[Insight-users] add noise

[cecilia.zanella at studio.unibo.it]

Hi Luis,
I would like to follow the second option. So, I have to use the 
itkRandomImageSource filter and pass the values of the resulting pixels to 
an inverse erf() function, finally I have sum the two resulting images. I 
have to ask you another question: how can I generate the inverse erf() 
function?
Thank you,
Cecilia


----- Original Message ----- 
From: "Luis Ibanez" <luis.ibanez at kitware.com>
To: <cecilia.zanella at studio.unibo.it>
Cc: <Insight-users at itk.org>
Sent: Friday, May 12, 2006 3:14 PM
Subject: Re: [Insight-users] add noise


>
> Hi Cecilia,
>
> There is no currently a filter in ITK for adding Gaussian noise.
>
> However you can easily put one together by combining the
> following classes:
>
> 1) Insight/Code/BasicFilters/itkRandomImageSource.h
>    Insight/Code/BasicFilters/itkRandomImageSource.txx
>
> 2) Insight/Code/Numerics/Statistics/itkNormalVariateGenerator.h
>    Insight/Code/Numerics/Statistics/itkNormalVariateGenerator.cxx
>
>
> The RandomImageSource is designed to generate an image with noise
> following a Uniform distribution. You can replace the computation
> of the uniform distribution by going to lines: 153-155 of the
> itkRandomImageSource.txx and in there make calls to the Normal
> VariateGenerator.
>
>
> As a second option, you could simply take the values currently
> generated from the uniform distribution, and pass them as argument
> to an inverse erf() function, the values that are produced as output
> will follow a Gaussian distribution.
>
>
> You probably want to rename the resulting filter as a
> GaussianNoiseSource, or something along those lines.
>
> Once you get this filter working, you could simply use the AddImage
> filter in order to combine your input image with the Gaussian noise
> image that you obtain from this filter.
>
>
> Do you need the random image to be reproducible ?
> or do you want it to be different every time that you run the filter ?
>
>
> Please let us know if you find any problems,
>
>
>    Thanks
>
>
>      Luis
>
>
>
> =========================================
> cecilia.zanella at studio.unibo.it wrote:
>> Hi,
>> I have to add (Gaussian) noise to a synthetic volume: is there an ITK 
>> filter able to execute this task?
>> Thank you all...
>>
>> Cecilia
>>
>>
>> _______________________________________________
>> Insight-users mailing list
>> Insight-users at itk.org
>> http://www.itk.org/mailman/listinfo/insight-users
>>
>>
>
>
>