Digital image compressing, encrypting and encoding combined method

Abstract

The invention discloses a digital image compressing, encrypting and encoding combined method, and belongs to the technical field of image encrypting. The method is achieved on the basis of the JPEG compressing and encoding standard which is most widely applied at present, and the encrypting algorithm based on chaos is integrated with the encoding process; according to the characteristic that DC coefficients and AC coefficients are separately encoded on the basis of the JPEG standard, the DC coefficients and the AC coefficients of an image are separately encrypted; in order to give consideration to both security and compressing efficiency, all the DC coefficients and part of the AC coefficients are encrypted through the method, coefficients at the same positions in all DCT blocks are divided into different groups and are scrambled and diffused within the groups, and damage to differential encoding and run length encoding in the encrypting process is reduced as much as possible; scrambling and diffusing are achieved on the basis of logistic chaotic mapping and Chebyshev chaotic mapping respectively. The experiments prove that the method has high data compressing capacity while providing effective image data security protection.

Description

technical field [0001] The invention belongs to the technical field of image encryption, and in particular relates to a digital image compression encryption joint encoding method. Background technique [0002] In recent years, with the rapid development of multimedia and computer network technology, digital images, as the most intuitive information carrier, have become an important means for people to exchange information. It greatly facilitates the access and sharing of information; at the same time, there are huge security risks in the transmission of image information in many sensitive fields such as business, finance, medical care, scientific research, military affairs, and politics in an open network environment. Hidden dangers are often subject to various man-made attacks, including illegal theft, tampering and release of information, etc., causing huge losses to information owners. [0003] Compared with ordinary text information, digital images have the characterist...

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Problems solved by technology

[0006] Aiming at the shortcomings of the prior art, the present invention proposes a digital image compression encryption joint coding method to achieve the purpose of solving the problem that data cannot be effectively compressed after image encryption

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