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Noise Level Estimation from a Single Image

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Noise Level Estimation from a Single Image

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30 May 2012 (Updated )

It can precisely estimate noise level from a single image.

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This file was selected as MATLAB Central Pick of the Week

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File Information
Description

 NoiseLevel estimates noise level of input single noisy image.
 [nlevel th num] = NoiseLevel(img,patchsize,decim,conf,itr)
Output parameters
 nlevel: estimated noise levels.
 th: threshold to extract weak texture patches at the last iteration.
 num: number of extracted weak texture patches at the last iteration.
 
 The dimension output parameters is same to channels of the input image.

Input parameters
 img: input single image
 patchsize (optional): patch size (default: 7)
 decim (optional): decimation factor. If you put large number, the calculation will be accelerated. (default: 0)
 conf (optional): confidence interval to determin the threshold for the weak texture. In this algorithm, this value is usually set the value very close to one. (default: 0.99)
 itr (optional): number of iteration. (default: 3)

Example:
 img = double(imread('img.png'));
 nlevel = NoiseLevel(img);

Web page:
 http://bit.ly/NLest (http://www.ok.ctrl.titech.ac.jp/res/NLE/noise_level.html)

Reference:
 Xinhao Liu, Masayuki Tanaka and Masatoshi Okutomi
 Noise Level Estimation Using Weak Textured Patches of a Single Noisy Image
 IEEE International Conference on Image Processing (ICIP), 2012.

Xinhao Liu, Masayuki Tanaka and Masatoshi Okutomi,
Single-image Noise Level Estimation for Blind Denoising,
IEEE Transactions on Image Processing, Vol.22, No.12, pp.5226-5237, 2013.

Acknowledgements

This file inspired Noise Level Estimation, Fast Noise Estimation In Images, and Signal Dependent Noise Level Estimation.

Required Products Image Processing Toolbox
MATLAB release MATLAB 7.14 (R2012a)
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Comments and Ratings (13)
19 Jun 2014 Qiaohong Li  
23 Mar 2014 Masayuki Tanaka

Hi Akshay Gore,

You can download the dataset from:
https://www.eecs.berkeley.edu/Research/Projects/CS/vision/bsds/

Thanks!

17 Mar 2014 Akshay Gore

How to test model on Berkeley Segmentation Dataset?
Akshay Gore
akshaygore@live.com

15 Mar 2014 Masayuki Tanaka

Hi Ashish,

I don't use the exact block toeplitz for two-dimensional image. As I commented, I used the different matrix.
my_convmtx2 generates the matrix associated to the following code:

imgh = imfilter(img,kh,'replicate');
imgh = imgh(:,2:size(imgh,2)-1,:);

Thanks.

14 Mar 2014 Ashish Meshram (Meet)

Hi Masayuki

Yeah I saw that code but I've tried to get it done by toeplitz matrix only for Directional Derivative operator to calculate threshold and results are coming satisfactorily but takes time longer as compared to yours code.

Once it seems to be final I'll be uploading it.

Thanks for your reply....

13 Mar 2014 Masayuki Tanaka

Hi Ashish Meshram,

You can find the source code of my_convmtx2 in the file of NoiseLevel.m.
Please check it out!

Thanks.

13 Mar 2014 Masayuki Tanaka

Hi Ashish Meshram,

In the matlab code, I did not use the toeplitz matrix to calculate the
derivatives. I simply use the imfilter function instead of the matrix.
The matrix associated to the derivative operation in the matlab code is
not square matrix. The reason is to handle the borders of each patch
correctly.

Thanks.

09 Mar 2014 Ashish Meshram (Meet)

AS mentioned in your paper at section III, equation no. 7, where by Dh and Dv are toeplitz matrix of N^2XN^2 but that not the case. For default patch size of 7 it should return 49X49 its return 35X49.

What the reason for this...

Thanks

08 Mar 2014 Ashish Meshram (Meet)

Hello Masayuki Tanaka

Could you please mention some details about the function

T = my_convmtx2(H, m, n)

And if not possible here in, please refer me to some pointer

Thanks

01 Mar 2014 Ashish Meshram (Meet)

Great job

27 Feb 2014 Masayuki Tanaka

Hi Samuele Fiorini,

Thank you for your comment.
What kind of image and how much noise did you try?

Thanks.

14 Feb 2014 Samuele Fiorini

It fails in case of very low noise, I cannot figure out why. Any help?

14 Jun 2012 jackal tao

good

Updates
30 May 2012

Added help.

01 Jun 2012

Added the web information.

06 Jun 2012

Debugged for zero-iteration case.

13 Jun 2012

Debugged threshold calculation and change default parameter.

03 Mar 2014

Add new reference to description.

07 May 2014

Bug fixed.

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