外文翻譯及文獻(xiàn)--基于子帶離散余弦變換dct應(yīng)用于圖像水印的技術(shù)-文庫吧資料
2025-05-22 05:23本頁面
【正文】 tic. These algorithms are either in image intensity domain or in frequency domain. In the middle range DCT frequency coefficients from the 8*8 pixel blocks are used for embedding a constraint. In the signature is embedded in the DCT coefficients obtained after applying the DCT transform in the entire image. An watermarking algorithm has two stages: watermarking casting and detection. By means of watermark casting a specific code assigned to the owner is embedded in the image. In the detection stage the algorithm identifies the given code. Signal detection theory is a wellestablished field with many applications. A watermarked image can be processed by means of various image transformations and processing algorithms which may be able to destroy, intentionally or not, the digital watermark. Image pression is the most likely transformation that an image may undergo. The standard still image pression algorithm is JPEG. JPEG is based on the minimization of the energy in the Discrete Cosine Transform (DCT) domain. In the case of lossy pression, the image suffers information loss in the high frequency domain. In the proposed watermark casting algorithm from, the image is partitioned in 8*8 pixel blocks similar to the JPEG algorithm. The watermarking algorithm consists of two steps. The first step selects certain blocks according to a Gaussian work. In the selected blocks we modify DCT coefficients such that they fulfill a given constraint. The parameters of the Gaussian functions and of the imposed constraints on the DCT coefficients make up the watermark code. In the detection stage we first check for the DCT constraints and afterwards for the respective block location. In Section 2 we propose a technique for choosing block sites. The DCT constraint embedding step is explained in Section 3. The detection stage is presented in Section 4. This analysis is necessary in order to determine the suitable watermark parameters such that each watermark is distinctly identified from all the others. The simulation results for applying the proposed algorithms in gray level and color images are provided in Section 6. In Section 7 the conclusions of the present study are drawn. 。在檢測階段我們首先檢測 DCT 參數(shù)，然后檢測各自的區(qū)塊的位置來確定是否被篡改。在選定的塊中，我們通過修改 DCT 參數(shù)來使其強(qiáng)制完成某一給予的約束。該水印算法包括兩個步驟。受損壓縮，即使圖像的信息遭受損失的壓縮方法是在高頻域上發(fā)生的。標(biāo)準(zhǔn)的靜態(tài)圖像
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