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Multi-image encryption method based on log-polar transform

A technology of logarithmic polar coordinates and encryption method, which is applied in the field of information security, can solve problems such as reducing the quality of restored images and plaintext crosstalk, and achieves the effects of enhancing security, eliminating crosstalk, and increasing capacity

Inactive Publication Date: 2012-11-28
NANCHANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Although some multi-image encryption algorithms have been proposed one after another, many current algorithms encrypt multiple images into one image, and there is crosstalk between the restored plaintext, which greatly reduces the quality of the restored image.

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  • Multi-image encryption method based on log-polar transform
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  • Multi-image encryption method based on log-polar transform

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Embodiment Construction

[0058] The present invention will be further described below in conjunction with the embodiments and drawings, but the protection scope of the present invention should not be limited thereby.

[0059] Step 1: Select three digital images as the images to be encrypted, namely Lena, Peppers and Baboon, grayscale images with a level of 255, and a size of 512*512 pixels. figure 1 is the specific process of encryption, where , , represent three images to be encrypted respectively, RPM1 and RPM2 are two random phase templates whose values ​​are independently distributed in of white noise.

[0060] Step 2: Inversely transform the logarithmic polar coordinates of the three images respectively. In order to make the superimposed image after the transformation the same size as the original image, select an appropriate radius parameter. The maximum radius is selected as 255, and the size of the composite image is 511* 511. Let the first image radius parameter be selected as , th...

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Abstract

The invention discloses a multi-image encryption method based on log-polar transform. The method comprises the following steps of: with log-polar transform, encoding different images to different annular ranges, wherein the inner and outer radiuses of the different annular ranges are not overlapped; and superposing all annular images to obtain one image; and performing double-random phase encoding encryption on the superposed image on the basis of fractional Fourier transform in an optical mode, wherein the transform order of the fractional Fourier transform and the random phase template are used as keys and the inner diameter and outer diameter of the transform annular area can be used as secondary keys. The method disclosed by the invention is simple and easy to operate, improves the image encryption efficiency, and has relatively good attack resistance and relatively high safety.

Description

technical field [0001] The patent of the present invention belongs to the field of information security technology, in particular to image encryption technology. Background technique [0002] With the continuous development of global computer network and multimedia technology, people increasingly rely on the information resources of the Internet, so network information security cannot be ignored. As a special information carrier, image has become an important means of information expression due to its intuitive image characteristics. In some special fields, such as military, finance, telemedicine, etc., image data needs to be processed for confidential communication to prevent information theft, and image encryption has attracted more and more attention. However, images are different from text information. Images have a large amount of data, and the redundancy of information is relatively large, and some distortion of a decrypted image is acceptable as long as it does not a...

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Application Information

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IPC IPC(8): G06T1/00
Inventor 周南润刘兴斌龚黎华张文全
Owner NANCHANG UNIV