Building of Informatics, Technology and Science
Vol 8 No 2 (2026): September 2026

Optimizing CNN Architecture Selection For Small-Scale Imbalanced Chili Leaf Disease Classification

Muhamad Fery Ardiyansah (Universitas Ngudi Waluyo, Semarang)
Iwan Setiawan Wibisono (Universitas Ngudi Waluyo, Semarang)



Article Info

Publish Date
22 Sep 2026

Abstract

Chili leaf disease reduces yield and farmer income in Indonesia, yet automated diagnosis is typically evaluated using a single architecture or artificially balanced datasets that do not reflect field conditions. This study compared eight CNN architectures (ResNet50, ResNet101, EfficientNetB0, EfficientNetB3, MobileNetV2, MobileNetV3Large, VGG16, and DenseNet121) for six-class chili leaf disease classification on an original dataset of 1,847 images, using on-the-fly augmentation only on the training subset. Each architecture was trained with a frozen feature-extraction transfer-learning protocol and class weighting across three random seeds (24 runs total) to assess robustness. MobileNetV3Large achieved the highest mean accuracy (98.80%) and was selected as the final model, reaching 98.92% accuracy, a macro-average F1-score of 98.09%, and a weighted-average F1-score of 98.90%. A Friedman test confirmed that performance differences among the eight architectures were statistically significant ( = 19.432, = 0.0069), with a Kendall's W of 0.9253 indicating strong ranking agreement across seeds. Grad-CAM visualization showed that the final model's predictions were consistently driven by symptomatic leaf regions rather than background artifacts. These results indicate that a lightweight, lower-parameter architecture can match or exceed deeper models under frozen feature extraction, offering a favorable performance-to-size trade-off for agricultural extension services. This study contributes a statistically validated benchmarking protocol enabling fair comparison across CNN design philosophies on a single, non-synthetically-balanced dataset, a setting most prior chili leaf disease studies have not provided.

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Journal Info

Abbrev

bits

Publisher

Subject

Computer Science & IT

Description

Building of Informatics, Technology and Science (BITS) is an open access media in publishing scientific articles that contain the results of research in information technology and computers. Paper that enters this journal will be checked for plagiarism and peer-rewiew first to maintain its quality. ...