METHOD AND APPARATUS FOR INSERTING A REMOVABLE VISIBLE WATERMARK IN AN IMAGE AND METHOD AND APPARATUS FOR REMOVING SUCH WATERMARKS

摘要

A method of watermarking an image (lo). A visible watermark (T) is inserted (23) in the image (I0) to obtain a visibly watermarked image (lv). Information (22) allowing removal of the visible watermark (T) is protected (24) to obtain protected information (26) that is inserted (27) as an invisible watermark in the visibly watermarked image (lv) to obtain a visibly and invisibly watermarked image (lVι). The information (22) allowing removal of the visible watermark may be image values of the pixels to be covered by the visible watermark and, possibly, the position and size of the visible watermark, in which case these values are first memorised. The visible watermark may be opaque. Also provided are an apparatus for inserting the watermarks, a method for removing the visible watermark, essentially by performing the method 'in a mirror', and an apparatus for removing the visible watermark.