[vtkusers] existing filter to perform replace value on vtkImage

[Dominik Szczerba]

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Below some snippets how I use it.



calculator->SetResultArrayType(VTK_DOUBLE);

calculator->SetInput(viewer->image);

string function = "if("+scalarName+"=13,1,0)";
calculator->AddScalarArrayName(scalarName.c_str());
calculator->SetFunction(function.c_str());
calculator->SetResultArrayName(scalarName.c_str());



I operate on image data and filter out any pixels not falling into
explicit values. Modification for your purpose is straight forward.

Dominik

Michael Jackson wrote:
> On Feb 16, 2010, at 11:47 AM, David Doria wrote:
> 
>> On Tue, Feb 16, 2010 at 1:59 PM, Michael Jackson
>> <mike.jackson at bluequartz.net> wrote:
>>> Is there an existing filter where I can replace a value in the  
>>> image if the
>>> value does not meet some criteria? Something like:
>>>
>>> if (value < 255 ) value = 0;
>>>
>>> Thanks
>>> _________________________________________________________
>>> Mike Jackson                  mike.jackson at bluequartz.net
>> Two things come to mind -
>>
>> 1) You can identify those regions with vtkImageThreshold:
>> http://www.vtk.org/Wiki/VTK/Examples/Images/ImageThreshold
>> http://www.vtk.org/doc/nightly/html/classvtkImageThreshold.html
>>
>> 2) Maybe you can set all the pixels found in (1) to some specific
>> value, and then you can use
>> vtkImageMathematics::SetOperationToReplaceCByK to replace that
>> specific value with 0 (as your original question suggested you want to
>> do).
>>
>> Hope that helps,
>>
>> David
>>
> Thanks. I Took a look at those filters but did not really understand  
> what I was supposed to set any to? Basically I have a tiff file that  
> was supposed to be either black or white. Turns out there are also  
> intermediate values in there probably from some anti-aliasing or  
> something. So basically, if the value is NOT 255, replace it with 0. I  
> was thinking the Array Calculator but my simple mind couldn't really  
> come up with an equation that would give me what I want.
> 
> _________________________________________________________
> Mike Jackson                  mike.jackson at bluequartz.net
> BlueQuartz Software                    www.bluequartz.net
> Principal Software Engineer                  Dayton, Ohio
> 
> 
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