摘要：本文提出了一種基于離散余弦變換（DCT）域圖像水印算法。
圖像水印算法有兩個階段：特征嵌入和特征檢測。第一階段，它將一個標識符號嵌入進圖像。第二階段是被公認（已知）的。該算法有兩個處理步驟。第一步無疑是選擇像素區(qū)塊并使用參數(shù)進行設置，而第二個步驟是將DCT系數(shù)強制的嵌入在選定的區(qū)塊內。兩種不同的參數(shù)規(guī)則表明修改DCT參數(shù)系數(shù)出現(xiàn)頻率的重要性。第一種方法是將DCT規(guī)則嵌入到選定的線性約束內，而第二種方法則是按照所給予的特定參數(shù)進行循環(huán)檢測。上述所提到的水印算法是不能在JGEG壓縮和過濾條件下使用的。
Abstract: In this paper we propose an image watermarking algorithm based on constraints in the Discrete Cosine Transform (DCT) domain.
An image watermarking algorithm has two stages: signature casting (embedding) and signature detection. In the first stage it embeds an identifying label in the image. This is recognized in the second stage. The proposed algorithm has two processing steps. In the first step certain pixel blocks are selected using a set of parameters while in the second step a DCT coefficient constraint is embedded in the selected blocks. Two different constraint rules are suggested for the parametric modification of the DCT frequency coefficients. The first one embeds a linear constraint among certain selected DCT coefficients and the second defines circular detection regions according to the given parameters. The watermarks cast by the proposed algorithm