Institutional Repository UIN Sunan Kalijaga YogyakartaRANCANG BANGUN APLIKASI WATER CONTACT ANGLE ANALYZER DENGAN MENGGUNAKAN METODE OTSU THRESHOLDING, CANNY EDGE, HOUGH LINE TRANSFORM DAN CIRCLE FITTING CURVE BERBASIS PYTHONNIM.: 22106020003Trengginas Wibowo ShidiqauthorAn automated Water Contact Angle (WCA) Analyzer application based on computer vision was developed using Python to automatically measure water contact angle. The application integrates Image Preprocessing, image segmentation using Otsu Thresholding, baseline detection using Canny Edge and Hough Line Transform, droplet profile reconstruction using Circle Fitting Curve, and automatic contact angle calculation and wettability classification, accessible through a PyQt5-based graphical user interface. Validation was performed by comparing the results with ImageJ (LB-ADSA plugin) using 120 microscopic images from a Dino-Lite microscope (220x magnification), covering 24 angle values from hydrophilic and hydrophobic samples. The results show an average Mean Absolute Error (MAE) of 0.74°, an accuracy of 99.40%, and a precision of 99.74% relative to ImageJ, with a Root Mean Squared Error (RMSE) of 1.7249°, indicating that the deviation was dominated by systematic error caused by the geometric assumption of Circle Fitting at high contact angles (>120°). The application also successfully classified all samples into the correct wettability category with 100% accuracy. These results demonstrate that the developed WCA Analyzer application provides accurate, precise, and consistent contact angle measurements, offering a promising, objective, automated, and affordable alternative for surface wettability characterization.530 Fisika2026-08-10UIN SUNAN KALIJAGA YOGYAKARTA;FAKULTAS SAINS DAN TEKNOLOGIThesis

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