Multimedia Security
1. Control access such that only the right people can access to the multimedia content
2. Prevent illegal duplications
3. Authenticate the multimedia content are from the true sender (prevent impersonation and faked media distribution)
4. Images (Photo), Graphics, audio (music and song) and video can be protected by digital watermark
5. Watermark system makes use of the fundamental property of the human visual system/human auditory system – a visual (or audio) stimulus is less noticeable if superimposed over another large stimulus. Thus digital watermark make use of such properties in human perception and watermark can be added to media by noise masking/distortion masking techniques.
A. Visible Watermark
Visible watermark and copyright information can be added directly to the image.
多媒體安全
1. 通過只有能正確輸入密碼的人才能獲得進入多媒體內容的權利來控制通道；
2. 防止非法復制；
3. 證實多媒體內容是來自真實的發(fā)令者(防止假借和偽造的媒介發(fā)行)；
4. 數(shù)字式水印可以保護圖象(相片), 圖表, 音像(音樂和歌曲)以及錄影；
5. 水印系統(tǒng)利用人類視覺系統(tǒng)及人類聽覺系統(tǒng)的特性-如果附加的超過其他的大激勵，則視覺（或聽覺）激勵就顯得不那么明顯了。數(shù)字式水印正是利用了這種人類感覺特性，同時水印可以通過噪聲掩蔽以及變形掩蔽技術加到媒介中。
可視水印