Publications by authors named "Yoni De Witte"
In conventional X-ray microtomography (μCT), the three-dimensional (3D) distribution of the attenuation coefficient of X-rays is measured and reconstructed in a 3D volume. As spatial resolution increases, the refraction of X-rays becomes a significant phenomenon in the imaging process. Although this so-called phase contrast was initially a cumbersome feature in lab-based μCT, special phase retrieval algorithms were developed to exploit these effects.
View Article and Find Full Text PDFThree-dimensional (3D) analysis is an essential tool to obtain quantitative results from 3D datasets. Considerable progress has been made in 3D imaging techniques, resulting in a growing need for more flexible, complete analysis packages containing advanced algorithms. At the Centre for X-ray Tomography of the Ghent University (UGCT), research is being done on the improvement of both hardware and software for high-resolution X-ray computed tomography (CT).
View Article and Find Full Text PDFBackground And Aims: Density is a crucial variable in forest and wood science and is evaluated by a multitude of methods. Direct gravimetric methods are mostly destructive and time-consuming. Therefore, faster and semi- to non-destructive indirect methods have been developed.
View Article and Find Full Text PDFA multiresolution approach to iterative reconstruction algorithms in X-ray computed tomography.
IEEE Trans Image Process
September 2010
In computed tomography, the application of iterative reconstruction methods in practical situations is impeded by their high computational demands. Especially in high resolution X-ray computed tomography, where reconstruction volumes contain a high number of volume elements (several giga voxels), this computational burden prevents their actual breakthrough. Besides the large amount of calculations, iterative algorithms require the entire volume to be kept in memory during reconstruction, which quickly becomes cumbersome for large data sets.
View Article and Find Full Text PDFMechanical stress, fracture risk and beak evolution in Darwin's ground finches (Geospiza).
Philos Trans R Soc Lond B Biol Sci
April 2010
Article Synopsis
- Darwin's finches evolved from a common ancestor into 14 species, each with unique beak forms adapted to different food resources, primarily through natural selection influenced by food type and competition.
- Research using finite-element modeling indicates that finch beak size and shape have evolved primarily to avoid fractures rather than just to crack seeds, suggesting mechanical stress plays a crucial role in beak evolution.
- The study found that deeper and wider beaks are more effective at reducing stress during seed cracking, minimizing the risk of beak failure, which explains the strong natural selection for these traits among Darwin's finches.
Unlabelled: Sandstones are used in many contemporary and historical buildings. With time, these buildings become dark and a surface crust is formed. Generally, these crusts mainly consist of minerals of which the constituents were mobilised from the interior of the stone, and material from the surrounding environment like air pollutants and dust.
View Article and Find Full Text PDFBronnikov-aided correction for x-ray computed tomography.
J Opt Soc Am A Opt Image Sci Vis
April 2009
Article Synopsis
- When scanning low-absorbing samples with x-ray computed tomography, projection images can include both absorption and phase contrast, leading to artifacts in the reconstructed images.
- A new correction method, called Bronnikov-aided correction (BAC), is introduced to remove unwanted phase signals from these mixed projection images, allowing for clearer reconstructions.
- BAC has been tested on biological and pharmaceutical samples, demonstrating improved results compared to traditional reconstruction techniques with minimal extra effort.