[vtkusers] Combination of two images

[David Gobbi]

Hi Adrien,

The alpha mask should have values of 0 and 255:
opac.ReplaceInOn();
opac.ReplaceOutOn();
opac.SetInValue(255);
opac.SetOutValue(0);

 - David


On Wed, Apr 13, 2011 at 7:33 AM, Adrien Marion
<adrien.marion at creatis.insa-lyon.fr> wrote:
> Thank you David.
> vtkImageStencil is not OK adding
>
> IS.SetInput(img);
>
> So I tried your second solution doing (test with python):
>
> opac = vtkImageThreshold();
> opac.SetInput(img);
> opac.ThresholdByUpper(1);
> opac.SetInValue(1);
> opac.Update();    // Thresholded image with 2 levels (0 and 1)
>
> app = vtkImageAppend();
> app.SetInput(img);
> app.SetInput(opac.GetOutput());
> app.Update();    // Image with 2 components, the initial one (img) and the
> associated binary mask
>
> blend = vtkImageBlend();
> blend.SetInput(app.GetOutput());
> blend.SetInput(currentImage);
> blend.Update();
>
> However, It does not provide the good combination. Did I wrote mistakes ?
> I do not understand how to say that the blend must take the second component
> of app (i.e. the binary mask) to decide if pixels have to be replaced.
>
> Adrien
>
> Le 13/04/2011 14:59, David Gobbi a écrit :
>>
>> Hi Pat,
>>
>> The vtkImageStencil filter can take two image inputs, try adding this:
>>
>>
>>
>> You can also combine the images without using stencils.  To do this,
>> you would use vtkImageThreshold to generate your mask image, and then
>> vtkImageAppend to append this mask to img as an alpha channel.  Then
>> vtkImageBlend can be used to combine the images, it will use the alpha
>> channel to decide which pixels to replace.  This method doesn't have
>> any advantage compared to using stencils, it's just a different way of
>> doing the same thing.
>>
>>  - David
>>
>> On Wed, Apr 13, 2011 at 6:42 AM, Adrien Marion
>> <adrien.marion at creatis.insa-lyon.fr>  wrote:
>>>
>>> Hi,
>>> I have two vtkImageData (called currentImage and img), each containing
>>> values from 0 to 250.
>>> I would like to combine these images to obtain a resulting image
>>> (resImage)
>>> doing for each pixel:
>>> - if Mask == 0, resImage = currentImage
>>> - else resImage = Mask
>>>
>>> I currently work with VTK wrapped version in Java and I cannot afford a
>>> triple loop with getScalarAsDoubleComponent to do that.
>>>
>>> Does someone have a simple solution to do that ?
>>>
>>> I already tried with vtkImageStencil but It does not give the good
>>> solution:
>>>
>>>        vtkImageToImageStencil IIS = new vtkImageToImageStencil();
>>>        IIS.SetInput(img);
>>>        vtkImageStencil IS = new vtkImageStencil();
>>>        IS.SetStencil(IIS.GetOutput());
>>>        IS.SetInput(currentImage);
>>>        IS.Update();
>>>        result = IS.GetOutput();
>>>
>>> I think I did not understand how vtkImageStencil works.
>>>
>>> Thank you in advance for your help,
>>> Adrien
>>>
>>> --
>>> Adrien MARION, Docteur/PhD
>>> Chercheur post-doctorant (ANR VIP)
>>> Laboratoire CREATIS, INSA de Lyon
>>> CNRS UMR 5220, INSERM U1044
>>> Bâtiment Blaise Pascal, 4ème étage
>>> 7, avenue Jean Capelle
>>> 69621 Villeurbanne cedex FRANCE
>>> Tel : (+33) 4 72 43 87 86
>>> Fax:  (+33) 4 72 43 85 26
>>> e-mail : adrien.marion at creatis.insa-lyon.fr
>>> http://www.creatis.insa-lyon.fr/~amarion
>
> --
> Adrien MARION, Docteur/PhD
> Chercheur post-doctorant (ANR VIP)
> Laboratoire CREATIS, INSA de Lyon
> CNRS UMR 5220, INSERM U1044
> Bâtiment Blaise Pascal, 4ème étage
> 7, avenue Jean Capelle
> 69621 Villeurbanne cedex FRANCE
> Tel : (+33) 4 72 43 87 86
> Fax:  (+33) 4 72 43 85 26
> e-mail : adrien.marion at creatis.insa-lyon.fr
> http://www.creatis.insa-lyon.fr/~amarion