Edge detection is widely used for image processing to improve the detection and classification of objects, segmentation, and extraction of other features. Satellite images are rich in information about objects with different color intensity and have a large amount of noise, so it is difficult to achieve recognition, classification, and feature extraction of small objects through traditional edge detection algorithms. The colors in satellite images suffer from a large amount of overlap due to areas or weather conditions that generate a lot of noise. Edge detection provides detailed information about objects in an image by reducing unnecessary feature information. Edge detection in color images is more challenging than edge detection in gray-level images. This paper proposes a method for the edge detection of color images using Clifford algebra and its sub-algebra, quaternions. Quaternion-based Fourier transform is used to process red, green and blue (RGB) images separately in the vector field. A 3×3 quaternion mask is developed to filter out frequencies of the image in multiple directions and only provides details about the edges. The algorithm works on three channels individually; the output is then processed through quaternion Fourier transform (QFT) and inverse QFT with a 3×3 mask to filter high frequencies. The proposed algorithm is compared with traditional edge detection algorithms using a satellite image dataset that has different types of objects and detailed information. Results are validated through entropy, structure similarity, and noise error to prove that our proposed algorithm provides satisfactory performance on different remote sensed images.

Skull sex estimation is one of the hot research topics in forensic anthropology, and has important research value in the fields of criminal investigation, archeology, anthropology, and so on. Sex estimation of skull is crucial in forensic investigations, whether in legal situations that involve living people or to identify mortal remains. The aim of this study is to establish a skull‐based sex estimation model in Chinese population, providing a scientific reference for the practical application of forensic medicine and anthropology. We take the superior orbital margin and frontal bone of the skull as the research object and proposed a technology of objective sex estimation of the skull using wavelet transform and Fourier transform. Firstly, the supraorbital margin and frontal bone were quantified by wavelet transform and Fourier transform, and then the extracted features were classified by SVM, and the model was tested. The experimental results show that the accuracy rate of male and female sex discrimination is 90.9% and 94.4%, respectively, which is higher than that of morphological and measurement methods. Compared with the traditional methods, the method has more theoretical basis and objectivity, and the correct rate is higher.

We present a simple pairwise matching method for 3D fragment reassembly that uses boundary curves and concave-convex patches to accelerate and optimize the matching. Given the boundary curves of two fracture surfaces that completely or partially coincide, we can quickly exclude the fracture surface pairs with low boundary curve similarities, which can substantially reduce the computational cost of the subsequent patch matching, where we extract and delineate concave-convex patches of the selected fracture surfaces. A modified iterative closest point algorithm is applied on these concave-convex patches to refine the alignment. Finally, we determine the matched 3D fragments according to the overlap ratio of their fracture surfaces. The results of experiments on real-world examples demonstrate that our proposed algorithm is both accurate and efficient.

Nuclear DNA C-values are the basic data of species and used in a strikingly wide range of biological fields. Genome size of the most species belonging to the three families Nulembonaceae, Cabombaceae and Nym-phaeaceae in Nymphaeales were not assessed, especially none of the species in Cabombaceae was reported so far. In present research, flow cytometry was used to assess the genome size of 12 species belonging to the three families in Nymphaeales and a standard squash technique to count the chromosome numbers of the tested materials. In the tested different species, 2C nuclear DNA contents ranged from 1.55 to 8.11 pg, which is more than fivefold variation. And chromosome numbers varied from 2n=16 to 2n=72. Differences between the species or among populations within a species were also recorded by statistical analysis. The tested species are all small genomes except two species of Victoria. The ploidies did not matched with their DNA contents very well in Nymphaea. Significant differences were found between the species of Nymphaea, between those of Victoria and among wild populations of Nelumbo nicifera., while no obvious differences were found between the species of Nelumbo and among the cultivars of Euryale ferox as well as among those of Brasenia schreberi, respectively.