# Image is Noisy or not ?

3 views (last 30 days)
Tahira Batool on 17 Nov 2016
Edited: Changoleon on 17 Nov 2016
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 ?

Changoleon on 17 Nov 2016
Edited: Walter Roberson on 17 Nov 2016
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
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 on 17 Nov 2016
But Sir I can not view the attached image.its just a small white square box.
Changoleon on 17 Nov 2016
Edited: Changoleon on 17 Nov 2016
Once you click on it, the white page will appear. Then you can right click and click on save as to download the image

Image Analyst on 17 Nov 2016
Tahira Batool on 17 Nov 2016
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 on 17 Nov 2016
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().

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