, it is crucial to extract useful information from images that can help determine the HAZ and improve the laser cutting process. In the laser cutting process, image processing techniques and image analysis are helpful for HAZ determination. The laser cutting process has recently become a fascinating element in paper-based product fabrication. This is because of the wide range of applications from cutting to engraving [3], perforating, and designing complex geometrics [3]–[8]. Moreover, due to the growing personal needs as well as product quality and high productivity, it is convenient to apply laser cutting technology. However, carbonization and heat- affected zone (HAZ) seem to lead to an intriguing discussion on whether reducing the HAZ in the laser cutting process is possible. Laser cutting is an efficient method for cutting materials as it can be operated readily. Through understanding, high-quality cutting optimal parameters can be obtained. Even though laser cutting has been applied since the 1990s for cutting, perforating, and creasing paper materials, unfortunately, only a few works in literature have been discussed using the laser process of paper products. The mechanisms of laser cutting for paper or other wood-based materials are a thermochemical decomposition [8][9]involving vaporization, meaning the paper material reacts to heat generated by laser beam irradiation and evaporates from the surface. The study of laser cutting quality focused on two laser processing output which are HAZ and kerf of the cuts. However, in this study, only the HAZ output will be discussed. To analyze the HAZ quality, image analysis needed to determine the optimal setting of the laser process. Over the years, image processing and image analysis studies in the laser cutting has been grown [10] [11]. Even there was various image processing techniques reported in the literatures, this 41 | Page www.ijacsa.thesai.org