Image compression secure coding method based on multidirectional sparse representation

A sparse representation and image compression technology, applied in image communication, television, electrical components, etc., can solve the problems of lack of translation invariance, difficulty in efficient representation of singular features, statistical damage of image pixels, etc., to improve directional flexibility and sparseness. performance, good objective quality and subjective effect, good nonlinear approximation performance

Inactive Publication Date: 2010-09-29
SOUTHWEST JIAOTONG UNIV
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Problems solved by technology

However, DWT has two major drawbacks: (1) lack of translation invariance, that is, a small translation of the input signal can lead to large changes in DWT coefficients; (2) lack of direction selectivity, that is, for non-horizontal or non-vertical singular Features are difficult to express efficiently
However, this transformation needs to find the optimal decomposition structure, so the computational complexity is relatively high
[0004] According to the image compression process, image encryption is divided into three categories: (1) Encrypt the image before compre

Method used

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  • Image compression secure coding method based on multidirectional sparse representation
  • Image compression secure coding method based on multidirectional sparse representation
  • Image compression secure coding method based on multidirectional sparse representation

Examples

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Embodiment 1

[0029] A specific embodiment of the present invention is a method for image compression secure encoding based on multi-directional sparse representation, the steps of which are as follows:

[0030] a. Multi-directional dual-tree discrete wavelet transform: Firstly, the image is decomposed by dual-tree discrete wavelet transform. When decomposing, the first layer is decomposed by CDF 9 / 7 filter bank, and the remaining layers are decomposed by 6-tap q-shift The filter bank is decomposed to obtain high-frequency subbands in six directions of -75°, -45°, -15°, 15°, 45° and 75°; then use each direction for the obtained high-frequency subbands in six directions The anisotropic directional filter bank is decomposed, and the anisotropic directional filter bank is constructed by the 7th-order maximum flat diamond filter through McClellan transformation and modulation, and the support lengths of the high-pass and low-pass filters are (29, 29) and (43, 43); after decomposing, the decompo...

Embodiment 2

[0048] The operation of this example is basically the same as that of Example 1, except that in the operation of step a, when decomposing the obtained high-frequency sub-bands in six directions with an anisotropic directional filter bank, anisotropic transform. Correspondingly, the strategy during the c-step interleaving is changed to: interleave each row or each column for the coefficients obtained in the b-step.

[0049] The simulation experiment of this example method is as follows

[0050] The original image selected in this experiment is a texture-rich palmprint, and its size is a grayscale image of 512×512. Anisotropic transformation is used for directional filter decomposition, and the number of hierarchical decompositions at each level is [0 0 0 3 3 3].

[0051] The images obtained in this experiment are Figure 6 to Figure 9 ,in: Figure 6 is the original image; Figure 7 for right Figure 6 The simulated compressed (decoded) image obtained when the compression ...

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Abstract

The invention discloses an image compression secure coding method based on multidirectional sparse representation, comprising the following steps of: performing discrete dual-tree wavelet transform on an image and then performing directional filtering on each obtained high-frequency sub-band to obtain fine image directional sparse representation; performing rarefaction process on an obtained directional sub-band coefficient by using a noise shaping technology; interleaving the coefficients of each layer to ensure that the sub-band coefficients of neighbor layers have a parent child relation, and then performing quantitative coding on the coefficients by using SPIHT (Set Partitioning in Hierarchical Trees); and finally encrypting the coefficient symbols in a code stream in an XOR (Exclusive OR) manner and encrypting other partial code streams by using random arithmetic coding. As the code stream obtained by coding is encrypted by using the random arithmetic coding, the encryption efficiency is high, the effect is good, the security is high and no influence is brought to the image compression performance. The high-frequency components of the image are decomposed by using a directional filter, and therefore the directional representation is more flexible, sparser image representation is obtained, the image coding compression process is favored and the decoded image has better objective quality and subjective effect.

Description

technical field [0001] The invention relates to a secure encoding method based on image compression, in particular to an image compression secure encoding method based on multi-directional sparse representation of random arithmetic coding. Background technique [0002] With the rapid development of multimedia such as networks and images, multimedia communication such as images has gradually become an important means of information exchange between people. The current network is an open system, so before transmitting important images, images need to be encrypted to ensure security. The traditional encryption technology encrypts it as an ordinary data stream without considering the characteristics of multimedia data, so it has certain limitations. For example, the data volume of an image is generally relatively large, and the amount of calculation required for encryption is relatively large, resulting in the problem of low encryption efficiency. In addition, the data size of...

Claims

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Application Information

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IPC IPC(8): H04N7/26H04N7/30H04N19/63
Inventor 张家树李恒建
Owner SOUTHWEST JIAOTONG UNIV
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