A New Method for Copyright and Integrity Protection for Bitmap Images by Removable Visible Watermarks and Irremovable Invisible Watermarks*

Nowadays, digital images may be copied or tampered easily, resulting possibly in unauthorized uses or modifications of them. A new method of embedding both removable visible watermarks and irremovable invisible watermarks in BMP images is proposed to solve this problem, which is based on the use of a human visual model and the least-significant-bit replacement technique. The method can be employed to embed visible watermarks in images for direct claim of image ownership. The visible watermark is specially designed and may be removed, whenever necessary, to restore the original image, so that only the watermarked image need be kept to save storage space. On the other hand, irremovable invisible watermarks may also be embedded behind images, which may be extracted to prove the copyright of the images. Furthermore, by checking the existence of watermark signals in images, any tempering of image blocks can be detected and so the image integrity can be verified. Good experimental results prove the feasibility of the proposed method. * This work was supported partially by the Ministry of Education under the Project of Excellency No. 90-E-FA04-1-4.