Image camouflage and reconstruction method based on tangram algorithm and 2D dual-scale rectangular mapping

Abstract

The invention provides an image disguising and reconstructing method based on a Tangram algorithm and two-dimensional double-scale rectangular mapping. Subblocks obtained by dividing a secret image serve as a dictionary, the corresponding relation between the secret image subblocks and public image subblocks is determined through two-dimensional double-scale rectangular mapping, least square method matching is directly carried out on each secret image subblock and the public image subblock at the corresponding position according to eight isometric transformation, the isometric transformation and matching parameter with the minimum residual error is found out, and therefore the secret image is disguised to be a meaningful public image not related to the secret image to be transmitted in a public channel. Matching is carried out only according to the mapping relation, the actual encoding time is far shorter than that of an existing Tangram method, the public image can meet a certain identification requirement, vision quality of the reconstructed secret image is good, and as the two-dimensional double-scale rectangular mapping is added, the mapping position is disturbed randomly, and a certain safety requirement can be met.

Description

technical field [0001] The invention belongs to the intersecting research fields of information security and digital image signal processing, and relates to a digital image camouflage method, in particular to an image camouflage and reconstruction method based on Tangram algorithm and 2-dimensional double-scale rectangular mapping. Background technique [0002] In recent years, with the development of computer and network technology, more and more digital images are spread in public channels. Unrestricted access to and use of secret images not only involves personal privacy, media credibility, and government integrity, but can also lead to social unrest and induce military conflicts. [0003] How to effectively protect secret images transmitted in public channels has become a hot research topic at present. Aiming at this problem, people have proposed a variety of image protection methods, such as digital image encryption technology that converts plaintext images into cipher...

AI Technical Summary

Problems solved by technology

[0037] However, converting small image blocks into 5-tuples for matching reduces the matching accuracy, thereby further reducing the secret image reconstruction accuracy

At the same time, since the threshold δ cannot be estimated in advance, if the value of δ is small, it is equivalent to global search; if the value of δ is large, the reconstruction accuracy of the secret image will be further reduced; at the same time, the computational cost of using the threshold δ to reduce is still very limited

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