This letter reports that a novel analysis system has been developed to determine lattice distortion in silicon single crystals from plane-wave X-ray topographs taken using synchrotron radiation. The system analyzes the topographs recorded on the imaging plate and gives the distortion as local variations in spacing and orientation of the lattice plane. Line analysis and mapping of the distortion in any position on the topograph can be easily performed in the system due to the overall digitization by the imaging plate.