Robust watermarking of fingerprint images

This paper introduces two spatial methods in order to embed watermark data into "ngerprint images, without corrupting their features. The "rst method inserts watermark data after feature extraction, thus preventing watermarking of regions used for "ngerprint classi"cation. The method utilizes an image adaptive strength adjustment technique which results in watermarks with low visibility. The second method introduces a feature adaptive watermarking technique for "ngerprints, thus applicable before feature extraction. For both of the methods, decoding does not require original "ngerprint image. Unlike most of the published spatial watermarking methods, the proposed methods provide high decoding accuracy for "ngerprint images. High data hiding and decoding performance for color images is also observed. ? 2002 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.