A wavelet approach to extracting contours of document images

In this paper, a new method for extracting contours of document images is proposed. It is a wavelet-based method that consists of three steps. First, by orthogonal wavelet decomposition, a document image is decomposed into a set of wavelet approximation and wavelet details. Next, contour extraction is achieved by applying a wavelet reconstruction technique. In the third step, a multiresolution-contours extraction with respect to an iteration wavelet reconstruction is implemented. A novel combination of multiresolution-contours results in clear contours of the document image. This reconstruction procedure is accompanied by an energy distribution estimation from which wavelet decomposition times can be adaptively controlled. Our method has no redundant operation compared to the scheme of wavelet transform. Therefore, the computational time and memory requirement are less than those by wavelet transform