基于子帶離散余弦變換DCT應用于圖像水印的技術已經(jīng)被提出并應用。水印是波在所有選定的含有若干系數(shù)的四個頻帶段的1級分解。應用大量的系數(shù)使每個波段給出了不同的檢測輸出結(jié)果。其結(jié)果是采取平均檢測結(jié)果的所有頻段的值。結(jié)果表明，最終的結(jié)果是優(yōu)于所檢測輸出的每個波段所得的結(jié)果的，從而實現(xiàn)了非常強大的水印方案。
1、導言
數(shù)字媒體技術在當今社會已被大范圍的使用，從而促使其創(chuàng)立知識產(chǎn)權來保護。就其性質(zhì)而言，數(shù)字媒體是能夠100％被完整復制的，因此，必須采取有效的標識系統(tǒng)（是顯而易見的）。這就是水印的由來。水印技術是指將無法被看見的數(shù)據(jù)埋入圖像中，從而確定合法的創(chuàng)建者/擁有者。水印應當具有健全的可以適用于（抵擋）各種各樣的圖像攻擊的技術。任何嘗試從原始圖像刪除所有權信息的方法（被稱為）攻擊。一些常見的攻擊包括過濾，壓縮，直方圖修改，剪裁，旋轉(zhuǎn)和縮小。（水印）主要有兩個嵌入方向，即空間域和變換域。變換域的技術對普通的圖像攻擊技術更敏感，如過濾或JPEG壓縮。
A subband-DCT approach for image watermarking is proposed in this communication. The watermark is casted in a selected number of coefficients of all four bands of a one-level decomposition. A great number of coefficients is being used. Each band gives a different detection output. The result is taken as the average detection result of all bands. It is shown that the final result is better than the detection output of each individual band, thus leading to a very robust watermarking scheme.
1. INTRODUCTION
The great spread of digital media in nowadays, has urged for the protection of the intellectual property rights of the creators. By their nature, digital media are 100% reliably copied, so the need for an effective marking system is obvious. This is where watermarking comes in. Watermarking