Comparison of color imaging vs. hyperspectral imaging for texture classification

International audienceMany approaches of texture analysis by color or hyperspectral imaging are based on the assumption that the image of a texture can be viewed as a multi-component image, where spatial interactions within and between components are jointly considered (opponent component approach) or not (marginal approach). When color images are coded in multiple color spaces, texture descriptors are based on Multi Color Channel (MCC) representations. By extension, a Multi Spectral Band (MSB) representation can be used to characterize the texture of material surfaces in hyperspectral images. MSB and MCC representations are compared in this paper for texture classification issues. The contribution of each representationis investigated with marginal and/or opponent component strategies. For this purpose, several relevant texture descriptors are considered. Since MSB and MCC representations generate high-dimensional feature spaces, a dimensionality reduction is applied to avoid the curse of dimensionality. Experimental results carried out on three hyperspectral texture databases (HyTexiLa, SpecTex and an original dataset extracted from the Timbers database) show that considering between component interactions in addition to the within ones significantly improves the classification accuracies. The proposed approaches allow also to outperform state of the art hand-designed descriptors and color texture descriptors based on deep learning networks. This study highlights the contribution of hyperspectral imaging compared to color imaging for texture classification purposes but also the advantages of color imaging depending on the considered texture representatio

Compact Hybrid Multi-Color Space Descriptor Using Clustering-Based Feature Selection for Texture Classification

International audienceColor texture classification aims to recognize patterns by the analysis of their colors and their textures. This process requires using descriptors to represent and discriminate the different texture classes. In most traditional approaches, these descriptors are used with a predefined setting of their parameters and computed from images coded in a chosen color space. The prior choice of a color space, a descriptor and its setting suited to a given application is a crucial but difficult problem that strongly impacts the classification results. To overcome this problem, this paper proposes a color texture representation that simultaneously takes into account the properties of several settings from different descriptors computed from images coded in multiple color spaces. Since the number of color texture features generated from this representation is high, a dimensionality reduction scheme by clustering-based sequential feature selection is applied to provide a compact hybrid multi-color space (CHMCS) descriptor. The experimental results carried out on five benchmark color texture databases with five color spaces and manifold settings of two texture descriptors show that combining different configurations always improves the accuracy compared to a predetermined configuration. On average, the CHMCS representation achieves 94.16% accuracy and outperforms deep learning networks and handcrafted color texture descriptors by over 5%, especially when the dataset is small

Enhanced near-ambient temperature energy storage and electrocaloric effect in the lead-free BaTi0.89Sn0.11O3 ceramic synthesized by sol–gel method

International audienceLead-free perovskite materials with high performance have high potential in clean energy storage applications and developments of electrocaloric devices. In this work, we report structural, dielectric, ferroelectric properties, energy storage and electrocaloric effectnear the ambient temperature in barium stannate titanate (BaTi 0.89 Sn 0.11 O 3, BTS 11) ceramic prepared by a sol-gel method. The formation of a single perovskite structure was confirmed using the X-ray diffraction analysis. An average grain size of 18.5µm was found by the mean of the SEM micrograph with a density of 5.91 g/cm 3 .The presence of the multiphase at very near ambient temperature was proved using temperature-dependent micro-Raman measurements and differential scanning calorimetry. The BTS 11 ceramic exhibits a high dielectric constant of 15460and a low dielectric loss (<0.055) with considerable temperature stability. Moreover, a high energy storage density of 122mJ/cm 3 was showed with an efficiency of 79%, and a maximum value of ECE (ΔT) of 0.86 K and finally, an electrocaloric responsivity (ΔT/ΔE) of 0.24 K.mm/kV under the external electricfield of 35 kV/cm near ambient temperature. The enhanced dielectric, ferroelectric and electrocaloric properties in BTS 11 ceramic makes it a great potential candidate for its uses in solid-state cooling technology and high-energy storage applications near ambient temperature

Morphogenesis mechanisms in the hydrothermal growth of lead-free BCZT nanostructured multipods

Due to growing environmental concerns about the toxicity of lead-based piezoelectrics, the replacement of Pb-based materials with homologs with comparable piezoelectric properties but without lead is an emergent task. Since 2009, Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) materials have aroused considerable attention as a replacement due to their excellent dielectric, ferroelectric and piezoelectric properties. Nanostructuring of BCZT can enhance these functionalities even more. Here, templated-growth of BCZT nanostructured multipods with hydrogen zirconate titanate nanowires (HZTO-NWs) was investigated under hydrothermal conditions. The effects of the precursor's concentrations and the hydrothermal reaction time on the morphological formation of BCZT nanostructures were investigated. Besides, composition, structure and phase analysis studies were carried out, and the growth mechanism of BCZT multipods was proposed. It was found that the precursor's concentrations and dwell time in hydrothermal reactions play a critical role in the formation of BCZT multipods, and the desirable BCZT phase was obtained in samples using low barium and calcium concentrations and at a short reaction time. This research has general validity and can be extended to design more complex perovskite oxides