HAFREE: A Heatmap-Based Anchor-Free Detector for Apple Defect Detection

Accurate inspection of subtle defects on apple surfaces is necessary in agricultural engineering. However, existing methods often rely on expensive equipment and encounter difficulty in detecting small defect areas effectively. To address this challenge, we introduce the Subtle Surface Defects in Ap...

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Main Authors: Nguyen Bui Ngoc Han, Ju-Hwan Lee, Dang Thanh Vu, Iqbal Murtza, Hyoung-Gook Kim, Jin-Young Kim
Format: Article
Language:English
Published: IEEE 2024-01-01
Series:IEEE Access
Subjects:
Online Access:https://ieeexplore.ieee.org/document/10776948/
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author Nguyen Bui Ngoc Han
Ju-Hwan Lee
Dang Thanh Vu
Iqbal Murtza
Hyoung-Gook Kim
Jin-Young Kim
author_facet Nguyen Bui Ngoc Han
Ju-Hwan Lee
Dang Thanh Vu
Iqbal Murtza
Hyoung-Gook Kim
Jin-Young Kim
author_sort Nguyen Bui Ngoc Han
collection DOAJ
description Accurate inspection of subtle defects on apple surfaces is necessary in agricultural engineering. However, existing methods often rely on expensive equipment and encounter difficulty in detecting small defect areas effectively. To address this challenge, we introduce the Subtle Surface Defects in Apples (SSDA) dataset, a custom dataset specifically collected and annotated for two defect types: scratches and pest damage. For benchmarking, we propose a heatmap-based anchor-free (HAFREE) detector, a novel end-to-end object detection architecture designed to localize subtle defects on apple surfaces. Unlike prior methods that rely on anchor boxes, HAFREE employs a heatmap-based approach to represent defects as keypoints using two-dimensional Gaussian heatmaps. We introduce a multiscale feature fusion block, targeting small objects by incorporating local and global contextual information. To mitigate overfitting, we also implement a patch training strategy incorporating full images and cropped patches during training as a regularizer. The proposed method achieves a mAP50 of 50.05% on the SSDA dataset, outperforming one- and two-stage anchor-based detectors and previous anchor-free approaches. Code is available at: <uri>https://github.com/nbngochan/HAFREE</uri>.
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publishDate 2024-01-01
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spelling doaj-art-8abd5172e9ec4296b261c076a0a5dd4b2025-08-20T01:54:38ZengIEEEIEEE Access2169-35362024-01-011218279918281310.1109/ACCESS.2024.350439910776948HAFREE: A Heatmap-Based Anchor-Free Detector for Apple Defect DetectionNguyen Bui Ngoc Han0https://orcid.org/0009-0007-7462-662XJu-Hwan Lee1https://orcid.org/0000-0002-1553-9637Dang Thanh Vu2https://orcid.org/0000-0003-0743-8251Iqbal Murtza3https://orcid.org/0000-0001-7541-8581Hyoung-Gook Kim4https://orcid.org/0000-0002-1518-4100Jin-Young Kim5https://orcid.org/0000-0002-4896-8980Department of Electronic Convergence Engineering, Kwangwoon University, Seoul, South KoreaDepartment of Intelligent Electronics and Computer Engineering, Chonnam National University, Gwangju, South KoreaResearch Center, AISeed Inc., Gwangju, South KoreaDepartment of Intelligent Electronics and Computer Engineering, Chonnam National University, Gwangju, South KoreaDepartment of Electronic Convergence Engineering, Kwangwoon University, Seoul, South KoreaDepartment of Electronic Convergence Engineering, Kwangwoon University, Seoul, South KoreaAccurate inspection of subtle defects on apple surfaces is necessary in agricultural engineering. However, existing methods often rely on expensive equipment and encounter difficulty in detecting small defect areas effectively. To address this challenge, we introduce the Subtle Surface Defects in Apples (SSDA) dataset, a custom dataset specifically collected and annotated for two defect types: scratches and pest damage. For benchmarking, we propose a heatmap-based anchor-free (HAFREE) detector, a novel end-to-end object detection architecture designed to localize subtle defects on apple surfaces. Unlike prior methods that rely on anchor boxes, HAFREE employs a heatmap-based approach to represent defects as keypoints using two-dimensional Gaussian heatmaps. We introduce a multiscale feature fusion block, targeting small objects by incorporating local and global contextual information. To mitigate overfitting, we also implement a patch training strategy incorporating full images and cropped patches during training as a regularizer. The proposed method achieves a mAP50 of 50.05% on the SSDA dataset, outperforming one- and two-stage anchor-based detectors and previous anchor-free approaches. Code is available at: <uri>https://github.com/nbngochan/HAFREE</uri>.https://ieeexplore.ieee.org/document/10776948/Anchor-free detectordeep learningfruit datasetGaussian mapobject detectionsubtle defect detection
spellingShingle Nguyen Bui Ngoc Han
Ju-Hwan Lee
Dang Thanh Vu
Iqbal Murtza
Hyoung-Gook Kim
Jin-Young Kim
HAFREE: A Heatmap-Based Anchor-Free Detector for Apple Defect Detection
IEEE Access
Anchor-free detector
deep learning
fruit dataset
Gaussian map
object detection
subtle defect detection
title HAFREE: A Heatmap-Based Anchor-Free Detector for Apple Defect Detection
title_full HAFREE: A Heatmap-Based Anchor-Free Detector for Apple Defect Detection
title_fullStr HAFREE: A Heatmap-Based Anchor-Free Detector for Apple Defect Detection
title_full_unstemmed HAFREE: A Heatmap-Based Anchor-Free Detector for Apple Defect Detection
title_short HAFREE: A Heatmap-Based Anchor-Free Detector for Apple Defect Detection
title_sort hafree a heatmap based anchor free detector for apple defect detection
topic Anchor-free detector
deep learning
fruit dataset
Gaussian map
object detection
subtle defect detection
url https://ieeexplore.ieee.org/document/10776948/
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