Unsupervised Decomposition of Color Document Images by Projecting Colors to a Spherical Surface

A decomposition method for color document images is proposed in this paper. A two dimensional feature surface is constructed from the input color image, and then a novel and unsupervised method based on contour lines is proposed to segment the surface. In detail, colors of the image pixels are firstly projected to a spherical surface whose center is the background color. The projection is used to transform the observed colors to the corresponding 'ideal' foreground colors. Then the spherical surface is segmented into several non-overlapped regions, and each region corresponds to an individual layer of the input color document image. Finally, the image pixels are projected to the spherical surface and classified to the corresponding layers.