adding noise to images

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)

Answer 1

[David Hill]

black=find(image==0);
white=randperm(length(black),floor(x/100*length(black)));
image(white)=uint8(255);

[Kamyar Mazarei]

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]

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.