Write a function to add random noise to an image in matlab

Question

Krish Desai 2015-10-9

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https://ww2.mathworks.cn/matlabcentral/answers/247765-write-a-function-to-add-random-noise-to-an-image-in-matlab

评论： Image Analyst 2019-9-18

How do I create a function to add random noise without using imnoise? I am trying to figure out how to do it without using the built-in matlab functions. I know I have to add a random integer to every pixel...

function output=randomnoise(current_img)
for current_img(n)
    current_img(n)=current_img(n)+ randi([-255 255],1)
    n=n+1
end

This is what I am coming up with right now, but I don't think my loop is visiting each value. How do I visit each pixel and how do I add random noise to it?

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Walter Roberson 2015-10-9

The distribution of random value you add to the pixel is important.

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Answer 1

Image Analyst 2015-10-10

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https://ww2.mathworks.cn/matlabcentral/answers/247765-write-a-function-to-add-random-noise-to-an-image-in-matlab#answer_195403

在 MATLAB Online 中打开

Try this:

function output=randomnoise(current_img)
% Cast to double;
current_img = double(current_img);
[rows, columns] = size(current_img)
for col = 1 : columns
    for row = 1 : rows
        output(row, col) = current_img(row, col)+ randi([-255 255],1)
    end
end

Or you could do away the the two loops and just vectorize it

noise = randi([-255, 255], rows, columns);
output = current_img + noise;

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Answer 2

Walter Roberson 2015-10-9

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http://www.mathworks.com/help/matlab/ref/for.html

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Answer 3

Arifaa A 2019-9-18

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https://ww2.mathworks.cn/matlabcentral/answers/247765-write-a-function-to-add-random-noise-to-an-image-in-matlab#answer_392425

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function output=randomnoise(current_img)
% Cast to double;
current_img = double(current_img);
[rows, columns] = size(current_img)
for col = 1 : columns
    for row = 1 : rows
        output(row, col) = current_img(row, col)+ randi([-255 255],1)
    end
end
noise = randi([-255, 255], rows, columns);
output = current_img + noise;