Nonlinear shape restoration for document images

Previous researches on nonlinear shape restoration are based on the assumptions that the original shapes and distortions of the images have known formulations under certain conditions. The main contribution of this research is the development of a new restoration algorithm, called Multi-Steps Restoration. The algorithm is based on a linear interpolation theory that is able to detect and restore nonlinear shape distortions in any irregular quadrilateral-shaped patterns. The main idea of the algorithm is the use of two-dimensional spline functions in bicubic, biquadratic, and/or bilinear models to approximate the three-dimensional nonlinear distortion curves. The performance of the approach shown by experiment is promising