用近红外高光谱成像提升食品质量分析,改进了深度学习与传统方法的结合方式。
Near-Infrared Hyperspectral Imaging Applications in Food Analysis -- Improving Algorithms and Methodologies
- 用带光谱卷积层的2D CNN增强化学参数预测性能
- 联合时空分析比单独空间或光谱分析更准确,尤其适合化学物理信息相关的检测
- 开发两个开源工具包,加速PLS建模与交叉验证
本论文研究近红外高光谱成像(NIR-HSI)在食品质量分析中的应用,通过四项研究验证五个假设。在多数分析中,结合时空信息的卷积神经网络(CNN)优于仅使用空间特征的CNN或基于偏最小二乘法(PLS)的光谱分析,尤其当化学与物理视觉信息相关时。采用2D CNN并加入初始光谱卷积层后,其预测性能显著提升,学习到类似领域专家的预处理效果。然而,对于样本平均化学含量的分析,基于PLS的方法表现相当,仍为推荐方案。由于难以获取空间分辨的参考值,脂肪分布图生成中使用了整体平均值作为参考;此时PLS产生非平滑地图且像素预测超出0-100%范围,而改进的2D CNN则有效避免上述问题。最后一项研究尝试通过分析大麦的近红外光谱、RGB图像和NIR-HSI图像来预测发芽能力,但因数据集发芽率过低导致结果不明确。此外,本研究还开发了两个开源Python工具包:一个用于快速构建PLS模型,另一个基于新算法实现超快的PLS及其他经典机器学习模型的交叉验证。
原文摘要 · Abstract (English)
This thesis investigates the application of near-infrared hyperspectral imaging (NIR-HSI) for food quality analysis. The investigation is conducted through four studies operating with five research hypotheses. For several analyses, the studies compare models based on convolutional neural networks (CNNs) and partial least squares (PLS). Generally, joint spatio-spectral analysis with CNNs outperforms spatial analysis with CNNs and spectral analysis with PLS when modeling parameters where chemical and physical visual information are relevant. When modeling chemical parameters with a 2-dimensional (2D) CNN, augmenting the CNN with an initial layer dedicated to performing spectral convolution enhances its predictive performance by learning a spectral preprocessing similar to that applied by domain experts. Still, PLS-based spectral modeling performs equally well for analysis of the mean content of chemical parameters in samples and is the recommended approach. Modeling the spatial distribution of chemical parameters with NIR-HSI is limited by the ability to obtain spatially resolved reference values. Therefore, a study used bulk mean references for chemical map generation of fat content in pork bellies. A PLS-based approach gave non-smooth chemical maps and pixel-wise predictions outside the range of 0-100\%. Conversely, a 2D CNN augmented with a spectral convolution layer mitigated all issues arising with PLS. The final study attempted to model barley's germinative capacity by analyzing NIR spectra, RGB images, and NIR-HSI images. However, the results were inconclusive due to the dataset's low degree of germination. Additionally, this thesis has led to the development of two open-sourced Python packages. The first facilitates fast PLS-based modeling, while the second facilitates very fast cross-validation of PLS and other classical machine learning models with a new algorithm.
Thank you to arXiv for use of its open access interoperability. PaperDance 不是 arXiv 官方产品;中文卡片由大模型生成,请以原文为准。