The images are one of the most used kinds of the information in modern information company. Therefore actual problems is the organization of protection from unauthorized access and usage. An important characteristic of the image is the presence of contours in the image. The task of contour selection requires the use of operations on adjacent elements that are sensitive to change and suppress areas of constant levels of brightness, that is, contours are those areas where changes occur, becoming light, while other parts of the image remain dark. Mathematically, the ideal outline is to break the spatial function of the brightness levels in the image plane. Therefore, contour selection means finding the most dramatic changes, that is, the maxima of the gradient vector module. This is one of the reasons that the contours remain in the image when encrypted in the RSA system, since the encryption here is based on a modular elevation of some natural number. At the same time, on the contour and on the neighboring contours of the peak villages, the elevation of the brightness value gives an even bigger gap.
Problem protect from unauthorized access is by more composite in matching with a problem protect from usage. Basis for organization of protection is the interpretation of the image as stochastic signal. It stipulates carry of methods of encoding of signals on a case of the images. But the images are a specific signal, which one in possesses, is padding to representative selfless creativeness, also by visual selfless creativeness. Therefore to methods of encoding, in case of their usage concerning the images, one more requirement – full noise of the coded image is put forward. It is necessary to make to impossible usage of methods of visual image processing. The algorithm RSA is one of the most used production specifications of encoding of signals. In attitude of the images there are some problems of its encoding, the contours on the coded image are in particular saved. Therefore actual problem is the mining of modification to a method RSA such, that: to supply stability to decoding; to supply full noise of the images. One of pathes of the solution of this problem is usage of affine transformations.
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