multiplicative noise generate using randn

vipul utsav (view profile)

on 17 Mar 2013
Latest activity Commented on by Image Analyst

on 18 May 2018

Image Analyst (view profile)

n=0+(sd)*randn(size(original image)) and i apply noise estimation algorithm to noisy image and i found additive noise.
If i needs to simulate noise estimation algorithm using multiplicative noise,how i generate noisy image with multiplicative noise? (only using 'randn' function, not using imnoise)

Image Analyst (view profile)

on 17 Mar 2013
Edited by Image Analyst

Image Analyst (view profile)

on 17 Mar 2013

noiseOnlyImage = sd * randn(size(noiseFreeImage));
noisyImage = noiseFreeImage .* noiseOnlyImage;
% Cast to uint8 if you want.
imshow(noisyImage, []); % Use [] if it's a double image.

Image Analyst

Image Analyst (view profile)

on 20 Mar 2013
The probability density function for laser speckle is
pdf = exp(-v/sigmaSquared) / sigmaSquared
from section 5.9 in book by Roy Frieden "Probability, Statistical Optics, and Data Testing". v is the intensity of the light. So you can see it's an exponential decay, not a Guassian because it depends on v not v^2.
Saija Bhumireddy

Saija Bhumireddy (view profile)

on 18 May 2018
what does sd mean? I see that it is not an inbuilt function. can someone explain this plss
Image Analyst

Image Analyst (view profile)

on 18 May 2018
sd is a variable that represents the standard deviation. It's something you assign a desired value to.