Skripsi
PERBAIKAN KUALITAS CITRA DENGAN NONLINEAR ACTIVATION FREE NETWORK UNTUK KLASIFIKASI PENYAKIT ALZHEIMER PADA CITRA MRI
Alzheimer’s disease is a progressive neurodegenerative disorder that is the leading cause of dementia. The use of Magnetic Resonance Imaging (MRI) in ResNet18-based classification can be hindered by the presence of noise, particularly Rician noise, which obscures important structural details and reduces model performance. This study employs the Nonlinear Activation Free Network (NAFNet) to improve MRI image quality and evaluate classification performance across three data conditions, namely raw images, noisy images (generated by synthetic noise), and enhanced images. Image quality is evaluated using PSNR and SSIM, while classification performance is measured using accuracy and macro F1-score to account for class imbalance. The results show that noise significantly reduces performance from an accuracy of 98.34% and macro F1-score of 98.87% on raw images to 79.11% and 76.82% on noisy images. After enhancement using NAFNet, image quality improved, with PSNR increasing from 25.91 dB to 34.57 dB and SSIM from 0.5361 to 0.9626, while classification performance improved to an accuracy of 96.78% and macro F1-score of 97.61%. These results demonstrate that image enhancement improves the model’s robustness against noise degradation in MRI images.
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