“Slanted Character Recognition by Subspace Method and Fast Fourier Transform”

It is difficult to recognize characters in a scene image taken by a digital camera since the image usually suffers from geometrical distortions, changing lighting conditions, and so on. We focus on the geometrical distortions. If the transformation is restricted to the affine transformation, the transformation will be the combination of expansion, rotation and slant transformations. Although the size can be adjusted and the rotation angle can be estimated, it is difficult to estimate the slant angle of a character image. In this paper, we propose an algorithm for slanted character recognition. The proposed technique is based on the subspace method and uses fast Fourier transform to calculate the similarity of patterns of various slant angles efficiently. The experimental results show the effectiveness of the proposed method.