Colored Rubber Stamp Removal from Document Images

Abstract

Rubber stamps on document pages often overlap and obscure the text very badly, thereby impairing its readability and deteriorating the performance of an optical character recognition system. Removal of rubber stamps from a document image is, therefore, essential for successfully converting a document image into an editable electronic form. We propose here an effective technique for rubber stamp removal from scanned document images. It is based on the novel idea of a single feature obtained by projecting the pixel colors of the image foreground along the eigenvector corresponding to the first principal component in HSV color space. Otsu’s adaptive thresholding is used to segment out the stamp impressions from the text by exploiting the discriminative power of the aforesaid feature. Experimentation and subjective evaluation on a variety of scanned document images demonstrate the strength and effectiveness of the proposed technique.