Image is Noisy or not ?

Hey Everyone ! I'm working on a project which includes to examine either the provided/selected image is noisy or not ?Is the given image is aesthetically acceptable or not.what should be the steps to follow to judge that ?

Any helpful response will be highly appreciated . Thanks in advance

Answer 1

[Changoleon]

Hi. this question is very qualitative. What kind of noise does your images has?

Let's assume your image has "salt & pepper" noise ( please see the attached image - the attached picture has salt and pepper noise and also some other sources of noise)

In order to judge if an image has salt and pepper noise, you could count the number of pixels in that image which have the intensity values of 0 and 255. And if the numbers is higher than a specific threshold then you could say that your image has salt and pepper noise or not. For instance

a = double(imread('actin_noise.bmp'));      %( download the attached image )

b = sum(sum(a==255));    %this counts the number of white pixels (salt noise)

c = sum(sum(a==0));      %this counts the number of black pixels (pepper noise)

threshold = 2000;       % this number needs to be determined by you

if b||c > threshold

      fprintf ('Your image has Salt & Pepper noise /d')

end

[Tahira Batool]

But Sir I can not view the attached image.its just a small white square box.

[Changoleon]

Once you click on it, the white page will appear. Then you can right click and click on save as to download the image

Answer 2

[Image Analyst]

I suggest you start with these links:

https://en.wikipedia.org/wiki/Image_quality

https://en.wikipedia.org/wiki/Video_quality

https://en.wikipedia.org/wiki/Subjective_video_quality

http://www.mathworks.com/matlabcentral/fileexchange/41464-image-quality-index-analysis-gui

[Tahira Batool]

The very first link you have provided is about image quality contains a section named " Image quality factors" in which Noise is also mentioned with other factors which is the pixel level variation in captured image .How one can measure it ? what techniques to follow for this purose ?

[Image Analyst]

You can read this paper for a comprehensive overview of noise and filtering methods: https://users.soe.ucsc.edu/~milanfar/publications/journal/ModernTour.pdf

The Image Processing Toolbox also has functions std2(), immse(), and psnr().