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Image wavelet de-noising method based on median filter

A wavelet denoising and image technology, applied in image enhancement, image data processing, instruments, etc., can solve the problems of easy loss of image edge information, frequency domain filter can not process images, image denoising effect is limited, etc., to reduce Calculation amount, moderate amount of calculation, stable effect of denoising effect

Inactive Publication Date: 2009-05-06
CHANGCHUN INST OF OPTICS FINE MECHANICS & PHYSICS CHINESE ACAD OF SCI
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Problems solved by technology

The spatial domain filter is easy to lose the edge information of the image, and the frequency domain filter cannot deal with the image where the noise and the signal spectrum are aliased, so the effect of image denoising using the above two types of algorithms is limited

Method used

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  • Image wavelet de-noising method based on median filter
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  • Image wavelet de-noising method based on median filter

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Embodiment Construction

[0021] like figure 1 As shown, the specific implementation device of the present invention includes image input, median pre-filtering, wavelet transform, threshold processing, wavelet inverse transform and image output module; the main method steps are:

[0022] (1) Perform median pre-filtering on the obtained noisy image;

[0023] (2) Calculate the orthogonal wavelet transform of the signal after median filtering to obtain the scale coefficients at low resolution L (0≤L<J) and the wavelet coefficients at each resolution, where J is the maximum decomposition scale;

[0024] (3) Perform threshold processing on wavelet coefficients, where λ is the threshold value of wavelet coefficients, that is, to compare the wavelet coefficients of noisy signals with threshold coefficients λ, and the points greater than 1.2λ are shrunk to the difference between the point and the threshold, and less than -1.2λ Shrink to the sum of the point value and the threshold

[0025] ...

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Abstract

The invention provides an image wavelet denoising method based on median filtering, which belongs to the field of digital remote sensing image processing. In the method, median pre-filtering is firstly performed on images containing noise, wavelet conversion, threshold value treatment and denoising treatment are then carried out, wavelet reverse conversion is finally carried out, and filtered images are output. The invention has the advantages that the median filtering method is used for the pre-filtering of images containing noise, much noise of pepper salt type is removed, and influence on the high-frequency part of images is avoided; the wavelet threshold value method is then combined with the denoising method of the relativity of wavelet coefficient size, and the mixture of signal coefficient and noise coefficient caused by using the wavelet threshold value method singly is avoided; and meanwhile, a large amount of computation required by using the denoising method of the relativity of wavelet coefficient size singly is reduced. The experiments prove that the method has stable denoising effect and moderate computation amount.

Description

Technical field: [0001] The invention belongs to the field of digital remote sensing image processing, and proposes an image wavelet denoising method based on median filtering. Background technique: [0002] The shooting environment of remote sensing images is often relatively harsh, and the main influences are: the design and assembly of optical lenses, the control of defocus, the control of exposure, the compensation of phase shift, the performance of detectors, and the signal-to-noise ratio of image transmission channels etc. The image thus obtained is a collection of the real image and the noise caused by the above unfavorable factors. In order to restore the original image more accurately and reduce image misjudgment and missed judgment caused by noise in the process of image interpretation, it is necessary to denoise the obtained image. [0003] Traditional image denoising algorithms are mainly analyzed and designed separately from two aspects of frequency domain and...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T5/00
Inventor 匡海鹏王德江周刚
Owner CHANGCHUN INST OF OPTICS FINE MECHANICS & PHYSICS CHINESE ACAD OF SCI
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