What is the mathematics behind the imnoise function in matlab?

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Ashwani 2013-1-2

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Actually I want to know that how imnoise add noise to a signal .which method it follows.

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Answer 1

Walter Roberson 2013-1-2

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It depends which kind of noise. http://www.mathworks.com/help/images/ref/imnoise.html

Most of the supported types are essentially randn() * scale + mean

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Ashwani 2013-1-2

Thanks for reply. If I am using J = imnoise(I,'gaussian',m,v),( m = 0,v=1). Then how it add noise to 'I'.

Jurgen 2013-1-2

I would guess newpixel = originalpixel + randn(1). For every pixel in image, in other words J = I + randn(size(I)). See 'help randn' on how to get different means/variance.

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Answer 2

Image Analyst 2013-1-2

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This is all spelled out in the help for the different types of noise you can choose from. It assumes the image is normalized 0-1 and then adds the noise you selected, then it unnormalizes the image to get back to the original intensity range. Was there one particular type of noise that you did not understand the definition of?