###### Abstract
In particular, pulsed phase thermography (PPT) and principal component thermography (PCT) were used as post-processing techniques. Ultrasonic C-scan and continuous wave terahertz imaging were also carried out on the mineral fiber laminates for comparative purposes. An analytical comparison of different methods was given [24]. The main aim of the work written by [PERSON] and [PERSON] consisted in the analysis of time changes of features extracted from thermal images using the multivariate approach. The paper showed that if the principal component analysis (PCA), belonging to multivariate methods, is applied for quality control based on infrared images, then the minimum testing times can be estimated. Inparticular, a detailed temporal analysis for an exemplary production line has been carried out, and future perspectives were given, too [25]. [PERSON] described a proposal for the qualitative assessment of the condition of supercapacitors based on thermographic measurements. Necessary conditions to minimize the influence of disturbing factors on the performance of thermal imaging were also indicated. All the tests were conducted in conjunction with the classical methods based on capacitance (\(C\)) and equivalent series resistance (\(ESR\)) measurements; some selected results present the observed changes occurring in both. Limitations of the proposed assessment method, as well as the suggestions for its future development, were also described [26]. [PERSON] described the advantages and enhanced accuracy that thermography provided to high temperature mechanical testing. In particular, this work demonstrated the superior visibility of test temperatures previously unobtainable by conventional thermocouples or even more modern pyrometers that thermography can deliver. The speed and accuracy of thermal profiling, thermal gradient measurements and cold/hot spot identification using the technique has increased significantly to the point where temperature can now be controlled by averaging over a specified area. Finally, the increased visibility of specimen temperatures has revealed additional unknown effects described in the paper itself [27]. [PERSON] et al. proposed an improved dual-tree complex wavelet transform (DTCWT) optimized by an improved fruit-fly optimization algorithm (IFOA) and bilateral filter (BF) in order to eliminate the noise of infrared images without reference and noise models. In the experiment, the proposed method is applied to eliminate both addictive noise and multiplicative noise, while the denoising results were compared to other representative methods. Finally, the proposed method was applied as a pre-processing utilization for infrared thermal images in a coal mining working face [28]. In [29], [PERSON] et al. applied pulsed infrared thermography with the aim to provide stratigraphic information in different kinds of cultural heritage artefacts by analyzing the heat diffusion process within the sample after thermal perturbation. Moreover, the integration of such pulsed infrared thermography and three-dimensional shape-recording methods was proposed in order to provide a three-dimensional representation of the thermographic results. Finally, it was underlined how such a technique may be crucial to understand historical, technical and artistic points of view of the art master. [PERSON] focused attention on the induction thermography method useful to localize surface cracks in metals. It was found that the transformation of the temporal temperature development for each pixel to phase information made not only highly reliable detection of the cracks possible, but also allowed an estimation of its depth. Finite element simulations were carried out to investigate how the phase contrast depends on several parameters. From the results obtained, generalized functions for the dependency of the phase difference on all the listed parameters were derived. They can be used as excellent guidelines to reach the goal of the paper described in the title.