cc-by-4.0Hämäläinen, KeijoHarhanen, LauriKallonen, AkiKujanpää, AnttiNiemi, EsaSiltanen, Samuli2025-03-242015-02-112015-02-11https://hydatakatalogi-test-24.it.helsinki.fi/handle/123456789/9026This is an open-access dataset of tomographic X-ray data of a walnut. The dataset consists of the X-ray sinogram of a single 2D slice of the walnut with three different resolutions and the corresponding measurement matrices modeling the linear operation of the X-ray transform. Each of these sinograms was obtained from a measured 120-projection fan-beam sinogram by down-sampling and taking logarithms. The original (measured) sinogram is also provided in its original form and resolution. In addition, a larger set of 1200 projections of the same walnut was measured and a high-resolution filtered back-projection reconstruction was computed from this data; both the sinogram and the FBP reconstruction are included in the dataset, the latter serving as a ground truth reconstruction. Documentation of the dataset is available at arxiv.org/abs/1502.04064. See also www.fips.fi/dataset.php.OpenX-rayRadon transforminverse problemdataset