High dynamic range reflectance transformation imaging: an adaptive multi-light approach for visual surface quality assessment

Reflectance Transformation Imaging as a Tool for Computer-Aided Visual Inspection

“…The principle of this technique is illustrated in Figure 1, where PTM, HSH, and DMD are RTI reconstruction models and stand for Polynomial Texture Mappings, Hemispherical Harmonics, and Discrete Modal Decomposition, respectively. Many new RTI acquisition modalities have recently been developed, including multispectral approaches [34,35], approaches to measure the complete luminance dynamic (HD-RTI, [36][37][38]) self-adaptive approaches to determine the relevant lighting directions (NBLP-RTI, [39]), and even robot-based RTI systems [40]. Within the framework of this research, we focus on the RTI acquisition parameters associated with the conventional approach.…”

HD-RTI: An adaptive multi-light imaging approach for the quality assessment of manufactured surfaces

“…These nonmeasured pixels make it impossible to robustly discriminate the anomalies and evaluate their criticality in terms of perception. The work presented in this article aims to answer this issue by proposing an adaptive coupling of HDR and RTI imaging techniques [27].…”

Next Best Light Position: A self configuring approach for the Reflectance Transformation Imaging acquisition process

“…However continuous acquisition from every possible light direction is not practically feasible and the size of the data will be too big to handle. Multi-modal acquisition like multi-spectral [10], high dynamic range RTI [11], UV are the growing trends in RTI where enormous data is generated during acquisition and hence continuous acquisition poses numerical practical problems. Besides, cultural heritage conservation, RTI is oftentimes applied in industries too as a tool for engineering failure analysis [12], [13].…”