‎"Behind every stack of books there is a flood of knowledge."



This demonstration is a comparison of two methods to denoise an image:

  • the Wiener filter
  • a denoising using smooth operators:

Denoising with the Wiener filter

This is the classical way to reduce the additive noise in an image, it is also called a minimum mean-square estimator. The denoising is performed in the spatial domain using the following transfert function:

Wiener Filter Diagram


  • F(u,v) : is the Fourier transform of the original image (uncorrupted image) with mf as mean
  • N(u,v) : is the Fourier transform of the additive noise with mn as mean

In practical implementations, the noise |N(u,v)|2 is not available, so it is replaced by a constant K. If the noise is white with a variance of s2 and the mean is zero, a good estimation of K is K = s2.

Denoising using a smoothing operator

An alternative to the Wiener filter is an algorithm using smoothing operators to denoise an image. The implementation corresponds to the following diagram:

Wiener Filter Diagram

The smoothing operator is the well-known “Gaussian filter” with s that controls the strength of the smoothing. The threshold opertor is a “Soft thresholding” with a threshold parameter t that controls which low values are suppressed.

The method doesn’t require the knowledge of the noise or its estimation and it is possible to set the denoising with two parameters: s and t.

Example on Lena image
Cells Original Border
Input Image 

Lena image with additive noise (20).

Cells Original Border
Output Image with the Wiener filter

SNR = 18.55

Cells Original Border
Output image with the denoising using smooth operator 

Sigma = 1.5

Threshold = 34

SNR= 21.61




Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Virtual Fashion Technology

Virtual Fashion Education


"chúng tôi chỉ là tôi tớ của anh em, vì Đức Kitô" (2Cr 4,5b)


News About Tech, Money and Innovation


Modern art using the GPU

Theme Showcase

Find the perfect theme for your blog.


Learn to Learn

Gocomay's Blog

Con tằm đến thác vẫn còn vương tơ

Toán cho Vật lý

Khoa Vật lý, Đại học Sư phạm Tp.HCM - ĐT :(08)-38352020 - 109

Maths 4 Physics & more...

Blog Toán Cao Cấp (M4Ps)

Bucket List Publications

Indulge- Travel, Adventure, & New Experiences


‎"Behind every stack of books there is a flood of knowledge."

The Blog

The latest news on and the WordPress community.

%d bloggers like this: