adding noise to images

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Kamyar Mazarei
Kamyar Mazarei on 15 Apr 2021
Edited: David Hill on 15 Apr 2021
hi
i need to add x% noise ONLY to black areas of my image (image is grayscale) so x% of the black areas be replaced with white (changing 0 to 255)

Answers (1)

David Hill
David Hill on 15 Apr 2021
Edited: David Hill on 15 Apr 2021
black=find(image==0);
white=randperm(length(black),floor(x/100*length(black)));
image(white)=uint8(255);
  2 Comments
Kamyar Mazarei
Kamyar Mazarei on 15 Apr 2021
Edited: Kamyar Mazarei on 15 Apr 2021
thanks for the reply
but it works only to a small part of the image
like if i make x=100 it will remove only a small part of the image
the nosie isnt being added to the whole image
can you hlep please
thank you
David Hill
David Hill on 15 Apr 2021
Edited: David Hill on 15 Apr 2021
You could put in a range. My guess is that you think it is black but is not (==0).
black=find(image<10);%change range until you are satisfied.

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