  This is the documentation of the tomographic X-ray data of a walnut made
available at http://www.fips.fi/dataset.php . The data can be freely used for
scientific purposes with appropriate references to the data and to this
document in arXiv. The data set consists of (1) the X-ray sinogram of a single
2D slice of the walnut with three different resolutions and (2) 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
data set, the latter serving as a ground truth reconstruction.

Data Analysis, Statistics and Probability;Medical Physics