基于块分类和DCT域的图像水印算法-----外文翻译.doc

毕业论文（设计） 外文翻译 基于块分类摘要：本文提出了一种基离散余弦变换（DCT）域图像水印算法。特征检测第一阶段，它嵌入该算法有两个处理步骤。为了避免未经授权图片或其他多媒体这些算法，图像强度域域特征检测信号检测理论是一种离散余弦变换（DCT）域高斯网 Image watermarking using block site selection and DCT domain constraints 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 are resistant to JPEG compression and filtering. 1. Introduction Digital watermarks in the general context of TV broadcasting and cryptology were discussed in. To avoid the unauthorized distribution of images or other multimedia property, various solutions have been proposed. Most of them make unobservable modifications to images, that can be detected afterwards . Such image changes are called watermarks. The watermark should not alter visibly the image and it should be robust to alterations which may be caused by various image processing techniques. Algorithms proposed for watermarking have been reported in various papers. They are either stochastic or deterministic. 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 coefficient