Tomographic microscopy using synchrotron radiation provides high-resolution structure details on the scale of
microns. The field of view (FOV) of the microscopy system, however, is usually limited by the detector size.
For example, a typical CCD camera used for data acquisition is of size 2048 by 2048. In many cases this CCD
camera is not large enough to provide complete information required for accurate reconstruction, and the local
tomography problem hereby arises. On the other hand, the huge dataset generated by tomographic microscopy
asks for a highly efficient solution with no a priori information necessary. A new padding scheme is therefore
proposed for the local tomography issue. It first pads the projection data using the boundary value inside the
FOV, which is specified by the detector size, followed by a zero-value padding to 1.5 times the FOV length.
The boundary-value padding removes the energy deposition and cupping artifact in reconstruction results from
local tomography, while the zero-value padding reduces the drift of the intensity values caused by fully boundary
padding. The combination of two padding schemes keeps advantages of fully zero-value padding and fully
boundary-value padding, while avoiding their disadvantages. Quantitative analysis using synthetic data shows
that the proposed method outperforms fully zero-value padding and fully boundary-value padding in terms of
accuracy and ease for post processing. Experimental results for real data are also provided to demonstrate the
effectiveness of the proposed method.