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Computer Engineering ›› 2024, Vol. 50 ›› Issue (4): 31-40. doi: 10.19678/j.issn.1000-3428.0069176

• Intelligent Transportation • Previous Articles     Next Articles

Filtering Method for Feature Maps from Convolutional Neural Network for Thermal Imaging Data

Lei ZHANG*(), Guochen SHEN, Dongxiu OU   

  1. College of Transportation Engineering, Tongji University, Shanghai 201804, China
  • Received:2024-01-05 Online:2024-04-15 Published:2024-04-22
  • Contact: Lei ZHANG

用于热成像数据的卷积神经网络特征图筛选方法

张雷*(), 沈国琛, 欧冬秀   

  1. 同济大学交通运输工程学院, 上海 201804
  • 通讯作者: 张雷
  • 基金资助:
    国家重点研发计划(2022YFB4300501); 国家自然科学基金(52172329)

Abstract:

Commonly used visible light image data may fail because of harsh weather or poor light conditions; however, infrared thermal imaging data can effectively complement visible light image data. Existing studies often rely on Domain Adaptation(DA) to apply Convolutional Neural Network(CNN) to visible light image data to process thermal imaging data and overcome the lack of a large annotated training set for infrared data. However, DA methods cannot completely avoid the training process. Researchers have found that the domain-invariant and domain-variant components of an image can be separated in the frequency domain. Inspired by this phenomenon, a filtering method for feature maps from CNN based on Discrete Cosine Transform(DCT) and chi-square independence index is proposed. The domain-invariant and domain-variant components are separated in the frequency domain. By imitating the chi-square independence test, an independence index based on frequency components is proposed to measure the degree of difference in feature maps. According to this index, clustering is used to classify feature maps and identify the class(es) to be maintained or dropped. Thereafter, neural network suitable for thermal imaging data is constructed. The experimental results indicate that this method can determine the latent capabilities of pre-trained CNN for visible light images to extract the features of thermal imaging data without retraining the network. Although the pre-trained network failed to predict the thermal imaging data, the network constructed using the proposed method achieves up to 90% matching between the object and the top five prediction results.

Key words: thermal imaging data, Discrete Cosine Transform(DCT), Domain Adaptation(DA), Convolutional Neural Network(CNN), traffic scene

摘要:

红外热成像数据可以有效辅助可见光图像数据, 弥补其在天气和光照条件上的不足。现有的研究往往借助域适应将基于可见光图像数据训练得到的卷积神经网络用于处理热成像数据, 以弥补热成像数据缺少大量标注训练集的不足, 但是这类方法仍无法避免一定程度的训练。而一些研究者发现, 图像在频域上呈现域不变成分和随域改变成分的分离现象。受这一现象的启发, 提出一种基于离散余弦变换和卡方独立性分数的卷积神经网络特征图筛选方法。利用频域分离域不变成分和随域改变成分, 借鉴卡方独立性检验的思想提出基于频段分量的独立性分数, 用于度量特征图的差异度, 使用聚类将特征图分类, 保留主要包含域不变成分的特征图分支, 得到适用于热成像数据的网络。实验结果表明, 该方法可以充分利用预训练卷积神经网络的潜在预测能力, 且不需要重新训练模型。预训练网络无法预测热成像数据, 而筛选后的网络前5位预测结果与目标相关的比例最高可达90%。

关键词: 热成像数据, 离散余弦变换, 域适应, 卷积神经网络, 交通场景